Transcript for May 22nd to 28th

PAUL
Welcome to Idaho Skies for the fourth week of May. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
Mars reaches opposition on the 22nd.

RACHEL
At opposition, superior planets…

PAUL
…or those beyond Earth…

RACHEL
…are at their closest to Earth for the year.

PAUL
Opposition occurs when the faster orbital motion of Earth results in it catching up to and passing the superior planet in question.

RACHEL
In the process of reaching opposition, superior planets appear to retrograde, or move slightly backwards across the stars.

PAUL
Retrograde motion is an illusion however.

RACHEL
It’s caused by the changing perspective between Earth and superior planets when compared to the fixed stars.

PAUL
Hundreds of years ago…

RACHEL
…that’s when the geocentric or Earth-centered solar system was in vogue…

PAUL
…astronomers and philosophers believed the superior planets actually moved backwards during a short period of time at retrograde.

RACHEL
This was possible because astronomers believed these planets orbited Earth in a set of nested orbits of various sizes.

PAUL
In the 16th century, Copernicus convinced astronomers otherwise.

RACHEL
He explained that retrograde motion was easier to understand when you move the sun to the center of the solar system and demoted Earth to a planet orbiting the sun.

PAUL
In time, other astronomers accepted this explanation, especially after the work of Johannes Kepler in the 17th century.

RACHEL
The bright yellowish star visible to the right of the moon on the 22nd is Saturn.

PAUL
You’ll need at a spotting scope or telescope capable of magnifying at least 25 times in order to see the planet’s rings.

RACHEL
And its largest satellite, Titan.

PAUL
Titan is a fascinating world.

RACHEL
Yes it is. It’s larger than Earth’s moon and cloaked in an atmosphere denser than Earth’s.

PAUL
Unfortunately, it’s also intensely cold on Titan.

RACHEL
How cold?

PAUL
So cold that methane, a gas used to heat our homes, is a liquid.

RACHEL
So cold that its nitrogen-rich atmosphere is almost cold enough to liquefy.

PAUL
Because of its dense atmosphere, Titan has weather.

RACHEL
However, its dense atmosphere prevents it weather from being as dynamic as Earth’s weather

PAUL
Still, this still allows it to rain on Titan.

RACHEL
On Titan, it’s a methane rain falling on rock hard pebbles of water ice.

PAUL
In 2005, the Huygens probe landed on Titan and returned images for 90 minutes.

RACHEL
Those images showed a landscape not too unlike Earth.

PAUL
Including mountains eroded by falling methane rain

RACHEL
And a stream bed where once a liquid methane stream once flowed.

PAUL
That’s Idaho Skies for the fourth week of May. We have a challenge for you next week, to see Neptune in your binoculars.

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.