Get ready for a 'blue moon'

Last night's full moon is the first of two such events for December. When there are two full moons in a single month, the second one, on Dec. 31, is called a "blue moon."

The name has nothing to do with the color of the moon on that night. It will be the same color it usually is. The reasoning behind such a name is an event that is lost in folklore.

My best guess is that it has something to do with the rarity of the event, you know, like "Once in a Blue Moon."

In Native American lore, the full moon of December is called the "cold moon," having to do with the season of the year and, no doubt, the coldness of the temperatures.

The stars of summer are hanging on by a thread in the early evening in the west. The Summer Triangle of Vega, Deneb, and Altair are plainly visible even in moderately light polluted cities.

The autumnal stars of The Great Square of Pegasus are placed almost directly overhead with the two lines of Andromeda reaching out toward her hero Perseus. Andromeda, looking like a sideways "M" and Cepheus can be found in the northern sky.

By 8 p.m. MST tonight the stars of winter, Gemini, the Twins, Orion, the Hunter, Taurus, the Bull, and Auriga, the Charioteer will be standing above the eastern horizon rising with the full moon.

Here is something fun; after finding Vega, the brightest star in Lyra, the Harp, in the west, turn around and look east where you will find Capella, the brightest star in Auriga, They are both almost the same distance above the horizon.

Now would be a good time to begin planning your Geminid meteor shower watch party. All you will need is a very dark-sky place, a nice reclining lawn chair, a sleeping bag or some blankets, and a nice jug of hot chocolate or coffee.

The Geminids, which seem to radiate from the constellation Gemini, are a nice shower to watch not only because of the high number of zipping streaks of light, but we won't have to wait until the wee hours of the morning to view them.

Gemini clears the eastern horizon and will be in a viewable position by 10:00pm MST on Sunday evening, Dec. 13 and since there will be no interference from the moon, the viewing session should be a good one.

However, if you want to see a really good showing, wait until after midnight on Dec. 14, when the Earth will be in mid-stream for the meteors. A Zenith Hourly Rate (ZNR) of 100 meteors per hour may be possible.

Viewing a meteor shower with a high ZNR is sort of like driving in a snow storm after dark with the headlights on. You know the snowflakes are falling down, but in the headlights they appear to be coming straight at you.

That is why it is better to view meteor showers after midnight. That is when the side of Earth you are standing on is facing directly into the shower stream.

SKY WATCH:

Jupiter is still high in the southwest in the early evening but only for a little while longer. Mars is above the eastern horizon by 10 p.m. MST and will be rising earlier each night. Keep up with your Mars watch and note how much brighter the planet gets week by week. It will be at opposition, or opposite the Sun in our evening sky on Jan. 29. Likewise, Saturn is rising earlier each morning and will be above the eastern horizon at midnight by months end.

NEXT TIME:

More astronomical blathering.