Sunday, November 23, 2014

Polaris, the star for December

This month look for the star Polaris, the lucida (brightest star) of Ursa Minor the Little Bear. Polaris is also known as Alpha Ursae Minoris, The North Star, The Pole Star, and The Lode Star. Polaris is the guide to true north (as opposed to magnetic north) so it appears nearly straight up to anyone standing on the North Pole. Polaris is not the brightest star in the sky nor is it exactly true north. Polaris is actually 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. Polaris is the star marking the end of the Little Dipper’s handle.

Polaris is a bit hotter than our sun and older. It’s at the point in its life where it is fusing helium in its core and fusing hydrogen in a shell above its core. This makes Polaris slightly unstable and its outer layers pulsate in size and slightly in brightest. At 430 light years away, you’re seeing light from Polaris that was emitted in the year 1584.

Polaris is an easy star to find since most people can locate the Big Dipper in the sky. The two stars at the end of the Big Dipper’s bowl are called the Pointers and a line drawn up from the Pointers just about runs into Polaris.

Idaho Skies Transcript for November 23rd to 29th

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

PAUL
...and Paul.

RACHEL
On the evening of the 24th, you have a second chance to see a very thin moon this month.

PAUL
This time however, it’s an evening event.

RACHEL
The moon is three days old on the 24th, so it will still be crescent shaped.

PAUL
So look for the moon low in the southwest just after it gets dark.

RACHEL
And don’t forget to use a pair of binoculars so you can see Earthshine.

PAUL
In Earthshine, you should faintly see the lunar seas as dark patches, but you won’t be able to see lunar craters.

RACHEL
The moon passes next to Mars on the evening of the 25th.

PAUL
Look in the low southwest after dark for the brightest star to the moon’s left.

RACHEL
Mars will appear as a star with a decidedly yellowish tint.

PAUL
The Solitary One gets some company on the 29th.

RACHEL
The Solitary One is Fomalhaut, the brightest star beneath the moon that night.

PAUL
Fomalhaut is the brightest star in the constellation of Pisces Austrinus, or the Southern Fish.

RACHEL
The Southern Fish is a faint constellation, just like Pisces above it.

PAUL
At 25 light years away, Fomalhaut is one of the closest stars to our solar system.

RACHEL
But don’t make plans to visit it in search of new life and civilizations.

PAUL
That’s because Fomalhaut is much younger than the sun.

RACHEL
It’s so young that Fomalhaut is still in the process of forming its planets.

PAUL
Within the disk of dust and gas surrounding the star, the Hubble Space Telescope has observed a pin point of light over several years.

RACHEL
That pin point is star light reflecting off a young planet orbiting the outer reaches of Fomalhaut’s disk of dust and gas.

PAUL
The ancients named Fomalhaut the Solitary One because of its location in the sky.

RACHEL
The southern autumn sky around Pisces Austrinus contains mostly large sea-based constellations.

PAUL
And these constellations contain mostly faint stars.

RACHEL
This really lets Fomalhaut stand out.

PAUL
So go outside after dark on the 29th and get acquainted with the Solitary One.

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

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.

Monday, November 17, 2014

Transcript for Nov 16 - 22

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

RACHEL
...and Rachel.

PAUL
We get to see a decent meteor shower on the night of the 17th and morning of the 18th.

RACHEL
It’s the Leonid meteor shower and in dark skies you can expect to see 20 meteors per hour for m this shower.

PAUL
That’s three times as many meteors as you might see on a quiet night.

RACHEL
Better still, this week the moon is a thin crescent.

PAUL
That’s good news because the moon’s feeble light is unable to interfere with the meteor shower.

RACHEL
As you drive to work on the 19th, look for the brightest star beneath the moon.

PAUL
It’s Spica, the brightest star in the constellation of Virgo.

RACHEL
Spica is close to the moon, only twice the moon’s apparent diameter away.

PAUL
Looks can be deceiving however.

RACHEL
While the moon is only 1.5 seconds away at light speed, Spica is 262 years.

PAUL
Here’s your chance to see a very thin crescent moon.

RACHEL
On the 20th at 6:30 AM, the moon is only two days away from being new.

PAUL
That means it appears as a very thin crescent.

RACHEL
Look at the moon through binoculars and you may notice that you can see the rest of the moon, even though its night time on that part of the moon.

PAUL
This is called Earthshine.

RACHEL
Earthshine is caused by the reflection of sunlight off of Earth.

PAUL
Earth is much more reflective to sunlight than is the moon, so it can illuminate the dark portion of the moon well enough for us to make out some lunar surface markings.

RACHEL
Astronomers call the reflectivity of an astronomical body its albedo.

