Transcript for Febraury 22 to 28

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

RACHEL
...and Rachel.

PAUL
The moon passes close to the Pleiades and Hyades star clusters on the 24th.

RACHEL
These are the two largest and brightest star clusters in the Northern hemisphere.

PAUL
Both clusters and the moon will form an attractive target for your binoculars.

RACHEL
The moon is an excellent target for your telescope.

PAUL
However, extended objects like the Hyades and Pleiades don’t appear anywhere as nice through most telescopes.

RACHEL
That’s because most telescopes have too narrow of a field of view.

PAUL
And their field of view gets more restrictive as their magnification increases.

RACHEL
Wide angle telescopes like rich field telescopes or spotting scopes are designed to provide large fields of view.

PAUL
However, they do this by sacrificing their magnification.

RACHEL
But that’s alright; there are many things in the night sky that are better at low power.

PAUL
The moon just clips the edge of the Hyades star cluster on the 25th.

RACHEL
This will be a perfect sight for your binoculars.

PAUL
Astronomer Kenneth Edgeworth was born 135 years ago on the 26th.

RACHEL
He should be more famous since he predicted a region of comets surrounded the outer reaches of the solar system.

PAUL
We often hear this belt of "comets in waiting" called the Kuiper Belt.

RACHEL
Some people call this region the Kuiper-Edgeworth Belt because Kuiper and Edgeworth made predictions on its existence.

PAUL
However, a careful reading of their arguments reveals that these astronomers didn’t actually predict what astronomers began discovering in 1992.

RACHEL
That’s because when they made their prediction, astronomers believed that Pluto was an Earth-sized object.

PAUL
And as a result, its gravity scattered all the comets in the belt out of the solar system.

RACHEL
However, there are two other astronomers who did make accurate predictions.

PAUL
They’re astronomers Fred Whipple of the United States and Julio Fernandez of Uruguay.

RACHEL
They understood that Pluto couldn’t affect this belt very strongly and that icy bodies still orbit the sun.

PAUL
Pluto is one of the largest Kuiper Belt objects and that there are millions more out there.

RACHEL
However, the largest one that astronomers have discovered doesn’t reside in the Kuiper Belt.

PAUL
What?

RACHEL
Yep, it’s now the largest satellite of Neptune.

PAUL
Oh, you mean Triton.

RACHEL
That’s right. It orbits Neptune in the opposite direction that Neptune spins on its axis.

PAUL
And that’s a dead giveaway that it escaped from the Kuiper Belt and was captured by Neptune.

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

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 Febuary 15th to 21st

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

PAUL
...and Paul.

RACHEL
The moon is new on the 17th.

PAUL
So you should look for Earthshine on the mornings of the 15th and 16th.

RACHEL
And again on the 19th and 20th.

PAUL
Earthshine is sunlight reflected off of the Earth and onto the moon.

RACHEL
Through your binoculars, you’ll see that earthshine faintly illuminates some of the lunar maria on the moon’s dark side.

PAUL
Over 100 years ago, some astronomers hypothesized that a planet existed beyond Neptune, the most distant planet known at the time.

RACHEL
They did because they believed Neptune was not traveling around the sun in a proper orbit.

PAUL
However, it turns out these hypothesizes where based on poor positional data, Neptune actually was traveling around the sun as it should.

RACHEL
One observatory looking for this unknown planet, which they called Planet X, was the Lowell Observatory in Flagstaff, Arizona.

PAUL
They hired Clyde Tombaugh, a Kansas farm boy to photograph regions of the sky at night and then scan the photographic plates during the day.

RACHEL
He was literally looking for a needle in a haystack.

PAUL
That needle was a single faint star that appeared to shift its position relative to millions of fixed stars.

RACHEL
This was very time consuming and Tombaugh required intense concentration and dedication.

PAUL
However it paid off, Tombaugh succeeded in detecting Planet X 85 years ago on the 18th.

RACHEL
His discovery was eventually named Pluto, the Roman god of the underworld.

PAUL
Tombaugh’s planet was tiny, only 1,400 miles across or about 60% the size of the moon.

RACHEL
On average, Pluto is 4.5 billion miles away from the sun or over 45 times farther from the sun that Earth.

PAUL
At that distance, the sun’s gravity is so weak that it takes Pluto 247 years to orbit the sun and its surface temperature is -380 degrees Fahrenheit.

RACHEL
For over 60 years, Pluto was listed as one of the nine planets of the solar system.

