This Month's Star

This month look for the star Alcyone, the brightest star in the open cluster, the Pleiades. To the Japanese, the cluster is known as Subaru. If you look at the emblem on the same car you’ll see the Pleiades. The Pleiades goes by the name of M-45 and is also known as the Seven Sisters. Most people only see six stars in the Pleiades. The seven sisters were daughters of the titan, Atlas and his wife, Pleione. The six stars most people see, in order of brightness, are named, Alcyone, Electra, Maia, Atlas, Merope, and Taygeta. The next three fainter stars are named after the their mother and the two remaining sisters, Pleione, Celaeno, and Asterope   The first known mention of the Pleiades is by the writer Hesiod around 1000 BC.  

In 10X50 binoculars, the brightest portion of the Pleiades occupies about 1/5th of the field of view. When you include the fainter surrounding stars, the Pleiades occupies closer to 1/4th of the field of view. In moderately light polluted skies, I could easily see 20 stars. In the diagram above, Alcyone, the brightest Pleiad, is the star in the center.

The Pleiades are 369 light years away. So the light you see tonight left the star cluster in the year 1645. There are some 500 stars in this galactic cluster. They formed from the same cloud of dust and gas about 100 million years ago. This means they were born during the middle of the Cretaceous period, or during the hey-day of the dinosaurs. In time the stars of this cluster will drift a part, as their gravity is too weak to hold the cluster together. In other words, there are too few stars spread too far a part. In long duration exposures a blue cloud of dust can be seen surrounding the stars. The stars and bright blue-white frosting makes the Pleiades look like some fantastic piece of jewelry. Contrary to popular belief, this is not the remains of the cloud that the Pleiades formed from. It happens to be a separate cloud that the cluster is currently drifting through. Recent findings have determined that the cloud of dust is actually two separate clouds that are passing each other just as the Pleiades are passing through the same area.  

Transcript for 29 December to 4 January

PAUL
Welcome to Idaho Skies for the first week of January. We’re your hosts, Paul…

RACHEL
… and Rachel.

PAUL
We have two birthdays, an anniversary, and a meteor shower this week.

RACHEL
January 2nd is the birthday of writer Isaac Asimov.

PAUL
Asimov passed away in 1992, but he would have been 94 this year.

RACHEL
Most of our listeners know Asimov for his science and science fiction books.

PAUL
However, he also wrote on many other topics like history and literature.

RACHEL
Did you know he published over 500 books in his lifetime?

PAUL
It helps when you publish your first book at age 19.

RACHEL
The 2nd also marks ten years since the Stardust mission flew past comet Wild 2.

PAUL
Stardust collected samples of comet’s dust as it flew by at a distance of 126 miles.

RACHEL
Then two years later, its reentry capsule returned to Earth in Utah, bringing those samples back for analysis.

PAUL
Although we spell the comet’s name like the word wild, it’s actually the name of the German astronomer who discovered it.

RACHEL
The two comes from the fact that this was his second comet discovery.

PAUL
In the world of professional astronomy, the discoverer of a new comet has the privilege of naming the comet after him or her.

RACHEL
The first astronomer to have this honor was Edmund Halley.

PAUL
Halley didn’t actually discover this comet; people had observed it for over 1,000 years.

RACHEL
One example is the Bayeux Tapestry, where the comet’s image adds a sense of foreboding for the king of England, Harold.

PAUL
We name the comet after Halley because he was the first to determine that many of the comet’s observed over history were actually the same comet returning every 76 years.

RACHEL
He also predicted when it would make its next appearance.

PAUL
Edmund Halley never lived to see his predicted comet return, however, since he nailed its return, we name the comet after him.

RACHEL
Halley predicted the return of his comet because he was a friend and firm believer in Isaac Newton.

PAUL
Newton also celebrates this birthday this week.

RACHEL
On the 4th as a matter of fact.

PAUL
Our astronomical event for this week is the Quadrantid meteor shower.

RACHEL
It’s a nice shower that peaks on the night of the 3rd and morning of the 4th.

PAUL
Quadrantid meteors will appear to radiate from low in the northeast, at a point just below the bowl of the Big Dipper.

RACHEL
The shower is best observed after midnight.

PAUL
You can expect to see 45 meteors per hour from this shower.

RACHEL
However, most of them won’t be bright, so watch from a dark location.

PAUL
The best way to watch this shower is to lie back on a lawn chair and look straight up.

RACHEL
Be sure to take a warm sleeping bag with you.

PAUL
And hot drinks are also helpful.

RACHEL
That’s Idaho Skies for the first week of January. Next week Earth reaches perihelion and we celebrate the discovery of Jupiter’s satellites.

PAUL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for December 22 - 28

RACHEL
Welcome to Idaho Skies for the last week of December. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
December’s second meteor shower peaks on the 22nd.

PAUL
Meteors from the Ursid meteor shower appear to originate from the north and are at their best before the moon rises at 10:00 PM.

RACHEL
You can expect to see about a dozen faint meteors per hour from this shower.

PAUL
However, it has surprised astronomers with significantly higher rates on occasion.

RACHEL
When the moon rises on the morning of the 25th, look for a slightly orangish star to its left.

PAUL
That’s Mars.

RACHEL
Unfortunately, this is not a good time to view Mars through a telescope as it’s too far away and too small in diameter to show any detail.

PAUL
Every two years this changes however, so be patient.

RACHEL
The moon is last quarter on the 25th.

PAUL
So if you got a new telescope for Christmas, you can test it on the moon.

RACHEL
That is if you can wait until it rises after 2:00 AM on the 26th.

PAUL
Want to try out your new telescope on Saturn?

RACHEL
You can easily find Saturn on the morning of the 28th if you find the crescent moon first.

PAUL
It’s located in the low east.

RACHEL
At 6:00 AM, Saturn is the creamy-yellow star to the moon’s lower left.

PAUL
You will need a magnification of at least 25 times to see its rings.

RACHEL
But less magnification is required to see its largest satellite, Titan.

PAUL
Titan will appear star-like in your telescope

RACHEL
And it’s to Saturn’s upper right.

PAUL
Much closer to the moon is a star named Zubenelgenubi.

RACHEL
This star is a wide double star and it’s easy to split into two stars through binoculars.

PAUL
A thin crescent moon, just two days from new, appears in the morning sky on the 30th.

RACHEL
To see it, use binoculars and begin sweeping the low southeast at 6:45 AM.

PAUL
The moon will be less than a binocular’s field of view above the horizon.

RACHEL
But you’ll need to work quickly though.

PAUL
That’s because by 7:15 AM, the sky will begin brightening enough to make it difficult to see the moon.

RACHEL
Looking any later is dangerous too because you might sweep up the sun in your binoculars.

FADE IN MUSIC

PAUL
That’s Idaho Skies for the last week of December. Join us next month for the space and astronomy events for Idaho.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com For Idaho Skies this is Rachel...

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Meteor Presentation

The Street Astronomer gave a presentation on meteors last week at Deer Flat NWR. The presentation is now online at SlideShare.

http://www.slideshare.net/NearSys/meteor-showers-29232037

Transcript for December 15 to 21

PAUL
Welcome to Idaho Skies for the third week of December. We’re your hosts, Paul...

RACHEL
...and Rachel.

PAUL
On the evening of the 15th, the moon is next to the Hyades star cluster.

RACHEL
The Hyades is the large star cluster that forms the face of Taurus the Bull.

PAUL
Because of the size of the Hyades, this is an event for your binoculars and not a telescope.

RACHEL
The moon is full on the night of the 17th.

PAUL
Also, there are two important historical events on the 17th that helped create today’s space and astronomy world.

RACHEL
We begin with the first heavier than air flight.

PAUL
One hundred and ten years ago, Orville and Wilbur Wright flew their airplane, the Wright Flyer for 12 seconds.

RACHEL
The flight took place at a sand dune named Big Kill Devil Hill and the airplane only flew 120 feet.

PAUL
Even though the flight was shorter than the wing span of a Boeing 747, it ushered in the age of flight.

RACHEL
Today astronomers use airplanes to carry astronomical telescopes high above water vapor in the air.

PAUL
Airplanes are also being used to replace the first stage of rockets.

RACHEL
Fifty-five years ago in 1958, NASA created Project Mercury.

PAUL
Project Mercury had three basic goals.

RACHEL
First was to place an astronaut in orbit around Earth.

PAUL
Second was to observe how an astronaut performed in the weightlessness of space.

RACHEL
Third was to recover the astronaut and spacecraft safely in one piece after the mission.

PAUL
There were a total of six manned Mercury missions between 1961 and 1963.

RACHEL
Jupiter is the bright star to the moon’s upper left on the 18th.

PAUL
If you prop your binoculars on something steady, you may be able to make out all four of its Galilean Satellites.

RACHEL
A small telescope definitely will show them.

PAUL
In binoculars, you will see from lower left to upper right, the satellites are Ganymede, then Jupiter, followed by Io, Europa, and Callisto.

RACHEL
A telescope reverses this order.

PAUL
Io, Europa, and Callisto are close enough together that it may be difficult to cleanly separate them in your binoculars - steadiness is beneficial.

RACHEL
The moon passes very close to the M-67 star cluster on the evening of the 20th.

