Everything you always wanted to know about astronomy

Bruce Dennis is a retired scence teacher from Haverling High School.

December starts by permitting Venus to shine just above the Western horizon, exactly where the Sun set an hour ago. A few hours later, Jupiter will rise (in the East) and be up the entire night. On December 10th, Mars, Jupiter, and Mercury will join in a tight group at dawn. This gathering is the most exciting planetary show of the month. Don't miss this one! It'll be 23 years until this happens again. But first, let me invite you to a global star party with expert guides: go to SLOOH.COM and receive images of galaxies, nebulae, and planets live from a telescope in the Canary Islands. You will receive seven nights free and $4.95 after that. This is brought to you by the Astrophysics Institute of the Canary Islands and is on-line every night.

Venus sets about a half hour after the Sun sets on December 1st, and about 1 ? hours after the Sun sets on January 1st. Before the other stars appear, Venus can be detected just above the West-southwest horizon. It is the brightest and only 'star' there. Venus is full and relatively small (smaller than it was a few moths ago) because it is on the other side of the Sun. It will gradually become (from our point-of-view in space) a larger planet but with a smaller phase, as it revolves around the Sun. It revolves much faster than the Earth because it is so much closer to the Sun.

Saturn will rise about 10 PM on December 1st, and about 8 PM on New Year's Eve. Wait until midnight to view the ringed planet with a telescope - you'll be looking through less atmosphere, the atmosphere that you are looking through will be more stable, and there will be fewer interfering lights. The rings are observed edge-on during the first week of the month, then they will slowly (during the rest of the year) open.

The highlight of this month's observing takes place in the East-southeast at dawn during December's third and forth weeks - the grouping of Mercury, Jupiter, and Mars. At first, the group is so low that you will need binoculars. About to rise, the Sun will brighten the sky. It is too bright for the unaided eye to see the dim planets. Be sure that you don't let the Sun shine into the binoculars as it rises. But not to worry - you should be looking toward this group about an hour before Sunrise. On December 1st, the three planets should fit in a circle about 9 inches (the spread of your hand at the end of an outstretched arm) in diameter. Mercury continues to get lower at each dawn, and the Mars/Jupiter combination keeps getting higher. By the 10th and 11th, the three are about the thickness of a credit card apart. As a group on the 10th, these three planets will rise about 1 ? hours before the Sun. Don't miss this! A similar grouping occurred in 1974, and won't happen again until 2029. Mercury will continue to go lower, and Mars/Jupiter will continue their upward journey until there will be nothing to shout about.

December 10th, the moon will lie a finger-width from Saturn, while the grouping on Mars, Jupiter, and Mercury are less than a finger-width apart. On the 21st, a thin crescent moon is just a few finger-widths to the lower left of Venus in the west-southwest about 40 minutes after Sunset. Also on the 21st, the direct rays of the Sun reach the Tropic of Capricorn, marking the first day of winter for us. Cheer up - the daylight period will be getting longer, the days will be getting warmer, and the shadows will be getting shorter. The nights are still long (but they'll be getting shorter), there still are no bugs, and the air is still stable. Happy Viewing.