Idaho Skies Transcript for October 17th and 18th

PAUL
Welcome to Idaho Skies for October 17th and 18th. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
It’s now winter for the Northern Hemisphere of Mars.

And you can find this planet quite easily.

RACHEL
You’re guaranteed to find this planet by following the moon’s lead on the 18th. That orangish star you’ll see to the right of the moon is the Red Planet. Now Mars is a tiny planet with a diameter only half the diameter of Earth. And its small size means gravity is only 38% as strong as it is on Earth.

PAUL
The moon is only half as large as Mars. And its surface gravity is just under half as strong its is on Mars. Now both the moon and Mars are rocky world. But while the moon is gray, Mars is a light orange.

RACHEL
Which is a little unexpected, since the rocks on the moon and Mars are similar. But since Mars has an atmosphere, the iron in its surface is rusted. And that’s similar to what we find on Earth, rusty soil after a long exposure to the atmosphere. This might be an important observation to make on the exoplanets that telescopes are discovering.

PAUL
Because if the exoplanet appears to be more gray than orange, we’ll know it’s more likely a terrestrial planet with no oxygen. But watch out, just because its surface is rusty, doesn’t mean the planet can support life. Because the atmosphere of Mars is a little less than 1% as dense as Earth’s. Much of the Martian atmosphere was lost to space. And what oxygen remains is locked up in rust.

RACHEL
Astronomers discovered that Mars has lost much of its atmosphere due to solar wind. Since Mars is so small, its core cooled quickly and can no longer generate a planet-wide magnetic field. And that lack of large magnetic field has allowed the sun to blow away much of the early Martian atmosphere.

PAUL
Today the rate of lose is only ¼ of a pound of atmosphere per second. But four billion years ago, the sun’s solar wind was much stronger. And it carried away over 99% of the Martian atmosphere in a geologically short period of time. Adios Martian lifeforms.

RACHEL
That’s Idaho Skies for the 17th and 18th of October.

PAUL
Be sure to follow us on Twitter @IdahoSkies for this week’s event reminders and sky maps.

For Idaho Skies this is Paul…

RACHEL
…and Rachel.

PAUL
Dark skies and bright stars.