PAUL
Use binoculars and scan an area just to the moon’s upper right.

RACHEL
The cluster appears more impressive if you shift the binoculars to take the moon out of the field of view.

PAUL
Winter begins on December 21st at 10:11 AM.

RACHEL
At that time, Earth’s South Pole is facing directly towards the sun.

PAUL
This results in 24 hours of darkness for anyone living north of the Arctic Circle.

RACHEL
It is also the Northern Hemisphere’s shortest day.

PAUL
From now until summer, the days will begin growing longer and the nights shorter.

PAUL
That’s Idaho Skies for the third week of December. Next week is Christmas and we’ll give you a few targets for that new telescope.

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel...

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for December 8-15

RACHEL
Welcome to Idaho Skies for the second week of December. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
The moon is at first quarter on the 9th.

PAUL
The quarter moon is among the best times to look at the moon through your binoculars or small telescope.

RACHEL
Concentrate your efforts along the straight-line boundary between day and night, or what astronomers call the terminator.

PAUL
The terminator is where shadows cast by the rising sun stretch their longest length.

RACHEL
Since the terminator directly faces Earth at first quarter, the moon’s curvature doesn’t foreshorten the shadows.

PAUL
The combination of long shadows and no apparent foreshortening lets the terminator accentuate the smallest lunar surface features.

RACHEL
The Geminid meteor shower peaks on the night of the 13th and morning of the 14th.

PAUL
The moon is full in another three days, so in order to have your best views of this shower you’ll want to go outside after the moon sets at 4:00 AM.

RACHEL
Even though this is early for meteor watching, this shower is still worth your time.

PAUL
That’s because at its peak, 80 meteors per hour are visible from this shower.

RACHEL
In addition, the meteors are relatively bright and easy to see.

PAUL
Did you know that Geminid meteors appear yellowish in color rather than white like most meteors?

RACHEL
Something else that makes the Geminids unique is that their parent is an asteroid rather than a comet.

PAUL
This means the typical Geminid meteoroid is rocky and not fluffy comet dust.

RACHEL
You’ll know a meteor is a Geminid if it appears to radiate from a point high in the west-southwest.

PAUL
On the 14th, the moon is well placed between two large and bright star clusters.

RACHEL
The star clusters are the Pleiades and Hyades.

PAUL
This is an another great opportunity to use your binoculars.

RACHEL
That’s because the typical telescope has too much magnification.

PAUL
If you have a digital camera, tripod, and cable release, you might try taking a picture of this grouping.

RACHEL
The exposure time only needs to be a few seconds long.

PAUL
So using a tripod and cable release is important to keep the camera motionless during the exposure.

RACHEL
That’s Idaho Skies for the second week of December. The moon leads us to Jupiter next week and we’ll tell you how to see its largest moons through your binoculars.

PAUL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com. For Idaho Skies this is Paul...

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for the First Week of December

RACHEL
Welcome to Idaho Skies for the last week of December. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
December’s second meteor shower peaks on the 22nd.

PAUL
Meteors from the Ursid meteor shower appear to originate from the north and are at their best before the moon rises at 10:00 PM.

RACHEL
You can expect to see about a dozen faint meteors per hour from this shower.

PAUL
However, it has surprised astronomers with significantly higher rates on occasion.

RACHEL
When the moon rises on the morning of the 25th, look for a slightly orangish star to its left.

PAUL
That’s Mars.

RACHEL
Unfortunately, this is not a good time to view Mars through a telescope as it’s too far away and too small in diameter to show any detail.

PAUL
Every two years this changes however, so be patient.

RACHEL
The moon is last quarter on the 25th.

PAUL
So if you got a new telescope for Christmas, you can test it on the moon.

RACHEL
That is if you can wait until it rises after 2:00 AM on the 26th.

PAUL
Want to try out your new telescope on Saturn?

RACHEL
You can easily find Saturn on the morning of the 28th if you find the crescent moon first.

PAUL
It’s located in the low east.

RACHEL
At 6:00 AM, Saturn is the creamy-yellow star to the moon’s lower left.

PAUL
You will need a magnification of at least 25 times to see its rings.

RACHEL
But less magnification is required to see its largest satellite, Titan.

PAUL
Titan will appear star-like in your telescope

RACHEL
And it’s to Saturn’s upper right.

PAUL
Much closer to the moon is a star named Zubenelgenubi.

RACHEL
This star is a wide double star and it’s easy to split into two stars through binoculars.

PAUL
A thin crescent moon, just two days from new, appears in the morning sky on the 30th.

RACHEL
To see it, use binoculars and begin sweeping the low southeast at 6:45 AM.

PAUL
The moon will be less than a binocular’s field of view above the horizon.

RACHEL
But you’ll need to work quickly though.

PAUL
That’s because by 7:15 AM, the sky will begin brightening enough to make it difficult to see the moon.

RACHEL
Looking any later is dangerous too because you might sweep up the sun in your binoculars.

PAUL
That’s Idaho Skies for the last week of December. Join us next month for the space and astronomy events for Idaho.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com For Idaho Skies this is Rachel...

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Polaris is our Star for December

This month look for the star Polaris, the lucida of Ursa Minor or the Little Bear. Astronomers know Polaris as Alpha Ursae Minoris. In popular culture, we call this star the North Star and the Lode Star. Polaris gets these names because it is the guide to true north (as opposed to magnetic north). This is because Polaris appears almost straight up to anyone standing on the North Pole. The star is not the brightest star in the sky nor is it exactly true north. Polaris is the 40th brightest star in the sky and ¾ of a degree (1-1/2 moon diameters) away from the point of true north in the sky. In long duration photographs, Polaris makes a tiny little circle around the true North Pole while the other stars make larger and larger circles.

Astrophysicists classify Polaris as an F star, which means it’s a bit hotter than our sun (which is a G star). However, Polaris is an old F star and has begun fusing helium in its core (hydrogen is still being fused within Polaris, but this takes place within a shell surrounding the helium-fusing core). Strongly ionized helium in the star’s hot outer layer is opaque to light emitted by the star because helium absorbs much of it. This dims the star’s brightness since less light escapes the star. However, because of this absorption, the star’s outer layer gets hotter and starts expanding. Expansion of the outer layer eventually cools the helium in the outer layer, which then lets more of the star’s light escape. This then allows the star’s outer layer to shrink back to the point where it will get hot and begin expanding again. The process of becoming opaque and expanding followed by becoming transparent and contracting repeats itself over and over again. Since the star’s mass and energy generation is constant, the rate at which the star fluctuates in size and brightness also remains constant. Once astronomers know how long it takes Polaris to go through a cycle of brightening and dimming (this is the star’s period), they can determine the star’s true maximum brightness. By comparing Polaris’ apparent maximum brightness (how bright it looks from Earth) to its true maximum brightness, it is possible to calculate the distance to the star. Stars like Polaris are Cepheid variables, named after the Delta Cephei, the first one that astronomers discovered. Cepheid variables are bright and astronomers can use them to measure the distance to nearby galaxies.  


Polaris is an easy star to find since most people can locate the Big Dipper. The two stars at the end of the Big Dipper’s bowl are called the Pointers. A line drawn up from the Pointers just about runs into Polaris. Since Polaris is the star that marks the end of the Little Dipper’s handle, the rest of the constellation is located to the lower left of Polaris.

Transcript for the Last Week of November

RACHEL
Welcome to Idaho Skies for the last week of November. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
Since having passed greatest western elongation on the 17th, Mercury is approaching the sun and descending closer to the horizon.

PAUL
At the same time, Saturn is rising higher above the horizon every day.

RACHEL
The two planets pass their closest together on the morning of the 26th.

PAUL
To observe them, you’ll need to be outside between 6:30 AM when they rise and 7:00 when the sky gets too bright to see them.

RACHEL
The planets will appear as two very closely spaced stars low in the east-southeast.

PAUL
Brighter Mercury will be below slightly fainter Saturn.

RACHEL
Seldom are two planets less than one degree apart, so it should be an attractive sight visually and through binoculars.

PAUL
Both planets are too small and too far away to show detail through binoculars though.

RACHEL
However, a small telescope with a magnification of as little as 25 times will show the rings of Saturn.

PAUL
And its largest satellite, Titan.

RACHEL
As a bonus, to right of Mercury and Saturn is the slightly fainter star Zubenelgenubi.

PAUL
Zubenelgenubi is a star that your binoculars will easily resolve into two stars.

RACHEL
The first spacecraft to fly past Mars and return meaningful images was launched 49 years ago on the 28th.

PAUL
The spacecraft was Mariner 4, built by the Jet Propulsion Laboratory in Pasadena, California.

RACHEL
By chance, Mariner 4 over flew some of the oldest, most boring terrain of Mars.

PAUL
It’s 22 images of the Martian surface lead many space scientists to believe that Mars was similar to the moon, and therefore, without a chance of ever hosting life.

RACHEL
However, the images from Mainer 4 only covered 1 percent of the Martian surface.

PAUL
As later missions like Mariner 9 discovered, Mars has a variety of younger and more interesting terrain.

RACHEL
Some of these include a volcanic plateau called the Tharsis Montes and the largest rift valley in the solar system called Valles Marineris.