PAUL
And the moon’s albedo is 0.07, or just 7%.

RACHEL
That’s about as dark as fresh asphalt.

PAUL
Earth’s albedo on the other hand is 0.39, or 39%.

RACHEL
If you were an astronaut standing on the moon during the night, you could look up and see Earth shining overhead.

PAUL
Earth would be five times brighter and four times larger than the moon appears to us on Earth.

RACHEL
So its no wonder we can see the effects of Earthshine on the moon.

PAUL
Look for the thin crescent moon very low in the east-southeast.

RACHEL
Not many people have ever observed the moon this close to new.

PAUL
That’s Idaho Skies for the third week of November. Next week go look for the Solitary One, we’ll tell you how to find it.

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 Nov 9 - 15

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

PAUL
...and Paul.

RACHEL
The moon will help you locate Orion the Hunter on the 9th.

PAUL
The majority of the constellation is the tall rectangle located below and right of the moon.

RACHEL
Above the rectangle of Orion is his raised arm and club.

PAUL
This is where the moon is located on the 9th.

RACHEL
So it looks like Orion is about to bat the moon with his club.

PAUL
Be sure to look for the row of three stars located inside the rectangle of Orion.

RACHEL
That’s Orion’s Belt.

PAUL
If you have a pair of binoculars handy, then scan downward from the middle star in Orion’s Belt.

RACHEL
The stars represent his sword, but you’ll notice the second star looks a little fuzzy.

PAUL
That fuzzy spot is located 1,300 light years away.

RACHEL
And it’s not a star, it’s a seething cauldron of star formation called the Orion Nebula.

PAUL
Astronomers have counted at least 700 stars in the process of forming within the Orion Nebula.

RACHEL
Here’s an easy way to identify Gemini the Twins; look for the moon on the night of the 10th.

PAUL
You’ll need to go outside after 10 PM to locate it, however.

RACHEL
Look right above the moon for two horizontal rows of stars.

PAUL
The brightest stars of the constellation, which are located to the left side of the moon, are called Castor and Pollux.

RACHEL
They represent the heads of the twins.

PAUL
Pollux is the brighter of the two stars and nearer the horizon.

RACHEL
Look for a bright star to the moon’s lower right on the 11th.

PAUL
It’s Procyon, the brightest star of Canis Minor, or the Little Dog.

RACHEL
The name Procyon means "Before the Dog".

PAUL
It got this name because it rises shortly before the Dog Star, Sirius.

RACHEL
Procyon appears bright in our sky not because it is a truly bright star, but because it’s so close to Earth.

PAUL
It’s just under 12 light years away for our solar system.

RACHEL
So if you know someone born in 2002, then Procyon is their birthday star this year.

PAUL
Get your binoculars out on the morning of the 13th.

RACHEL
That’s because you’ll be able to find and see the Beehive star cluster.

PAUL
After 3:00 AM, aim your binoculars at the moon and follow it's terminator straight north.

RACHEL
The terminator is the boundary between day and night on the moon.

PAUL
If you put the moon at the bottom edge of your binocular’s field of view, then the star cluster will be located near the center of your binoculars.

RACHEL
In your binoculars, and in dark skies, you should observe at least two dozen stars in the star cluster.

PAUL
That’s Idaho Skies for the second week of November. Next week a fine meteor shower gives us a show. 

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.

Friday, October 31, 2014

This month look for the star Caph in the constellation Cassiopeia. Caph is called Beta Cassiopeiae by astronomers. And as you would guess from its name, Caph is the second brightest star in the constellation.

Cassiopeia may have originated as the Greek goddess, Hecate, but was later transformed into the queen of Ethiopia. According to the Greek legend, Cassiopeia boasted she was more beautiful than the Nereids. The unhappy Nereids complained about this slight to their father, the god of the sea. As punishment, Poseidon sent the sea monster Cetus to destroy Cassiopeia’s coastlands. King Cepheus and queen Cassiopeia learned they could halt the destruction of their lands only if they offered their daughter, Andromeda to the sea monster. So unfortunate Andromeda was chained to the rocks to await the next arrival of Cetus. Fortunately, before the sea monster arrived, Perseus, who was traveling back home on his flying sandals, saw and rescued Andromeda.  

The star Caph is 54 light years away. Therefore, if you were born in 1960, Caph is your birthday star this year. The surface of Caph is 1,600 degrees Fahrenheit hotter than our sun. It’s also four times larger and 28 times brighter. Caph is old enough that the energy from hydrogen fusion can’t preventing its core from contracting. The core is shrinking as a result and growing hotter. Eventually the contraction will warm the core up to the point that helium fusion will begin. Once its helium begins to "burn", Caph will expand in size and change into a cooler giant star.