PAUL
Late last century, some astronomers argued that Pluto shouldn’t be classified as a planet at all.

RACHEL
Pluto they believed was part of an undiscovered disk of small icy bodies surrounding the outer edge of the solar system.

PAUL
This belt was apparently the home of many of the comets that graced our skies.

RACHEL
It took until 1992, but eventually astronomers began discovering some of these millions of icy bodies.

PAUL
As a result, Pluto got an official demotion.

RACHEL
However, get ready for more news about Pluto and its place in the solar system.

PAUL
That’s because this tiny world will be in the headlines on July 14th.

RACHEL
On that day, the New Horizons spacecraft will visit Pluto during its flyby mission.

PAUL
Much closer to home, look for the young crescent moon on the evening of the 20th.

RACHEL
That evening however, you might first notice much brighter Venus.

PAUL
Just above Venus will be the planet Mars and our moon.

RACHEL
Since the moon will be an incredibly thin crescent, earthshine should be very easy to see once the sky gets dark.

PAUL
If you have a camera, you might want to try taking a few photographs.

RACHEL
That’s Idaho Skies for the third week of February. Many of the comets we see reside inside a belt surrounding the outer edge of the solar system and that’s our topic next week. 

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.

RACHEL
Dark skies and bright stars.

Transcript February 8 - 15

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

RACHEL
...and Rachel.

PAUL
That star you see below the gibbous moon on the morning of the 9th is Spica.

RACHEL
Spica is the brightest star of the constellation of Virgo the Maiden.

PAUL
Virgo is the largest constellation in the Zodiac and the second largest constellation overall.

RACHEL
Unfortunately, Virgo is also a rather dim constellation.

PAUL
So you really need to get away from town in order to make it out.

RACHEL
There are a few double stars that really stand out in binoculars.

PAUL
One of those goes by the name of Zubenelgenubi.

RACHEL
The spacing between the stars of Zubenelgenubi is so wide that some people can see both without optical aid.

PAUL
However, it’s much easier through binoculars.

RACHEL
You can see this double star for yourself on the morning of the 11th.

PAUL
That’s right, look for the brightest star just below the moon.

RACHEL
Looking for Saturn?

PAUL
Well, the ringed world is to the moon’s left on the morning of the 12th. RACHEL You’ll need at least a small telescope or spotting scope in order to see its rings and largest satellite, Titan.

PAUL
Hey, what’s that bright star in the south?

RACHEL
It’s Sirius, the brightest star of Canis Major the Big Dog.

PAUL
Sirius is the brightest star in the heavens and only the planets Venus, Mars, and Jupiter can surpass its nighttime brilliance.

RACHEL
Sirius is a bright white and appears to throw off sparks of color when it’s low to the horizon.

PAUL
That’s because there’s more atmosphere low in the horizon to refract its starlight.

RACHEL
Did you know that Sirius has a strange companion?

PAUL
Even in the early 19th century, astronomers knew there was something odd about its companion.

RACHEL
Astronomers could see that Sirius wobbled back and forth as if a heavy companion star was tugging on it.

PAUL
However, try as they might, no astronomer could detect a star close to Sirius to account for its wobbly motion.

RACHEL
It wasn’t until 1854 that astronomers finally discovered a star orbiting Sirius.

PAUL
We call the companion of Sirius the Pup Star.

RACHEL
It has the mass of the sun, but is nowhere as bright.

PAUL
This means it’s very small, about the size of Earth.

RACHEL
We call these stars white dwarfs.

PAUL
How do white dwarfs form?

RACHEL
Once the nuclear fuel of a star like the sun runs out, the star collapses on itself.

PAUL
It continues collapsing until its electrons are nearly shoulder to shoulder.

RACHEL
The repulsion between electrons keeps white dwarf stars from collapsing any smaller.

PAUL
This extreme collapse makes white dwarf stars incredibly dense.

RACHEL
You bet. A billiard ball of white dwarf weighs as 100 family cars.

PAUL
That’s Idaho Skies for the second week of February. Next week we’ll tell you about the Kansas farm boy who discovered a planet.

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 February 1st to 7th

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

PAUL
...and Paul.

RACHEL
After it gets dark on the 2nd, look for the Beehive star cluster to the moon’s left.

PAUL
The Beehive is among the largest of the star clusters and is located just beyond a binocular’s field of view from the moon.

RACHEL
That means you need to place the moon just outside the right side of your binoculars.

PAUL
Then the star cluster will appear on the very left edge of your field of view.