PAUL
Today, we even know today that some regions of Mars were carved by running water.

RACHEL
How much water, how long, and when are still open questions.

PAUL
Mars is visible on November mornings.

RACHEL
So look for the orange star located to the to the moon’s left on the morning of the 27th.

PAUL
That’s Idaho Skies for the last week of November. Join us next month for the space and astronomy events for Idaho.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com For Idaho Skies this is Rachel...

PAUL
...and Paul.

RACHEL
Dark skies and bright stars.

Transcript for November 17 to 24

PAUL
Welcome to Idaho Skies for the third week of November. We’re your hosts, Paul...

RACHEL
...and Rachel.

PAUL
The Leonid meteor shower peaks the morning of the 17th.

RACHEL
The Leonids are famous for producing spectacular showers every 33 years.

PAUL
Unfortunately, this is not one of those years and the moon is full on the 17th.

RACHEL
On average, you can expect to see 10 Leonids per hour in dark skies.

PAUL
Expect any Leonids to be swift and to originate from the east.

RACHEL
Did you know that during its most intense storm, the Leonids produced over 1,000 meteors per hour?

PAUL
That lead some people to believe the world was coming to an end.

RACHEL
Even people who were sleeping at the time of the shower became aware of it.

PAUL
That’s because of the commotion of their neighbors and from the bright light emanating from the shower’s numerous fireballs.

RACHEL
Don’t forget that Mercury is visible this week.

PAUL
On the 18th, the innermost planet reaches its greatest distance from the sun.

RACHEL
You can see this elusive planet at around 6:30 AM as the brightest star low in the east-southeast.

PAUL
If you observe Mercury this week, you can take a certain amount of pride knowing that you observed a planet that the famed Polish astronomer Nicholas Copernicus never saw.

RACHEL
We take the expansion of the universe for granted these days.

PAUL
Its discovery was the culmination of the work of two astronomers, Humason and Hubble.

RACHEL
Edwin Hubble was born 124 years ago on the 20th.

PAUL
Hubble first gained prominence with his discovery that some nebulae visible in telescopes were actually galaxies external to the Milky Way galaxy.

RACHEL
In other words, these were not glowing clouds of gas or small clusters of stars as many astronomers thought, but were instead vast islands of stars just like the Milky Way.

PAUL
Years later, Hubble discovered that most of these galaxies were expanding away from the Milky Way.

RACHEL
That doesn’t mean that the Milky Way is the center of the universe, however.

PAUL
In fact, any astronomer residing in any galaxy would detect all the other galaxies expanding away from that galaxy.

RACHEL
This observation is only possible if the space between the galaxies is expanding.

PAUL
By knowing the rate of this expansion, one can determine when all the galaxies were last together, and therefore, the age of the universe.

RACHEL
This is a difficult calculation to make and it has taken some extra detective work for astronomers to discover that the universe began 13.8 billion years ago.

PAUL
That’s Idaho Skies for the third week of November. Next week, we’ll tell you where to see three morning planets. 

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel...

PAUL
...and Paul.

RACHEL
Dark skies and bright stars.

Transcript for the First week of November

PAUL
Welcome to Idaho Skies for the first week of November. We’re your hosts, Paul...

RACHEL
...and Rachel.

PAUL
NASA launched the first spacecraft to visit the solar system’s innermost planet forty years ago on the 3rd.

RACHEL
NASA first sent Mariner 10 to Venus so it could use the planet’s gravity to alter its course to approach Mercury. This made Mariner 10 the first spacecraft to use a planet’s gravity to alter its trajectory.

PAUL
During a gravitational assist, a spacecraft steals some of a planet’s kinetic energy or the planet steals some of a spacecraft’s kinetic energy.

RACHEL
The amount of kinetic energy traded between the spacecraft and planet is so tiny that the effects on the planet won’t become obvious for billions of years.

PAUL
However, because of the spacecraft’s tiny mass, the impact can be huge for the spacecraft.

RACHEL
Mariner 10 needed to lose some of its kinetic energy because it had too much to orbit as close to the sun as its destination, Mercury.

PAUL
As Mariner 10 approached Mercury on March 29, 1974, it used Mercury’s gravity to alter its course and pass the planet two additional times.

RACHEL
Gravity wasn’t the only way Mariner 10 altered its orbit.

PAUL
That’s right. The sun’s light is so intense near Mercury that it can push a spacecraft around like a sailboat.

RACHEL
Because of the timing of the spacecraft passages, Mariner 10 was only able to photograph 45% of the planet’s surface.

PAUL
The rest of Mercury remained a mystery until the arrival of the Messenger spacecraft.

RACHEL
Images returned by Mariner 10 and Messenger reveal that Mercury’s surface shares a strong similarity to the moon.

PAUL
Idaho will get a glimpse of Mercury next week.

RACHEL
Before that, you can observe the Taurid meteor shower.

PAUL
The best night is on the 3rd, when the meteor shower reaches its peak intensity.

RACHEL
The moon will be nearly new on the 3rd making it easier to see the fainter members of this shower.

PAUL
You can expect to see around five meteors per hour after it gets dark.

RACHEL
Be sure to watch from a dark location where the effects of house and street lights are minimal.

PAUL
You can tell a meteor is a Taurid if it appears to originate from the east. After 3:00 AM, Taurids will appear to originate from nearly overhead.

RACHEL
Don’t let the fact that astronomers expect to see only five meteors per hour from this shower dissuade you from observing it.

PAUL
That’s because the Taurid meteors appear to contain a larger than usual share of large-sized particles.

RACHEL
You have a greater chance of seeing a fireball or bolide during this shower as a result of the larger meteoroids.

PAUL
The 9th would have been Carl Sagan's 79th birthday.

RACHEL
Most Idahoans know Sagan from his efforts to bring science to the public through his books and the PBS program, Cosmos.

PAUL
Sagan’s gift for science popularization is sorely missed.

RACHEL
Fortunately, we still have people like Neil deGrasse Tyson and Bill Nye.

PAUL
That’s Idaho Skies for the first week of November. Next week, Mercury will be visible to Idahoans early in the morning.

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel...

PAUL
...and Paul.

RACHEL
Dark skies and bright stars.

November's star, Alpheratz

This month look for the star, Alpheratz, the lucida, or brightest star of Andromeda. Alpheratz is one of the few stars connecting together two constellations. In this case, Alpheratz units the constellations of Andromeda and Pegasus. Alpheratz passes just south of the overhead position at 9:00 PM in early November and about two hours earlier in late November. Alpheratz is 97 light years, so if you know someone born in 1916, Alpheratz is his or her birthday star this year.

The surface temperature of Alpheratz is approximately 23,000 degrees F (making it what astronomers call a class B star). Being 150% hotter than the surface of our sun, Alpheratz produces significantly more ultraviolet radiation than the sun. In addition to producing more ultraviolet radiation, the star is producing 200 times more radiation than our Sun. To emit this amount of radiation, Alpheratz must be more massive than the sun. As a result of this additional mass, mathematical calculations predict that Alpheratz will live a shorter life than the Sun.

Alpheratz is not alone in space. It has a companion star with an orbital period of 97 days. Alpheratz is too distant and its companion too close for telescopes to see the two stars separately. Astronomers determine that stars like Alpheratz are binary stars by measuring the variations occurring in their combined spectra. The lines in the spectra of Alpheratz shift back and forth over a period of 97 days, giving away the fact that there are two orbiting each other in this period of time. We call stars like these spectroscopic binaries because of the way astronomers detect them.

Transcript for the Last Week of October

RACHEL
Welcome to Idaho Skies for the last week of October. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
On October 30th, 1938, the Mercury Theatre on the Air broadcasted a radio play.

PAUL
The producer was Orson Welles and he based his play on H. G. Wells’ War of the Worlds.

RACHEL
Orson Well’s Martian invasion was occurring that evening in Grover’s Mill, New Jersey.

PAUL
This was on the eve of war in Europe and many Americans found the news out of Europe unsettling.

RACHEL
Some feared that European events would drag the United States into another foreign war.

PAUL
Under this cloud uncertainty, the radio audience listened to news bulletins of strange events out of Grover’s Mill.

RACHEL
The news bulletins breaking into the ongoing music program told of Martian war machines attacking power plants and marching across the Hudson River.

PAUL
The panic that ensued was not as large as some stories have made it out to be.

RACHEL
Today we know Mars is a dead world.

PAUL
However, it may not have always been that way.

RACHEL
That’s right. Evidence collected by spacecraft point to a planet that in its past had large bodies of water.

PAUL
We don’t know yet how long conditions on Mars remained clement; however, it is possible that it was long enough for life to originate.

RACHEL
Any life that exists today is microbial at best.

PAUL
In order to discover it, spacecraft will need to drill deep into the planet’s surface or search through lava tubes.

RACHEL
On November 1st, Venus is at its greatest eastern elongation.

PAUL
The Evening Star will be visible in the west for two hours after it gets dark.

RACHEL
You can observe it sooner if you know where to look for it in the sunlit sky.

PAUL
You will find the planet low in the southwest when the sky gets dark at 7 PM.

RACHEL
Like Mars, some astronomers once considered Venus as potentially habitable.

