Transcript for September 13 - 19

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

PAUL
...and Paul.

RACHEL
The moon reappears in the evening sky by the 16th.

PAUL
On that evening and on the 17th, be sure to look for Earthshine.

RACHEL
It’s visible to the unaided eye if the sky is dark.

PAUL
But it’s easier to see through your binoculars.

RACHEL
After detecting the presence of Earthshine, try looking for details on the dark side of the moon.

PAUL
You won’t see craters like you do on the sunlit portion of the moon, but you should be able to see some of the larger lunar maria.

RACHEL
Maria is plural and Latin for sea, as in ocean.

PAUL
The singular form is mare.

RACHEL
Lunar maria are ancient basaltic flood plains, or frozen oceans of lava.

PAUL
They started forming about 3.8 billion years ago after some of the giant building blocks of the planets pummeled the moon.

RACHEL
Astronomers call this time of frequent and massive impacts the Late Heavy Bombardment.

PAUL
The very large craters or impact basins created in the collisions were hundreds of miles across in some cases.

RACHEL
After hundreds of millions of years, lava started welling up from the cracks inside the impact basins.

PAUL
The lava gradually filled the impact basins in sheets of lava miles thick in some cases.

RACHEL
Since the lavas are rich in iron, they tend to be darker than the brighter lunar highlands.

PAUL
That’s because the highlands are rich in a mineral called anorthosite, which is a mineral rich in white-colored feldspar.

RACHEL
The anorthosite is the scum that floated to the top of the once molten moon.

PAUL
Saturn and the moon are very close to each other on the night of the 18th.

RACHEL
Look in the low southwest after dark and you’ll see Saturn only two degrees away from the southern cusp of the moon.

PAUL
That close together means you can see both at the same time in binoculars.

RACHEL
Your binoculars will show some craters in the southern half of the moon.

PAUL
However, they will not show the rings of Saturn.

RACHEL
It takes a magnification of at least 20 power to see the rings.

PAUL
That means a very large and heavy pair of binoculars.

RACHEL
Or better yet, a spotting scope or small telescope.

PAUL
In a small telescope, Saturn appears a distinct yellow in color.

RACHEL
Through a spotting scope, you’ll see Saturn’s largest satellite Titan as a star to the upper right of Saturn.

PAUL
In an astronomical telescope, which inverts images, Titan will appear as the star to the lower left of Saturn.

RACHEL
That’s Idaho Skies for the third week of September. Summer ends next week and we’ll discuss its passing, so be sure to listen in.

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.