RACHEL
And the cluster is nice in binoculars and appears three times larger than the moon appears.

PAUL
Did you know you can see this cluster in dark skies, like those found outside of town?

RACHEL
It appears as a faint fuzzy cloud.

PAUL
The ancient Greek astronomer Aratus could see it and named it the Little Mist back in 270 BC.

RACHEL
Hey, what’s that bright star to the left of the moon on the 3rd?

PAUL
It’s not a star, it’s the planet Jupiter.

RACHEL
You should notice that Jupiter has a slightly off-white tint.

PAUL
And that it will resist twinkling unlike its surrounding stars.

RACHEL
Jupiter is even larger and brighter this week than on average.

PAUL
Why is that?

RACHEL
That’s because Jupiter reaches opposition on the 6th.

PAUL
Oh, that’s when Jupiter is located opposite the sun in our sky.

RACHEL
That’s right and it means that Jupiter is its closest to Earth.

PAUL
So as a consequence, Jupiter is larger and brighter than average.

RACHEL
If you have any sort of optical aid, even a pair of binoculars, then aim it at Jupiter.

PAUL
You’ll see two stars forming a straight line with Jupiter, and Jupiter in the middle.

RACHEL
In your binoculars, the bottom star is Callisto and the top star is Ganymede.

PAUL
Ganymede is the largest satellite in the solar system.

RACHEL
Would you be surprised to hear that it’s even larger than the planet Mercury?

PAUL
That’s right; our solar system has a moon that’s larger than a planet.

RACHEL
The yellowish star to the moon’s left on the 4th is Regulus.

PAUL
Regulus is the brightest star of Leo and Lion and it represents the lion’s heart.

RACHEL
The star forms the bottom of a backwards question mark of six stars.

PAUL
You should be able to see these stars as long as you’re not in downtown Boise.

RACHEL
The question mark pattern of stars above Regulus represents the back of Leo’s head and his mane.

PAUL
The rest of Leo is a triangle of three stars located a short distance to the east.

RACHEL
Star maps illustrate Leo setting like the Great Sphinx of Egypt.

PAUL
That’s Idaho Skies for the first week of February. Next week we’ll talk about the brightest star in the sky.

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.

February's Star is Sirius

This month look for the star Sirius. Sirius is the lucida of the constellation of Canis Major, the Big Dog and its half way up in the sky when you face towards the southwest during February nights. It’s the brightest star in the heavens and only the planets Venus, Mars, and Jupiter can surpass its nighttime brilliance. Sirius is a bright white star that appears to throw off sparks of color when it’s low to the horizon. That’s because there’s more atmosphere low in the horizon to refract its starlight. If you were born in 2006, then Sirius is your birthday star this year because the light you see tonight left Sirius 9 years ago. The name Sirius comes from the Greek word for scorching. During the Dog Days of summer, which occurs in early August, the sun and Sirius are close together in the sky. The Greeks believed that the heat of Sirius added to the sun’s heat, making these days especially hot.  

Sirius has a strange companion. Back in the early 19th century, astronomers discovered that the star wobbled back and forth as it slowly drifted across the sky. It was as if the gravity of a massive star was tugging on it. However, try as they might, no astronomer could discover a star close to Sirius to account for its wobbly motion. It wasn’t until 1854 when Alvan Clark turned a new 18 inch refracting telescope to the star that he discovered a tiny spark of a star next to Sirius. The star was not really that faint, but its closeness to Sirius made it impossible to see with previously telescopes.

The companion to Sirius, called the Pup Star, orbits Sirius with a period of fifty years. From the amount of tugging Sirius experiences from this star, we know that the Pup Star has a mass equal to our sun. What’s so surprising is that if we viewed the sun from nine light years away, we would easily see it with the unaided eye. However, the Pup Star isn’t. What gives?  Stars like the Pup Star have the spectrum of a very hot star. Therefore, every square foot of these stars is more intense than an equal area of our sun. The low total brightness but high surface intensity of these types of star tells astronomers that they must be very tiny, about the size of our planet. We call them White Dwarf stars.

Once each white dwarf was like our sun, moderately bright and moderately large. Once its nuclear fuel ran out, the star collapsed on itself because it could no longer support its weight using nuclear fusion. Only the repulsion between electrons keeps white dwarf stars from collapsing any smaller. The compression of a star into a white dwarf makes it incredibly dense. A billiard ball of white dwarf weighs as much as a tank, or about the same weight as 100 family cars.