PAUL
This was before they developed the tools to measure the temperature of Venus from Earth using microwave receivers.

RACHEL
Like Mars, Venus may have once been habitable billions of years ago.

PAUL
That’s before the sun warmed its surface to the point that a run away greenhouse ensued.

RACHEL
Today Venus is a scorching hot world with clouds of sulfuric acid and no water.

PAUL
Finally, this week, don’t forget to set your clock back on Saturday night, the second of November.

RACHEL
It’s the end of daylight saving time, so enjoy your extra hour of sleep.

PAUL
That’s Idaho Skies for the last week of October. Join us next month for the space and astronomical events in Idaho.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for the Third Week of October 2013

PAUL
Welcome to Idaho Skies for the fourth week of October. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
The moon appears between two star clusters on the evening of the 20th.

RACHEL
You’ll want to get your binoculars out for this astronomical event.

PAUL
After dark on the 20th, you’ll find the Pleiades star cluster left of the moon and the larger, sparser Hyades star cluster below the Pleiades.

RACHEL
You may know the Pleiades star cluster by its popular name, the Seven Sisters.

PAUL
In Greek mythology, the Seven Sisters were the daughters of Atlas, a Titan.

RACHEL
After the war between the Titans and the Zeus, king of the Greek gods, Atlas was forced to carry the heavens on his shoulders.

PAUL
That’s when Orion the Hunter began pursuing seven of his daughters.

RACHEL
This made Atlas most unhappy.

PAUL
Zeus, who cursed Atlas to carry the heavens, took pity on Atlas in this one regard and placed his daughters in the heavens for their protection.

RACHEL
In dark skies, people with good vision can see six stars in the Pleiades.

PAUL
And that it has the shape like a tiny dipper. However, this is not the Little Dipper.

RACHEL
Now look at them in your binoculars and you’ll see at least two dozen stars in the Pleiades.

PAUL
The stars in the Pleiades formed around 100 million years ago.

RACHEL
This was near the end of the reign of the dinosaurs.

PAUL
That means these stars are only two percent of the age of our solar system.

RACHEL
The Orionid meteor shower peaks on the night of October 20th and morning of the 21st.

PAUL
Typically, 21 meteors per hour are visible from this shower.

RACHEL
Unfortunately, the moon is just past full this morning.

PAUL
That means 2013 is not a great year to watch this meteor shower.

RACHEL
Your chances of seeing Orionid meteors occurs several days earlier when the moon sets while it’s still dark.

PAUL
Speaking of the moon, it traverses the outer edge of the Hyades star cluster on the night of the 21st.

RACHEL
In Greek mythology, the Hyades are also daughters of Atlas.

PAUL
Astronomers tell us that the stars in the Hyades are six times older than the neighboring Pleiades.

RACHEL
If you point your binoculars at the moon on the 21st, you’ll see that this star cluster spans an area much larger than the moon.

PAUL
You will also see that it has a distinct V shape.

RACHEL
You will see several dozen stars in this cluster in dark skies.

PAUL
The moon is just below Gemini on the morning of the 26th

RACHEL
To the moon’s left, you will see a very bright star that’s not a part of this constellation.

PAUL
It’s Jupiter and it is so bright that you can’t miss it.

RACHEL
Look at Jupiter through your binoculars and you will see three fainter stars forming a line with the brighter planet.

PAUL
These are its largest moons.

RACHEL
From the bottom-left to the top-right, you will see Callisto, Europa, Jupiter, and finally Io and Ganymede.

PAUL
However, Io and Ganymede are so close together they can’t be resolved as individual satellites.

RACHEL
That’s Idaho Skies for the fourth week of October. Next week we’ll discuss Mars and Venus.

PAUL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for 6 to 12 October

PAUL
Welcome to Idaho Skies for the second week of October. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
Early on the evening of the 8th, the young crescent moon forms a triangle with two other astronomical objects.

RACHEL
To the lower right of the moon is brilliant Venus.

PAUL
Even though Venus is not the planet closest to the sun, its surface is hotter than Mercury’s.

RACHEL
To the moon’s lower left is the other party in this trio, the star Antares.

PAUL
Antares is a super red giant star and the brightest star of Scorpius the Scorpion.

RACHEL
The trio of the moon, Venus, and Antares will be very low in the southwest at 8:00 PM.

PAUL
Find a location with a clear southwest horizon in order to maximize your viewing time of this alignment.

RACHEL
This is not the end of the action in the low west. Venus and Antares continue approaching closer to each other until next week.

PAUL
So you might want to keep an eye on this region of the sky even after the moon has left the scene.

RACHEL
The moon is passing through a thick section of the Milky Way on the 10th.

PAUL
This area of the Milky Way lies between Earth and the central bulge of the Milky Way galaxy.

RACHEL
Since its closer to the nucleus of the galaxy, it contains more star clusters and nebulae than any other part of the sky.

PAUL
Many of the star clusters and nebulae are visible in a pair of binoculars, if you observe them where the sky is clear and dark.

RACHEL
You’ll need to find a location away from light and let your eyes become adapted to the dark.

PAUL
Did you know that your eyes adapt to the dark by dilating your pupils.

RACHEL
This lets more light enter into your eye and then you can see fainter stars as a result.

PAUL
The process of getting dark adapted can take as long as 20 minutes for older adults.

RACHEL
After your eyes have adapted, begin scanning the region west of the moon with your binoculars.

PAUL
Be sure to scan both high and low.

RACHEL
In binoculars, the stars will remain pin points of light.

PAUL
Nebulae however will appear as hazy spots.

RACHEL
Some of the largest star clusters will appear as small sprinkles of fainter stars.

PAUL
Did you know that it was Galileo who first discovered the nature of the Milky Way?

RACHEL
In 1609, Galileo overheard news about the discovery of a new optical instrument invented in Holland.

PAUL
An ambassador claimed the instrument magnified the view of what ever it was pointed at.

RACHEL
Galileo quickly realized its operating principle and made one for himself.

PAUL
His first telescope only magnified three times.

RACHEL
In time however, he became expert at making lenses and eventually created a telescope capable of magnifying 30 times.

PAUL
So Galileo is not the inventor of the telescope, but he is one of the first to turn it towards the heavens, including the Milky Way.

RACHEL
And he was the first to publish the results so that the public could read about them.

PAUL
Galileo discovered that the nebulous appearing Milky Way became a multitude of stars in his telescope.

RACHEL
You can do the same this week with your binoculars.

PAUL
That’s Idaho Skies for the second week of October. Next week is the Hunter’s Moon.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript fior September 29th to October 5th

RACHEL
Welcome to Idaho Skies for the first week of October. We’re your hosts, Rachel…

PAUL
… and Paul.

RACHEL
The very thin crescent moon is located between Regulus, the brightest star of Leo the Lion, and Mars on the 1st.

PAUL
You’ll need to go outside at 6:00 AM to see this alignment.

RACHEL
Regulus, also known as Alpha Leonis to astronomers, is 77 light years away.

PAUL
So if you know someone who is 77 years old this year, Regulus is their birthday star.

RACHEL
Mars is too small and distant to show any detail in binoculars.

PAUL
And the moon will be so thin that binoculars won’t make out much detail on its surface.

RACHEL
Speaking of the moon, did you know the far side of the moon remained a mystery until 54 years ago this month?

PAUL
The Soviet Union placed the spacecraft Luna 3 into a very elliptical orbit.

RACHEL
At its farthest point from Earth, it passed behind the moon.

PAUL
As it passed  the moon on October 3, 1959, the 950 pound, solar-powered Luna 3 snapped several poor quality images of the moon’s far side.

RACHEL
This was back in the days of film, so the Luna 3 had to develop the negatives itself.

PAUL
As it passed close to Earth again, Luna 3 scanned the images and transmitted them as a fax.

RACHEL
Remember that the moon has a far side, but not a dark side.

PAUL
That’s right; the far side gets daylight for two weeks per month, so it’s no darker than the near side that we can see.

RACHEL
The reason the moon has a far side is that it is tidally locked.

PAUL
This happens to all small astronomical bodies that are orbiting close to massive astronomical bodies.

RACHEL
It’s happening now to Mercury because of its small distance from the sun.

PAUL
The hot Jupiter exoplanets that astronomers have discovered around other stars are likely tidally locked also.

RACHEL
The moon is new on the 4th.

PAUL
This means the first week of October is a great time for observing faint fuzzy objects through your binoculars or telescope.

RACHEL
Unfortunately, it also means that the moon will be near full at the peak of the Orionid meteor shower.

PAUL
In place of observing meteors, try observing the Zodiacal Light this month.

RACHEL
It appears as a faint glowing pillar of light in the east at least two hours before sunrise.


PAUL
Unlike the dawn, the Zodiacal Light forms a tall triangular-shaped pillar that tilts slightly towards the south.

RACHEL
It’s the reflection of sunlight off of comet dust orbiting the sun.

PAUL
You don’t have to be in a hurry to see the Zodiacal Light; you have until the 17th to see it.

RACHEL
After then, the moon’s light will brighten the sky and interfere.

PAUL
That’s Idaho Skies for the first week of October. Next week the moon passes through the best part of the Milky Way, so get your binoculars ready.

