Idaho Skies Transcript for December 25th and 26th

RACHEL
Welcome to Idaho Skies for December 25th and 26th. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
The moon reaches first quarter phase on the 26th.

PAUL
This is the most excellent phase for going moon watching.

RACHEL
So listeners who got a new telescope or binoculars for Christmas have the perfect target tonight.

PAUL
Start by placing a low power eyepiece in your telescope.

RACHEL
The low power eyepiece is the one with the largest number written on its side of its barrel.

PAUL
That number is the focal length of the eyepiece in millimeters.

RACHEL
To calculate the magnification of your telescope, divide the focal length of the main lens, or objective by the focal length of the eyepiece you selected.

PAUL
A lower power is usually better than a higher power, especially when trying to locate objects.

RACHEL
Anther reason is that high magnifications also magnify the distortion caused by the turbulent air.

PAUL
When you look at the moon in low power, you’ll notice that the terminator or boundary between day and night runs straight up and down the center of the moon.

RACHEL
You’ll also notice that the southern hemisphere of the moon is packed full of craters.

PAUL
Whether the moon’s southern hemisphere appears at the top or bottom of the moon depends on what kind of instrument you’re looking through.

RACHEL
Binoculars and spotting scopes don’t invert their images, so the southern hemisphere will appear at the bottom of the moon.

PAUL
Telescopes on the other hand do invert their images.

RACHEL
But this is not bad, as binoculars and spotting scopes use additional lens to un-invert their images.

PAUL
Meaning there’s more dimming of the moon’s light and a slight reduction in optical clarity.

RACHEL
Besides, one can always reverse the image of their telescope by standing with their back towards the moon before looking through the eyepiece.

PAUL
That’s Idaho Skies for the 25th and 26th of December.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com

For Idaho Skies this is Paul...

PAUL
...and Rachel.

RACHEL
Dark skies and bright stars.