Transcript for November 2 - 8

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

RACHEL
...and Rachel.

PAUL
The Taurid meteor shower peaks on the morning of the 3rd.

RACHEL
Meteor showers occur when Earth’s orbit intersects the orbit of a comet.

PAUL
The dust ejected from a comet continues to orbit the sun until it slams into Earth’s atmosphere, at speeds ranging from 7 to 70 miles per second.

RACHEL
At a speed of 70 miles per second, a cometary dust particle could cross Idaho from west to east in about six seconds.

PAUL
The hyper-velocity of a reentering dust particle violently compresses the air ahead of it.

RACHEL
This creates a shock wave that heats the air to thousands of degrees.

PAUL
The hot shock wave ahead roasts and melts the reentering dust particle.

RACHEL
Most meteors are vaporizing about 70 miles above Earth’s surface.

PAUL
And most are no larger than a grain of sand.

RACHEL
Unfortunately, for the Taurid meteor shower this year the moon is in a waxing gibbous phase.

PAUL
That means the moon is a nearly full and won’t set until 3:30 AM.

RACHEL
So if you want to observe this shower, you’ll need to wait until after 3:30, when the moon has finally set.

PAUL
By that time, meteors from this shower will appear to originate from overhead.

RACHEL
The Taurids don’t sound like a very promising meteor shower when you consider that you might only see five meteors per hour from this shower.

PAUL
However, the Taurids have several tricks up their sleeve.

RACHEL
Yep. First, the stream of meteoroids forming this shower is massive and spread out.

PAUL
So you can observe meteors from this stream for several weeks around the day of peak intensity.

RACHEL
And second, the rocky material making up the meteoroids tend to be larger, even pebble size.

PAUL
Therefore, Taurid meteoroids can create very bright meteors over several weeks as they reenter Earth’s atmosphere.

RACHEL
The moon appears around two large galactic star clusters on the evening of the 7th and 8th.

PAUL
After it gets dark on the 7th, sweep the region above and below the moon with your binoculars.

RACHEL
You’ll see the Pleiades star cluster above the moon and the Hyades star clusters below.

PAUL
If you miss them or the weather is bad on the 7th, the star clusters will be located above the moon on the 8th.

RACHEL
That’s Idaho Skies for the first week of November. Next week we’ll tell you how to find and observe the Orion Nebula.

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.

Monday, June 30, 2014

Idaho Skies Transacript for July 27 - Aug 2

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

RACHEL
...and Rachel.

PAUL
Like the vast majority of orbits in our solar system, the moon’s orbit around Earth is not a perfect circle.

RACHEL
Closed orbits that are not perfect circles are called elliptical.

PAUL
You can think of them as perfect ovals, but not like an egg.

RACHEL
At its closest to Earth, the distance between the center of the moon and the center of Earth is 225,291 miles.

PAUL
At its greatest distance, the moon is 26,619 miles father away.

RACHEL
Perigee is the term for the closest distance and apogee is the term for the greatest distance.

PAUL
Due to its gravitation interaction with the sun, the distances of lunar apogee and perigee varies from month to month.

RACHEL
On the 28th, the apogee of the moon’s orbit is its greatest for the entire year, about 700 miles farther away than usual.

PAUL
At its greatest distance, it would take you over 9 ½ years to walk to the moon.

RACHEL
On July 30, 1610, Galileo became the first astronomer to observe Saturn’s rings through a telescope.

PAUL
Unfortunately, Galileo’s 20-power telescope was not good enough to show the true nature of the rings.

RACHEL
He thought he was seeing handles on opposite sides of Saturn.

PAUL
Later on, he thought he was seeing two very large satellites.

RACHEL
Things got more confusing for Galileo when two years later, when these objects disappeared altogether.

PAUL
It took decades before Cassini finally figured out that astronomers were seeing rings around Saturn.

RACHEL
Fortunately, you can see Saturn’s rings tonight though a small telescope or even spotting scope and you won’t suffer the confusion Galileo did.

PAUL
The Southern Delta Aquarid meteor shower peaks on the night of the 29th and morning of the 30th.

RACHEL
It’s a pretty good meteor shower and you can expect to see up to 20 meteors per hour in dark skies.

PAUL
Better still, the moon is young and it sets before midnight.

RACHEL
So its light won’t interfere with watching the fainter meteors.

PAUL
Adding to the number of meteors is the fact that July and August contain many overlapping meteor showers.

RAHCEL Any Southern Delta Aquarids will appear to originate from the southeast.

PAUL
So dress warmly and enjoy a shower, meteor shower that is.

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

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.