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

This month look for the star Deneb, the brightest star of the constellation of Cygnus the Swan. The word Deneb is Arabic for tail, referring to the fact that the star represents the swan’s tail. Deneb is the 19th brightest star in the sky. It, along with the stars Vega and Altair form the Summer Triangle. The Summer Triangle is an asterism and not a constellation. The Summer Triangle passes directly overhead at 9:00 PM in early September.

Deneb is somewhere between 1,600 and 2,600 light years away. This makes Deneb the most distant star visible without a telescope. The reason that we can see it from so far away is that it is a massive star. It has 20 times the mass of the Sun and a diameter 200 times greater than our Sun’s diameter. If Deneb were to replace our Sun, it would fill the orbit of Earth. Deneb’s large mass makes it 250,000 times brighter than the Sun. Deneb has a surface temperature of 16,000 degrees Fahrenheit, or white hot. For Earth to maintain a mild climate while in orbit around Deneb, Earth would have to orbit Deneb at a distance ten times greater than the distance between Pluto and the Sun. The supergiant Deneb is so hot that it is blowing material off of its surface at a rate a thousand times faster than the Sun. This large mass loss is not sufficient, however, to reduce Deneb’s mass down to safe levels before its too late. Within a few million years, Deneb will end its life in a supernova explosion.     

Deneb appears directly overhead at 9:30 PM in early September and at 8:30 PM by the end of the month. Look for Deneb as the faintest and most northeast member of the Summer Triangle.

Transcript for August 25th to 31st

PAUL
Welcome to Idaho Skies for the last week of August. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
Did you know that Idaho has a 25” telescope that’s opened to the public?

RACHEL
Twenty five inches is the diameter of the telescope’s mirror.

PAUL
The larger a telescope’s mirror, the more star light it gathers and focuses on your eye.

RACHEL
That means the fainter the objects that you can see through the telescope.

PAUL
The telescope and its observatory are located at the Bruneau Dunes state park.

RACHEL
It’s located there because some of the darkest skies in the Treasure Valley are located at the park.

PAUL
So if you are camping overnight at Bruneau Dunes, consider adding a side trip to the observatory.

RACHEL
Prior to opening the observatory, the park gives a space and astronomy presentation at the Steele Reese Education Center next door to the observatory.

PAUL
The observatory then remains open for several hours

RACHEL
The last quarter moon is next to the Hyades star cluster on the morning of the 28th.

PAUL
Look in the east after midnight to see this grouping.

RACHEL
They’ll be close enough together that the moon and Hyades will fit within your binoculars at the same time.

PAUL
The Pleiades star cluster, which is even more popular than the Hyades, is above the moon and farther away from the moon than the Hyades are.

RACHEL
The waning crescent moon and Jupiter form a nice binocular pair on the morning of the 31st.

PAUL
Recall that this duo passed close to each other on the morning of the 3rd.

RACHEL
This time however, Jupiter and the moon will be a degree closer together.

PAUL
And best of all, they are visible in darker skies.

RACHEL
If you use binoculars to look at Jupiter, you will notice at least two stars to the upper right of Jupiter.

PAUL
These aren’t stars, they’re satellites.

RACHEL
Use a small telescope instead of binoculars and you will see four stars to the upper right of Jupiter.

PAUL
From Jupiter outwards, the satellites are Callisto, Io, Ganymede, and Europa.

RACHEL
Callisto is the largest satellite in the solar system.

PAUL
That’s right. It’s 50% larger than our moon.

RACHEL
When you use your binoculars to observe Jupiter, you are making an observation similar to Galileo’s 1609 observation of Jupiter.

PAUL
Galileo was amazed to see the Jovian moons that we take for granted today.

RACHEL
He would be amazed to see them in the way our visiting spacecraft have.

PAUL
That’s Idaho Skies for the last week of August. Join us next month for the space and astronomical events in Idaho.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for 18 - 24 August

RACHEL
Welcome to Idaho Skies for the third week of August. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
The moon is full on the 20th. The full moon in August is called the Dog Days or Sturgeon Moon.

PAUL
The full moon means its light will wash out all the fainter stars.

RACHEL
That makes the full moon a bad time to do any star gazing by eye or with binoculars.

PAUL
Did you know Idaho has three planetariums open to the public?

RACHEL
That’s right. The first is located at BYU Idaho in Rexburg.

PAUL
The BYU Idaho planetarium gives presentations every Thursday evening.

RACHEL
Because of summer vacations, August is the only month that they are closed.

PAUL
So keep your eyes open for the resumption of shows next month.

RACHEL
A link to the planetarium can be found on the campus website, www.byui.edu

PAUL
The Wittenberger planetarium at the College of Idaho in Caldwell is the second Idaho planetarium.

RACHEL
The College of Idaho planetarium typically gives shows on the third Wednesday of the month.

PAUL
However, you need to make a reservation in order to attend its presentations.

RACHEL
Call the mathematics and physical sciences department to make your reservation.

PAUL
You’ll find a link to the planetarium at the college of Idaho website, www.collegeofidaho.edu

RACHEL
Idaho’s largest planetarium is located at the College of Southern Idaho campus in Twin Falls.

PAUL
The Faulkner gives more presentations than any other Idaho planetarium.

RACHEL
You’ll find shows on Tuesday and Friday at 2, 3:30, 7, and 8:15 PM.

PAUL
… Wednesday and Thursday at 2 and 3:30 PM.

RACHEL
… and Saturday at 2, 4, 7, and 8:15 PM.

PAUL
This summer the Faulkner planetarium is presenting shows like Light Years from Andromeda, Star Signs, and Lifestyles of the Stars.

RACHEL
You’ll find the Faulkner Planetarium schedule on the College of Southern Idaho website, www.csi.edu.

PAUL
Idaho is also home to three major astronomy clubs.

RACHEL
These include the Boise Astronomical Society, the Magic Valley Astronomical Society, and the Idaho Falls Astronomical Society.

PAUL
Check their respective websites for meeting times and places.

RACHEL
Joining one of these astronomy clubs is a great way to learn about astronomy.

PAUL
That’s Idaho Skies for the third week of August. Next week, the moon passes very close to Jupiter for the second time this month.

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for August 11 - 17

PAUL
Welcome to Idaho Skies for the second week of August. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
The night of the 11th and morning of the 12th is the peak of the Perseid meteor shower.

RACHEL
This meteor shower is best viewed after midnight.

PAUL
That’s when Idaho faces directly into the shower.

RACHEL
It’s similar to driving into a snow storm.

PAUL
That’s right. The rate of snowfall appears to be greater when the car’s direction of travel is into the direction that the snow is falling.

RACHEL
Perseid meteors will appear to radiate from the northeast.

PAUL
Plan to spend some time observing meteors because this shower is very dependable.

RACHEL
You may see more than 30 meteors per hour. And many will be bright and may even flare.

PAUL
136 years ago on the 12th, astronomer Asaph Hall detected a small star-like object close to the planet Mars.

RACHEL
It turned out to be a rock eight miles across orbiting the planet.

PAUL
This was the first Martian satellite that astronomers discovered.

RACHEL
Hall named his discovery Deimos, after one of the twin son’s of the god Mars.

PAUL
The name means terror in Latin.

RACHEL
Because of its small mass, a 12 mile per hour sprint is enough to launch your self off the surface of Deimos and into an eternal orbit around Mars.

PAUL
It wasn’t much later before Hall discovered a second satellite of Mars.

RACHEL
Some people were not surprised to discover that Mars had two satellites.

PAUL
This is because they saw that the two satellites around Mars fit a geometric progression between Earth with one satellite and Jupiter with four satellites.

RACHEL
Jonathon Swift makes mention of this in his story of Gulliver’s Travels.

PAUL
Today we know that Jupiter has far more than four satellites and the fact that Mars has two satellites is just a coincidence.

RACHEL
Speaking of moons, a far less terrifying one appears close to Spica and Saturn on the nights of the 11th and 12th respectively.

PAUL
Both objects will be around three degrees from good ol’ Luna on their night of closest approach.

RACHEL
The best time to look for both of these close approaches is between 10:15 and 10:45 PM.

PAUL
The moon reaches the first quarter phase on the 14th.

RACHEL
As always, this is a great phase for observing the moon with your binoculars or telescope.

PAUL
Focus most of your attention on the terminator, or boundary between day and night, for the greatest amount of visible detail.

RACHEL
The waxing gibbous moon is centered in the Milky Way on the night of the 16th.

PAUL
Search the sky all around the moon with your binoculars and you will find star clusters and nebulas, or clouds of glowing gas.

RACHEL
While binoculars are fine for this, a low power telescope with a wide field of view is even better.

PAUL
Mars passes its closest to Pollux, the brightest star in Gemini on the 17th.

RACHEL
If you have the time, you should start your observations of Mars and Pollux one week earlier.

PAUL
You will notice that Pollux appears higher every morning, but that Mars appears to remain nearly stationary with respect to the horizon.

RACHEL
In time, Earth will begin catching up to Mars.

PAUL
Then Mars will begin appearing in the evening sky rather in the morning sky.

RACHEL
That’s Idaho Skies for the second week of August. Next week we’ll tell you about the planetariums in Idaho. 

