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.
Monday, November 25, 2013
Polaris is our Star for December
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.
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.
Sunday, November 17, 2013
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.
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.
Saturday, November 2, 2013
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.
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
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.
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