Transcript for November 4th, 5th, and 6th

RACHEL
Welcome to Idaho Skies for November 4th, 5th, and 6th. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
The moon travels between Venus and Mars by the 4th.

PAUL
Venus is the brilliant star to the moon’s lower right…

RACHEL
…and Mars is the fainter yellow-orange star to the moon’s upper left.

PAUL
Both Venus and Mars are rocky worlds like Earth.

RACHEL
However, Venus is slightly smaller than Earth…

PAUL
…and Mars is only half the size of Earth.

RACHEL
Those are mild differences compared to the differences in their atmospheres.

PAUL
An atmosphere 90 times denser than Earth’s enshrouds Venus.

RACHEL
Compare this to Mars, which has an atmosphere less than 1/100th as dense as Earth’s.

PAUL
Why the huge difference between two rocky worlds with sizes not all that different?

RACHEL
Good question. We know Mars once has a more substantial atmosphere because of the signs that liquid water once flowed over its surface.

PAUL
Astronomers suspect that the small size of Mars is probably an important factor.

RACHEL
That’s because small planets tend to cool faster than large planets.

PAUL
And planets with cold planetary cores lose their protective magnetic fields.

RACHEL
Without a planet-wide magnetic field, solar wind begins stripping away the planet’s atmosphere.

PAUL
So over time, the atmosphere of Mars went to nearly zero, along with most of the planet’s water.

RACHEL
Except for any water safely frozen below its surface.

PAUL
Which was first seen by the Mars Phoenix lander in 2008.

RACHEL
That’s Idaho Skies for the 4th, 5th, and 6th of November.

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.