PAUL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for August 4 - 10

RACHEL
Welcome to Idaho Skies for the first week of August. We’re your hosts, Rachel…

PAUL
… and Paul.

RACHEL
Our best views of Mercury occur during the first half of the month.

PAUL
That’s because Mercury reached greatest western elongation back on July 30th.

RACHEL
Greatest western elongation occurs when Mercury or Venus reaches its greatest angle away from the sun in the eastern morning sky.

PAUL
Since it just past greatest elongation, Mercury is now approaching closer to the sun.

RACHEL
However, the sun is rising later each morning.

PAUL
That means Mercury’s distance above the horizon prior to sunrise remains nearly unchanged for several days.

RACHEL
Look for Mercury low in the east-northeast for the next two weeks.

PAUL
The moon is just above the star Aldebaran on the morning of the 1st. Many listeners know Aldebaran as the orange eye of Taurus the Bull.

RACHEL
Their separation is just over two degrees, or four lunar diameters. Use your binoculars for observing this pair.

 PAUL
The moon is a waning crescent on the 3rd. This same day, it also makes a close approach to Jupiter.

RACHEL
Jupiter will be obvious as the bright star to the left of the moon. They both will fit within the field of view of your binoculars.

PAUL
On the 4th, the moon passes close to Mars.

RACHEL
Look for them in the low eastern sky in the morning at 5:45 AM.

PAUL
Mars will appear as a yellowish-orange star located to the upper left of the moon.

RACHEL
The very thin crescent moon should display a strong Earthshine.

PAUL
Many people are unfamiliar with Earthshine.

RACHEL
Earthshine is just sunlight reflecting from the moon.

PAUL
However, before the sun’s light reflected off the moon, it first reflected off Earth.

RACHEL
This reflected Earth light faintly illuminates the dark portion of the moon, which is why it is called Earthshine.

PAUL
When you look at the moon, you will see a brightly illuminated crescent surrounding the rest of its faintly illuminated disk.

RACHEL
If you were an astronaut was standing on the Earthshine portion of the moon, it would be dark because the sun had not risen yet.

PAUL
However, overhead would be Earth.

RACHEL
Earth would appear as a nearly full blue-white disk four times larger than the moon appears in our sky and many times brighter.

PAUL
So sunlight reflecting off Earth more brightly illuminates the moon’s surface than the full moon illuminates Earth’s surface.

RACHEL
On the morning of the 8th, Mercury forms a straight line with the stars Castor and Pollux, the brightest stars of Gemini.

PAUL
You’ll need to go outside a little before 6:00 AM and look in the very low east-northeast.

RACHEL
If you go outside much earlier, Mercury will not have risen high enough for you to see.

PAUL
And if you go outside a little after 6:00 AM, the sun will begin brightening the sky too much to see Mercury clearly.

RACHEL
The very thin waxing crescent moon is located five degrees away from Venus on the evening of the 9th.

PAUL
Look low in the west, as the moon is only three days old.

RACHEL
This ought to be an attractive site in your binoculars.

PAUL
That’s Idaho Skies for the first week of August. Next week is one of the year’s best meteor showers.  

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

This month look for the star Rasalhague in the constellation of Ophiuchus the Serpent Bearer. Rasalhague is the brightest star of this large and dim constellation, which has the shape of a simple house and reaches nearly to the zenith. Ophiuchus is located in the south, just above Scorpius on August evenings and Rasalhague is the star at the top of the constellation.

In Greek myth, Ophiuchus is Asclepius the healer. He was born to a mortal mother and his father was the Greek god Apollo. In his youth, Asclepius was given to Chiron the centaur to raise. It was Chiron who trained his adopted son to be healer. Asclepius became such a great healer that he brought several of his dead patients back to life. To prevent him from going too far, Zeus hurled a thunderbolt and killed Asclepius. His father Apollo complained about the death of his son, so Zeus made Asclepius immortal and placed him in the sky as Ophiuchus.    

Rasalhague (also called Alpha Ophiuchi and 55 Ophiuchi) is Arabic for "the Head of the Serpent Collector."  The star is 47 light years away. Therefore, the light you see from Rasalhague tonight left in 1966. Rasalhague is a double star, but its companion is so close that even a telescope can’t resolve them as separate stars. Rasalhague is spectral type A5 (white in color) and has a surface temperature of 18,000 degrees (compare to 5,800 degrees for the sun). That makes Rasalhague twice as hot and 25 times brighter than our sun. Rasalhague recently (in stellar years) stopped converting hydrogen into helium. Its higher core temperature is permitting the star to generate energy by fusing the helium ash in its core into carbon and oxygen.

Transcript for June 16 - 22

RACHEL
Welcome to Idaho Skies for the third week of June. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
The moon is first quarter on the 16th.

PAUL
That means it’s time to dust off your old pair of binoculars and take a gander at the moon.

RACHEL
Craters are noticeable in your binoculars, especially in the southern half of the moon.

PAUL
Your best lunar views come from bracing your arms on something sturdy, like a tree or fence.

RACHEL
That way the shaking in your arms will not blur the view.

PAUL
On the 18th, the moon sits between the star Spica and the planet Saturn.

RACHEL
Spica is closer to the moon while Saturn is farther away.

PAUL
You’ll be able to see either the moon and Spica together in binoculars or the moon and Saturn together, but not all three simultaneously.

RACHEL
When you observe Saturn, you’ll see that the star Kappa Virginis in the constellation Virgo is close to Saturn’s upper right.

PAUL
But they’re not close in space. Saturn is 76 light minutes away while Kappa Virginis is 224 light years away.

RACHEL
So the light you see from Saturn only left an hour and fifteen minutes ago while the light of Kappa Virginis left in the year 1789.

PAUL
Thirty years ago on the 18th, the United States launched the first American woman into Earth orbit aboard the Space Shuttle.

RACHEL
Sally Ride was 32 years old when she traveled to space and she still remains the youngest American to travel into space.

PAUL
Sally spent a total of two weeks in space during her two Space Shuttle flights. Both of her flights were on board the Space Shuttle Challenger.

RACHEL
Sally was not the first woman in space, however. She was preceded into space by Soviet cosmonauts Valentina Tereshkova in 1963 and Svetlana Savitskaya in 1982.

PAUL
This week Venus is rising higher above the horizon and Mercury is approaching the horizon.

RACHEL
So the two inner planets cross paths once again on the evening of June 20th.

PAUL
Mercury will be to the lower left of brighter Venus.

RACHEL
They’ll be close enough together that both will be visible together in your binoculars.

PAUL
Begin looking for the pair of planets by 10:00 PM, after the sun has set.

RACHEL
While you’re searching for Venus and Mercury, you may notice there are two stars above and to the right of Venus.

PAUL
These are the brightest two stars of Gemini, Pollux and Castor.

RACHEL
Summer in the northern hemisphere begins late on the evening of the 20th.

PAUL
That means on the 20th, daylight lasts it’s longest for the year.

RACHEL
In Boise, our first day of summer will be 15 hours and 23 minutes long.

PAUL
That’s Idaho Skies for the third week of June. Next week we’ll discuss the full moon, its proximity to Earth, and what effect this will have on us.

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for June 9 - 15

PAUL
Welcome to Idaho Skies for the second week of June. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
On the evening of the 10th, the young crescent moon passes very close to Mercury and Venus.

RACHEL
You’ll need to look for this trio of astronomical objects after 10:00 PM, but before 10:30. You’ll need a clear west-northwestern horizon to see them, as they will be low.

PAUL
The 10th also marks the tenth anniversary of the launch of the Spirit Mars Rover.

RACHEL
Spirit was one of two solar-powered rovers launched to the red planet in 2003.

PAUL
For six years, Spirit traversed the Martian surface looking for evidence of water in Mars’ past.

RACHEL
The rover traveled nearly five miles during its search and made multiple measurements of the Martian rocks near the Columbia Hills.

PAUL
Spirit’s instruments detected slight chemical alterations in the composition of the outer layers of rocks.

RACHEL
It also found a type of chemical called sulfates in the Martian soil.

PAUL
These results indicated that water was present in the Martian past.

RACHEL
However, the amount was small compared to the amount of water found on Earth.

PAUL
Spirit’s mission ended after it became stuck in soft Martian sand.

RACHEL
Unable to extract itself from the loose sand, Spirit couldn’t properly orient its solar array for the approaching winter.

PAUL
The limited amount of sunlight available during the winter prevented Spirit’s solar array from acquiring enough power to survive the brutal cold.

RACHEL
On June 12th, Mercury is at its greatest eastern elongation.

PAUL
Elongation is a property of the orbits of inner planets and not outer planets.

RACHEL
Inner planets, which astronomers call inferior planets are those that orbit closer to the sun than Earth.

PAUL
Like Mercury and Venus.

RACHEL
And superior planets are those that orbit the sun farther than Earth.

PAUL
Since inferior planets reside closer to the sun than Earth, we will never see them in the sky opposite of the sun.

RACHEL
The greatest distance away from the sun that we see an inferior planet is called its greatest elongation.

PAUL
Because of its small orbit, Mercury can only travel 24 degrees away from the sun.

