Transcript: 28 February - 6 March 2006

PAUL

Welcome to Idaho Skies on Radio Boise. This is the first week of March. We’re your hosts, Paul...

RACHEL

...Rachel..

KRIS

...And Kris

PAUL

The planet Mars remains close to the Hyades for the first half of this month.

KRIS

The Hyades is a galactic star cluster. And it represents the face of the bull, Taurus.

KRIS

There are two kinds of star clusters in our galaxy, galactic and globular. Galactic clusters are loose groupings of stars while globular clusters are tightly packed spheres.

PAUL

The dozens to hundreds of stars of a galactic star cluster condensed from a single cloud of dust and gas.

KRIS

But the density of stars inside a galactic star cluster is far too low for their mutual gravity to hold the cluster together. So over time the random motions of the stars cause the galactic star cluster to fall apart.

KRIS

On the other hand, the stars in a globular star cluster are densely packed. And their mutual gravity prevents most of them from escaping.

KRIS

The stars in a galactic star cluster tend to be young, in star years. The Hyades star cluster formed some 400 million years ago.

PAUL

That’s about when plants began to colonize the land.

KRIS

Look for Mars tonight and you’ll find our second closest galactic star cluster, the Hyades.

KRIS

Mars is the orange colored star half way up in the southwest at nine PM. On most nights Mars will not twinkle like the other stars.

KRIS

The orange star to the left, or east of Mars is a real star. It’s called Aldebaran, but astronomers know the star as Alpha Tauri.

KRIS

The star is named Aldebaran, and not Alderan, princess Leia’s home world. Aldebaran is well within our galaxy at a distance of 65 light years.

KRIS

If you’re 65 this year, then the light of Aldebaran you see tonight left the star the same year you were born. This makes Aldebaran your birthday star this year.

KRIS

Aldebaran appears at the tip of the Hyades star cluster. But actually Aldebaran is less than half the distance away.

PAUL

This is a good example how chance alignments can make widely spaced stars look like neighbors.

KRIS

Your best view of the Hyades star cluster is with a common pair of field binoculars.

KRIS

With the unaided eye you’ll only see about a dozen stars in the Hyades star cluster.

KRIS

But through binoculars you’ll see dozens of stars forming a V shape. The cluster will fill the binocular’s field of view with stars.

PAUL

But beware when you observe the Hyades.

KRIS

For according to H. P. Lovecraft, the Old Ones currently reside on a star near Aldebaran.

PAUSE

PAUL

Forty years ago on the first of March a spacecraft successfully landed on another planet for the first time.

KRIS

The planet was Venus and the spacecraft was Venera 3. The Soviet Union launched Venera 3 during its space race with the United States.

KRIS

Venera 3 was their eighth attempt to reach Venus, our closest neighbor in the solar system.

KRIS

Soviet built spacecraft tended to be poorer in quality than US spacecraft. Because of this, the radio onboard the Venera 3 spacecraft failed before it landed on Venus.

PAUL

But the silent Venera 3 did carry something else to Venus, medallions.

KRIS

Today the medallions are probably corroding away in the harsh atmosphere of Venus.

KRIS

You can see Venus if you look low in the southeast shortly before sunrise. Venus appears as the brightest star in the sky.

KRIS

That’s Idaho Skies for the first week of March. Join us next week to hear about lunar maria and Ivan Ivanovich. For Idaho Skies this is Rachel.

KRIS

...Kris...

PAUL

... and Paul.

Transcript: 21 - 27 February, 2006

PAUL Welcome to Idaho Skies on Radio Boise. This is the second week of February. We’re your hosts, Paul..

RACHEL ...Rachel..

KRIS ...And Kris

PAUL This week the inner planet Mercury makes its appearance.

KRIS Last week Idaho Skies told you the path that the planets travel around the sun is low to the horizon on February mornings. Well, the opposite is true in the evening.

RACHEL The ecliptic rises steeply in the evening, which means planets in the west after sunset are much higher above the horizon.

KRIS Mercury is at its best this week. But that doesn't mean Mercury is as easy to see as Venus.

RACHEL Mercury orbits the sun at a distance of 36 million miles to the earth's distance of 93 million miles. Therefore Mercury never appears very far from the sun.

KRIS But you can find Mercury if you look low in the west at seven PM, or 30 minutes after sunset. Mercury will be the first star you can see.

PAUL And by low, we mean low. Mercury will only be nine degrees above the horizon.

RACHEL Nine degrees is about the angle your four fingers span when your arm is fully outstretched. So you'll need a clear western horizon to see Mercury.

PAUL Mercury is getting a visitor in 2011

KRIS The Messenger spacecraft is on its way to this mysterious planet.

RACHEL Mercury has only been visited by one spacecraft, the Mariner 10.

KRIS The Mariner 10 spacecraft discovered that Mercury looks a lot like the moon, with craters, impact basins, and smooth plains.

PAUL Since it's so close to the massive sun, Mercury's rotation is tidally locked to the sun.

RACHEL This means the planet rotates on its axis in sync with its revolutions around the sun.

KRIS For every orbit around the sun, Mercury only rotates one and a half times on its axis.

RACHEL If this were true on Earth, our days would last eight months. And with a day lasting eight months, a year would be a day and a half long.

KRIS The surface of Mercury is extremely hot. Day time temperatures can soar to a high of 870 degrees Fahrenheit.

PAUL That's hot enough to melt lead.

RACHEL But Mercury is not the hottest planet in the solar system. Because of its dense atmosphere, Venus has a slightly hotter surface temperature of 900 degrees.

PAUL Mariner 10 only photographed half of Mercury during its three passes of the planet in 1974 and 1975.

RACHEL To photograph Mercury, Mariner 10 was put into an orbit similar to Mercury

KRIS Since Mercury rotates in sync with its orbit, every time Mariner 10 passed Mercury, the same side of Mercury was facing the sun, so there was only one side we were able to see.

RACHEL The largest feature on Mercury recorded by Mariner 10 was the Caloris Basin. A huge impact site on the planet measuring 830 miles across. That's larger than Idaho, Washington, and Oregon combined.

KRIS In 2011 the Messenger spacecraft will go into orbit around Mercury, something Mariner 10 was unable to do. So who knows what kinds of features we'll discover on Mercury.

RACHEL That's Idaho Skies for the fourth week of February. Join us next month and hear about the astronomical events visible from Idaho. For Idaho Skies this is Rachel.

KRIS ...Kris..

PAUL ... and Paul.