PAUL
Welcome to Idaho Skies for the third week of November. We’re your hosts, Paul...
RACHEL
...and Rachel.
PAUL
We get to see a decent meteor shower on the night of the 17th and morning of the 18th.
RACHEL
It’s the Leonid meteor shower and in dark skies you can expect to see 20 meteors per hour for m this shower.
PAUL
That’s three times as many meteors as you might see on a quiet night.
RACHEL
Better still, this week the moon is a thin crescent.
PAUL
That’s good news because the moon’s feeble light is unable to interfere with the meteor shower.
RACHEL
As you drive to work on the 19th, look for the brightest star beneath the moon.
PAUL
It’s Spica, the brightest star in the constellation of Virgo.
RACHEL
Spica is close to the moon, only twice the moon’s apparent diameter away.
PAUL
Looks can be deceiving however.
RACHEL
While the moon is only 1.5 seconds away at light speed, Spica is 262 years.
PAUL
Here’s your chance to see a very thin crescent moon.
RACHEL
On the 20th at 6:30 AM, the moon is only two days away from being new.
PAUL
That means it appears as a very thin crescent.
RACHEL
Look at the moon through binoculars and you may notice that you can see the rest of the moon, even though its night time on that part of the moon.
PAUL
This is called Earthshine.
RACHEL
Earthshine is caused by the reflection of sunlight off of Earth.
PAUL
Earth is much more reflective to sunlight than is the moon, so it can illuminate the dark portion of the moon well enough for us to make out some lunar surface markings.
RACHEL
Astronomers call the reflectivity of an astronomical body its albedo.
PAUL
And the moon’s albedo is 0.07, or just 7%.
RACHEL
That’s about as dark as fresh asphalt.
PAUL
Earth’s albedo on the other hand is 0.39, or 39%.
RACHEL
If you were an astronaut standing on the moon during the night, you could look up and see Earth shining overhead.
PAUL
Earth would be five times brighter and four times larger than the moon appears to us on Earth.
RACHEL
So its no wonder we can see the effects of Earthshine on the moon.
PAUL
Look for the thin crescent moon very low in the east-southeast.
RACHEL
Not many people have ever observed the moon this close to new.
PAUL
That’s Idaho Skies for the third week of November. Next week go look for the Solitary One, we’ll tell you how to find it.
RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.
For Idaho Skies this is Rachel...
PAUL
...and Paul.
RACHEL
Dark skies and bright stars.
Suggestion: When comparing diameters, use "wider" instead "bigger" to avoid confusion. E.g. "Earth would be...four times larger than the moon appears to us on Earth," could be interpreted as "four times the apparent area." "Earth would be...four times wider than the moon appears to us on Earth" eliminates the ambiguity.
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