RACHEL
That sounds impressive. After all, 24 degrees is nearly 1/3rd of the distance from the horizon to overhead.

PAUL
That would be correct if Boise was located on the equator. However, at a latitude of 43 degrees north, Mercury’s orbit around the sun is very slanted with respect to our local horizon.

RACHEL
So how far above the horizon will Mercury appear when its 24 degrees from the sun?

PAUL
Our solar system’s smallest planet will only appear ten degrees above horizon at 10:00 PM. That means by 10:45, the planet will be all but impossible to see.

RACHEL
Hey, the earliest sunrise this year occurs on the 13th!

PAUL
That means from now until mid December, the sun will set earlier each night.

RACHEL
That’s Idaho Skies for the second week of June. Next week the moon passes close to Saturn, so you will have more than just Mercury and Venus to observe.

PAUL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

This month look for the star Arcturus, the lucida of the constellation of Bootes, the Herdsman. Arcturus is located 37 light years from earth. Therefore, if you were born in 1976, Arcturus is your birthday star this year. The word, Arcturus, means “Bear Guardian” and is a reference to its closeness to the Great Bear, or Ursa Major. As the constellation of the Big Bear wheels around the sky, the bright star Arcturus follows closely behind.  

The light of Arcturus opened the 1933 World’s Fair in Chicago. At that time, the best measurement of the distance to this star pegged it at 40 light years. Since the previous World’s Fair in Chicago occurred forty years earlier, the starlight seen from Arcturus at the opening of the 1933 fair had left the star during the last fair. To open the 1933 World’s Fair, a large telescope lens focused the Arcturian starlight on a photocell (a light-sensitive resistor). The electrical signal generated by the star’s light shining on the photocell was used to switch on the lights of the fair. 

Arcturus is a spectral type K star, meaning its cooler than our sun and produces less light per square foot of surface. Instead of being yellow like our sun (which is a G spectral type), Arcturus is a cooler orange. However, because of its larger diameter, Arcturus shines over 100 times more brightly than our sun. If its infrared radiation is included, then the star is over 200 times brighter than our sun. It would take 26 of our suns to span the diameter of Arcturus. If the star replaced the sun in our sky, it would cover an area of the sky two times larger than the palm of your outstretched hand. The surface of Arcturus would reach one-quarter of the way to the orbit of Mercury. Of course, the larger mass, diameter, and radiation from Arcturus would end all life on Earth with the possible exception of bacteria living far underground.  

To find Arcturus, follow the bend of the handle of the Big Dipper. An arc drawn from the end of the Dipper’s handle (actually the Large Bear’s tail) leads you to Arcturus. In June, Arcturus passes almost directly overhead.    

Transcript for June 2 - 8

RACHEL
Welcome to Idaho Skies for the first week of June. We’re your hosts, Rachel…

PAUL
… and Paul.

RACHEL
Now is the time to observe Mercury, Venus, and Jupiter.

PAUL
Our solar system’s two innermost planets remain close to Jupiter and all three are visible in the western evening sky.

RACHEL
Since Jupiter and Venus are so bright, they make it easier to locate Mercury.

PAUL
To see them, look low in the west-northwestern horizon about 30 minutes after sunset on the 1st.

RACHEL
That evening, Jupiter, Venus, and Mercury will form a straight line that is inclined towards the upper-left.

PAUL
Jupiter will be the lowest and very near the horizon. Venus is brighter and is located to Jupiter’s upper left.

RACHEL
To locate Mercury, just draw a straight line upwards from Jupiter to Venus. Mercury is located the same distance above Venus.

PAUL
Venus continues climbing higher above the horizon this summer.

RACHEL
Jupiter, on the other hand, is passing behind the sun soon and will reappear in the morning sky in another month.

PAUL
What about Mercury? What is its motion in June?

RACHEL
Mercury will climb a bit higher above the horizon until June 10th. Then it will begin approaching the sun, from Earth’s perspective.

PAUL
On the 4th, Venus is just above a cluster of stars named M-35.

RACHEL
It will be difficult to see very well because the sun will have recently set and it will still be dawn.

PAUL
You’ll need to search for this star cluster just below Venus after 10 PM.

RACHEL
However, you won’t have long, Venus sets at 10:30.

PAUL
Speaking of dawn, did you know that there are three types of twilight?

RACHEL
That’s right. The first is called civil twilight. Civil twilight ends when the center of the sun is 6 degrees below the horizon.

PAUL
At the end of civil twilight, we can only see the brightest stars. However, it is dark enough that state laws require us to turn on our car headlights.

RACHEL
The second is nautical twilight. This ends when the center of the sun is 12 degrees below the horizon.

PAUL
At the end of nautical twilight, sailors cannot navigate using observations that require them to see the horizon; the horizon is too dark to distinguish from the sky.

RACHEL
The last is astronomical twilight. At the end of astronomical twilight, the center of the sun is 18 degrees below the horizon.

PAUL
At the end of astronomical twilight, the sky is as dark as it will get. We can see the faintest stars.

RACHEL
The moon is new on the 8th, so you won’t see it for a day or two at best.

PAUL
However, it’s a good time to see faint objects through your telescope or binoculars.

RACHEL
That’s Idaho Skies for the first week of June. Join us next week to hear more about the innermost planets of our solar system.

PAUL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for May 19 to 25

PAUL
Welcome to Idaho Skies for the fourth week of May. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
May 20th is the 25th anniversary of the launch of Pioneer Venus 1. After entering orbit, it spent a decade exploring Venus.

RACHEL
It used a simple radar system to map the planet’s surface.

PAUL
Thick opaque clouds cover Venus and radar is the only way to penetrate this layer of sulfuric acid clouds.

RACHEL
Spica is the bright star to left of moon on the evening of the 21st.

PAUL
The separation between them is 3½ degrees; therefore, they will both comfortably fit within your binoculars at the same time.

RACHEL
Even though they appear close together, their distance apart in three dimensions is immense.

PAUL
That’s right. It takes light only 1½ seconds to travel the distance between us and the moon. Spica on the other hand requires a trip of 263 years.

RACHEL
On the 22nd, the moon is your guide to Saturn.

PAUL
The ringed planet will appear to the upper left of the moon late that evening.

RACHEL
While the moon is a spectacular binocular and telescope object, Saturn requires a telescope.

PAUL
However, even a small telescope at low power is enough to show the planet’s ring system and largest satellite, Titan.

RACHEL
Another planetary event is taking place on the other side of the sky.

PAUL
For the next week, Jupiter, Venus, and Mercury are approaching one another.

RACHEL
They’re close to the west-northwestern horizon. So you’ll need to look around 9:30 PM. If you find them, all three will fit within your binoculars at the same time.

 PAUL
And their configuration will get more tightly grouped over the next four days.

RACHEL
Five years ago on the 25th, the Phoenix lander arrived on Mars.

PAUL
The mission of the Phoenix lander was to explore the role and history of water on the Martian surface.

RACHEL
Its landing site was located in the arctic region of Mars where scientists believed water would accumulate as ice.

PAUL
A camera on the lander showed that its landing engines blew loose dust off of a layer of ice buried just beneath the Martian soil.

RACHEL
What appears to be water drops, were seen clinging to the landing legs before they eventually sublimated away.

PAUL
No one expected to see drops of liquid water on Mars, as its atmospheric pressure is far too low for water to exist in the liquid phase.

RACHEL
One reason that water might be able to exist for a short time as a liquid is that the Martian artic soil contains a perchlorate salt.

PAUL
Perchlorate can act as antifreeze and that makes liquid water a little more stable in extreme conditions.

RACHEL
Signs gathered by this lander and other spacecraft now indicate that the planet once had a wetter climate.

PAUL
That’s Idaho Skies for the fourth week of May. Join us next week to hear about two great opportunities to observe four planets.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for May 12 to 18

RACHEL
Welcome to Idaho Skies for the third week of May. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
The moon is making an evening appearance this week.

PAUL
It takes two or three days after new moon for it to get far enough away from the sun that we can easily observe it after dusk.

RACHEL
On the evening of the 12th, the moon will be a crescent and just to the left of Jupiter. Both will be close enough together to be seen at the same time in your binoculars.

PAUL
Try looking for them around 10 PM.

RACHEL
You might notice a star very close to the moon on the right.

PAUL
That’s the star Zeta Tauri, which is 418 light years away.

RACHEL
Do you want to learn to identify the constellation of Gemini?

PAUL
The celestial twins stand on top of the moon on the 13th.

RACHEL
Gemini will appear as two parallel columns of stars stretching to the upper right of the moon.

PAUL
Some of our listeners may remember when the United States launched its first space station, Skylab.

RACHEL
The day was May 14th, 1974. Initially, the launch seemed to go well.

PAUL
The outer surface of Skylab acted as a micrometeoroid shield. Engineers designed it to extend a little distance away from the main body of the space station after it entered orbit.

RACHEL
Unfortunately, the shield deployed from the space station during its ascent to orbit.

PAUL
This permitted the rush of the atmosphere to rip it and one of Skylab’s solar arrays off the space station.

RACHEL
Because of the repairs performed by the first crew of astronauts to visit Skylab, the mission of the space station was able to continue.

PAUL
Among their experiments, astronauts made observations of the sun with an array of several telescopes.

