Saturday, December 4, 2004

Geminid meteor showers will be easy to view Dec. 13-14

Jon Spargo New Mexico Tech Astronomy Club

Dedicated planet watchers will have to rise early this month to see most of the planets now visible to us here on Earth. The magic time will be between one and two hours before sunrise.

Still brightest of all, with 89 percent of its clouded ball illuminated, Venus will be the easiest to find. In early December, Mars will climb up past Venus passing 1-1/2 degrees south of the bright planet on the 5th. Telescopes will show Mars to be a small dot about 1/3 the apparent size of Venus.

Beginning on the 20th, Mercury joins the early morning show reaching greatest elongation on the 29th. On that day, it will also pass 1-1/4 degrees from Venus.

Jupiter rises around 2:30 in the morning as the month begins and will rise around midnight at month's end. Early risers will find Jupiter high in the sky and a good stable target for viewing with a telescope.

Saturn rises around 8 p.m. at the beginning of the month and just after dusk by the end of December. These days Saturn is easy to locate as it is still near the constellation of Gemini. The two bright stars Castor and Pollux are outshone by Saturn but can be easily used to locate the ringed planet.

Speaking of Castor and Pollux, it is often hard to remember which is which. Castor is the dimmer of the two and rises first. These "twins" are quite remarkable in their differences.

At a distance of 34 light years, Pollux is a cool orange giant. Castor, at 52 light years, is actually a sextuple, or a double-double-double! A small telescope reveals two bright stars only a couple of arc seconds apart. A spectrograph reveals that both of these are doubles! About an arc minute to the south lies a dim, ninth magnitude third companion, which is actually a pair of dwarf stars. A planet orbiting around one of these six stars would have some pretty spectacular sunrises and sunsets!

Winter arrives on the 21st at 5:42 p.m. MST when the Sun is furthest south in declination. The Moon is last quarter on the 4th, new on the 11th, first quarter on the 18th and full on the 26th. Santa should be easy to spot while making his rounds in the bright moonlight this year!

On the night of the 13th and early morning of the 14th, there will be no bright moon, which should make for good viewing of the Geminid meteor shower. Appearing to originate from a point near Castor, these slow, bright, yellowish meteors may reach a peak of 75 per hour. Bundle up!

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