THE SKY THIS JANUARY: MOON TAKES CENTER STAGE DURING LUNAR ECLIPSE

What a difference the jet stream can make. During the fall, the jet stream routed weather systems well north of us giving beautiful, clear skies. In December, the jet stream finally moved south to its more seasonal position giving us a cloudy month. It did, however, clear off enough to give us great views of the brighter than normal full Moon.

What helps make astronomy interesting is the combination of unchanging, infinite beauty with rapidly evolving, daily phenomena. The planets dominated this fall, but this month they share the limelight with a close relative. While Jupiter and Saturn are nearly overhead at sunset they have waned some from their full glory. Venus still commands the morning skies but is starting its dive into the Sun being noticeably closer by the end of the month.

What dominates this month is the Moon. After waiting its turn in the shadows, the Moon now takes center stage as North America witnesses one of the best lunar eclipses possible. A lunar eclipse occurs when the Moon travels into the Earth's shadow. The Moon does not travel into Earth's shadow every month because its orbit is tipped with respect to the Earth's and usually misses. But from 10:00 p.m. to 11:30 p.m. (a time when most people are still awake) on the night of the January 20, the Moon travels close to the darkest part of the Earth's shadow.

While direct sunlight is prevented from touching the Moon during an eclipse, sunlight is still bent around by Earth's atmosphere, like a giant lens, giving the Moon various shades of a red color. Depending on the amount of cloud cover over the Earth during the eclipse, we could expect anything from a coal dark Moon to one with a glowing, coppery hue.

If you wish to record the Moon in its glory on film or VCR, you should use as large a telephoto lens as possible since the Moon is but a small dot for normal lenses. One interesting thing you can do with an ordinary lens and a 35 mm camera is multiple exposures on the same negative. Try to point the camera where the full Moon will be at 10:45 p.m. Keep the lens open by using a cable release and starting around 9:45 p.m., take a short exposure every five minutes by uncovering/covering the lens until 11:45. When the film is processed you should see multiple images of the Moon as it dives into the shadow and then re-emerges.

The Big Dipper constellation reappears low in the northeast allowing us to once again easily find the North Star by following the last two stars of the dipper till we find a solitary star, the North Star. Orion dominates the eastern sky being well placed for mid evening viewing.

Notice the color contrast between the hot, blue-white, Rigel and the cool, red, Betelgeuse. This is a classic example of how astronomers can deduce the temperatures of stars by their colors.

The winter Milky Way spans the sky from the northwest to nearly overhead, to the east-southeast. It is fainter than the summer Milky Way as we are looking away from the galactic center towards the infinity of the rest of the Universe and are seeing the last outposts in the disk of our own galaxy.

Dr. Michael L. Cobb is the Chairperson of the Physics Department at Southeast Missouri State University and can be reached at 651-2172.