RACHEL
Because the Space Shuttle launched several years later than planned, Skylab was not rescued and refurbished before reentering the atmosphere in July 1979.

PAUL
The oldest star cluster easily visible to our eye through binoculars is M-67 in Cancer the Crab.

RACHEL
The stars in this cluster are about four billion years old, or a little younger than our solar system.

PAUL
On the evening of the 16th, the moon is your guide to this cluster.

RACHEL
Use binoculars and search for a hazy spot to the right of the moon.

PAUL
The cluster spans an angle close to the moon’s size.

RACHEL
The heart of Leo the Lion is the star Regulus.

PAUL
It’s the yellowish-orange star above the first quarter moon on the night of the 17th.

RACHEL
While it doesn’t look like much to our eye, Regulus is quite a large star. It has a diameter five times greater than the sun’s and spins much faster.

PAUL
And we mean fast. Regulus rotates once in 16 hours versus the 24 days it takes our sun to rotate once.

RACHEL
Because of its large girth and short rotational period, the surface of Regulus travels at nearly 70,000 miles per hour at its equator.

PAUL
That high speed creates a budge at the equator. The bulge makes Regulus 33% wider across its equator than across its poles.

RACHEL
That’s Idaho Skies for the third week of May. Next week, you can locate Saturn and the star Spica next week with a little help from the moon.

PAUL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for May 5 to May 11

PAUL
Welcome to Idaho Skies for the second week of May. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
The Eta Aquarid meteor shower reaches its peak on the 5th.

RACHEL
This meteor shower is visible for at least a week before and after its peak, which is good because the moon’s light is going to interfere.

PAUL
The moon’s light is not the only strike against this shower.

RACHEL
That’s right. It’s radiant, or the point in the sky where the meteors appear to radiate from, is close to the horizon in the Northern hemisphere.

PAUL
This means the meteor shower is much better south of the equator.

RACHEL
Did you know that the parent of the Eta Aquarid meteor shower is comet Halley?

PAUL
The Eta Aquarids is one of the two showers that originate from this comet.

RACHEL
So if you observe meteors from this shower this week, you’re watching dust from comet Halley vaporizing dozens of miles overhead.

PAUL
In dark skies and with no moon, you can expect to see around ten swift meteors per hour from this shower.

RACHEL
You’ll know you’ve seen an Eta Aquarid meteor if it originated from the low east.

PAUL
Even neater, a sizable portion of these meteors are expected to leave trains.

RACHEL
Meteor trains are the glowing trails left behind a meteor’s passage through the atmosphere. They can last from a few seconds to several minutes.

PAUL
Astronomers do not fully understand the mechanism responsible for meteor trains. However, they know that some of it consists of energetic atoms.

RACHEL
The high energy of the atoms and ions in the meteor train cause them to glow.

PAUL
If you see a long lasting meteor train, you may notice that its shape changes over time. Part of the reason is that high altitude winds are blowing the train in different directions

RACHEL
The moon is new on the 9th.

PAUL
At new moon, the moon’s orbital path carries the moon closest to the sun.

RACHEL
Since the moon’s orbit is tipped five degrees relative to Earth’s equator, the moon often passes over or below the sun at new.

PAUL
If there were no tilt in the moon’s orbit, then every new moon would result in a solar eclipse.

RACHEL
Fortunately, this month, the moon will indeed pass in front of the sun. The solar eclipse will only be visible in Australia, however.

PAUL
The moon will be 24 hours old on the evening of the 10th.

RACHEL
It will be difficult to see, but this is an opportunity to search for a very young crescent moon.



PAUL
Use binoculars and look just left, or south of Venus, very low in the northwestern sky right after sunset.

RACHEL
If you can find the moon, it will be just a sliver and will not even span half a circle.

PAUL
That’s Idaho Skies for the second week of May. Next week the young crescent moon leads us to a very old star cluster visible in binoculars. 

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.

Transcript for May 12 to May 19

RACHEL
Welcome to Idaho Skies for the third week of May. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
The moon is making an evening appearance this week.

PAUL
It takes two or three days after new moon for it to get far enough away from the sun that we can easily observe it after dusk.

RACHEL
On the evening of the 12th, the moon will be a crescent and just to the left of Jupiter. Both will be close enough together to be seen at the same time in your binoculars.

PAUL
Try looking for them around 10 PM.

RACHEL
You might notice a star very close to the moon on the right.

PAUL
That’s the star Zeta Tauri, which is 418 light years away.

RACHEL
Do you want to learn to identify the constellation of Gemini?

PAUL
The celestial twins stand on top of the moon on the 13th.

RACHEL
Gemini will appear as two parallel columns of stars stretching to the upper right of the moon.

PAUL
Some of our listeners may remember when the United States launched its first space station, Skylab.

RACHEL
The day was May 14th, 1974. Initially, the launch seemed to go well.

PAUL
The outer surface of Skylab acted as a micrometeoroid shield. Engineers designed it to extend a little distance away from the main body of the space station after it entered orbit.

RACHEL
Unfortunately, the shield deployed from the space station during its ascent to orbit.

PAUL
This permitted the rush of the atmosphere to rip it and one of Skylab’s solar arrays off the space station.

RACHEL
Because of the repairs performed by the first crew of astronauts to visit Skylab, the mission of the space station was able to continue.

PAUL
Among their experiments, astronauts made observations of the sun with an array of several telescopes.

RACHEL
Because the Space Shuttle launched several years later than planned, Skylab was not rescued and refurbished before reentering the atmosphere in July 1979.

PAUL
The oldest star cluster easily visible to our eye through binoculars is M-67 in Cancer the Crab.

RACHEL
The stars in this cluster are about four billion years old, or a little younger than our solar system.

PAUL
On the evening of the 16th, the moon is your guide to this cluster.

RACHEL
Use binoculars and search for a hazy spot to the right of the moon.

PAUL
The cluster spans an angle close to the moon’s size.

RACHEL
The heart of Leo the Lion is the star Regulus.

PAUL
It’s the yellowish-orange star above the first quarter moon on the night of the 17th.

RACHEL
While it doesn’t look like much to our eye, Regulus is quite a large star. It has a diameter five times greater than the sun’s and spins much faster.

PAUL
And we mean fast. Regulus rotates once in 16 hours versus the 24 days it takes our sun to rotate once.

RACHEL
Because of its large girth and short rotational period, the surface of Regulus travels at nearly 70,000 miles per hour at its equator.

PAUL
That high speed creates a budge at the equator. The bulge makes Regulus 33% wider across its equator than across its poles.

RACHEL
That’s Idaho Skies for the third week of May. Next week, you can locate Saturn and the star Spica next week with a little help from the moon.

PAUL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Paul…

RACHEL
and Rachel.

PAUL
Dark skies and bright stars.

Transcript for April 28 - May 4

RACHEL
Welcome to Idaho Skies for the first week of May. We’re your hosts, Rachel…

PAUL
… and Paul.

RACHEL
The moon is at third quarter on the 2nd.

PAUL
First and third quarter moons are half moons.

RACHEL
The first quarter is the half moon most people see after sunset in the south.

PAUL
Sunlight illuminates the right half of the moon, or the moon’s eastern hemisphere.

RACHEL
At the third quarter moon, the sun illuminates the moon’s western hemisphere. Unlike the first quarter moon, the third quarter moon doesn’t rise until around midnight.

PAUL
The first and third quarter moons are excellent astronomical objects for binoculars and small telescopes.

RACHEL
That’s because the terminator of the first and third quarter moons point directly towards Earth.

PAUL
As a result, the shadows on the face of the moon are stretched their longest from our perspective.

RACHEL
One thing you will notice about the third quarter moon is that the western hemisphere of the moon is covered in more extensive maria than the eastern hemisphere.

PAUL
The maria are vast lava flows that filled ancient impact basins.

RACHEL
This occurred around 3.9 billion years ago when the moon’s interior was still hot.

PAUL
The flooding occurred in waves so each eruption left a thin layer of lava covering the previous eruption.

RACHEL
When you look at the lunar maria though your binoculars, you’ll see layers of rock older than any rocks on Earth.

PAUL
The moon’s largest impact basin is 1,500 miles across and eight miles deep in places. That’s large enough to span one quarter of the moon.

RACHEL
The impact basin is located between the crater Aitken and the moon’s South Pole.

PAUL
Astronomers named this impact basin the South Pole-Aitken basin and it’s the moon’s oldest recognized impact basin.

RACHEL
Because the impact basin is located at the Moon’s South Pole, we were unaware of its existence until spacecraft began exploring the moon in the early 1960s.

PAUL
It wasn’t until the 1990s that scientists mapped the complete topography of the South Pole-Aitken basin, and discovered that it is one of the solar system’s largest impact basins.

RACHEL
May 3rd is Space Day.

PAUL
Space Day is a celebration of humanity’s exploration of outer space. It is sponsored by the aerospace company Lockheed Martin.

RACHEL
Check out the Space Day website to see if anything is happening near you. www.spaceday.org

PAUL
That’s Idaho Skies for the first week of May. Join us next week to hear about Idaho’s next meteor shower.   

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel…

PAUL
and Paul.

RACHEL
Dark skies and bright stars.