Transcript: 13 - 19 December

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

PAUL
...and Paul.

RACHEL
The moon passed very close to the sun last week.

PAUL
And now it reappears in the low southwest on the evening of the 13th.

RACHEL
The moon’s not even three days old yet.

PAUL
That means its thin crescent won’t show a lot of lunar detail.

RACHEL
Any craters you do manage to see through your telescope will be those near the bright edge of the moon.

PAUL
Therefore, nearly edge-on which makes them look like narrow ovals.

RACHEL
However, you stand a good chance of seeing Earthshine illuminating the dark portion of the moon.

PAUL
You’ll need to wait until around 6:45 PM on the 13th before the sky becomes dark enough to make Earthshine apparent.

RACHEL
Don’t wait much longer however, as the moon gets too close to the horizon by 7:15.

PAUL
The Geminid meteor shower reaches its peak intensity on the night of the 13th and morning of the 14th.

RACHEL
The Geminids are one of the best meteor showers because of its intensity, or the number of meteors visible per hour.

PAUL
Also because it’s radiant point is above the horizon all night.

RACHEL
The radiant point of a meteor shower is where all the meteors in the shower appear to originate.

PAUL
The position of the radiant is related to where Earth’s orbit intersects the meteor showers orbit.

RACHEL
And to the time of the year that the intersection occurs.

PAUL
In the case of the Geminids, the radiant is located in the low east early at sunset and overhead by 3:00 AM.

RACHEL
This year, the moon is a thin crescent that sets by 8:00 PM.

PAUL
Meaning the rest of the night is undisturbed by moonlight.

RACHEL
In dark skies, and on a clear night, one can expect to see upwards of 60 meteors per hour from this shower.

PAUL
So spend a little time outside on the 13th enjoying the Geminid meteor shower.

RACHEL
The moon passes through the constellation of Capricornus the Sea-Goat on the night of the 14th.

PAUL
The constellation’s brightest star is called Algedi, and it’s located to the moon’s right.

RACHEL
Hey, did you know this star appears in popular fiction?

PAUL
In Frank Herbert’s Dune novels, the name Algedi is the source for the name of the planet Giedi Prime.

RACHEL
Which is home world of the evil Baron Vladimir Harkonnen.

PAUL
The seventh planet is Uranus and its bright enough to be visible to the unaided eye in very dark skies.

RACHEL
And that means it’s visible through binoculars in most other skies.

PAUL
The problem is that the planet doesn’t announce its presence like the brighter planets.

RACHEL
Therefore, it takes something like the moon to help you locate this distant planet.

PAUL
On the evening of the 19th, you’ll find Uranus just above the moon.

RACHEL
To find it, place the moon at the bottom of the field of view of your binoculars.

PAUL
Then look up along the moon’s terminator or boundary between lunar day and night.

RACHEL
Just below the middle of you binoculars is a star that’s actually the planet Uranus.

PAUL
The distance to Uranus is 19 times greater than the distance to the sun.

RACHEL
Therefore, the light you see from Uranus left 2¾ hours ago.

PAUL
That’s Idaho Skies for the third week of December. Next week, winter begins.

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.