SkyWatch

January 2002

By Steve Stefanik

January 1st, the first day of the first month of the new year, greeted us with the opposition of Jupiter the giant Jovian planet which currently is in the constellation Gemini. Look toward the east for the twin first magnitude stars Castor and Pollux below and to the left of the familiar "V" of the constellation Taurus and you’ll spot the huge -2.7 magnitude brilliant white wanderer near them with just your eyes. During this time the planet rises about the time the sun sets and sets about the time the sun rises. It is also at its brightest because it is at its closest point to the sun in its orbit and directly opposite us from it. It doesn’t get any bigger or brighter at this time and decreases in size and brightness with each passing winter night in the coming months. This is the best time to get a glimpse of it through a telescope however. You’ll be able to see detailed features of its atmosphere including its "Great Red Spot" which has been swirling around for centuries as well as smaller white spots and festoons.

The planet Mercury also puts on quite a performance low in the southwest just after the sun sets the first half of the month. Watch where the sun goes below the western horizon and about 30 minutes later you should notice a –0.6 magnitude gleaming star-like object just above the horizon where the sun had set. That’s it. It doesn’t remain in view for long because this speedy little planet orbits the sun in only 88 days and doesn’t stray very far from it. It reaches its greatest elongation (furthest angle from the sun) of 19 degrees on the 11^th and drops out of view by the 19^th.

Saturn, the ringed planet, is high in the eastern sky in the constellation Taurus the bull. Having reached opposition just this past December, it is still very bright at magnitude –0.3. It is very near the first magnitude star Aldebaran, which is similar in brightness and color. If you have any doubt, look at them both through binoculars or even a small telescope and its rings will be revealed. During this year’s appearance the rings are tilted so that the shadow of the planet cast by its position in relation to the sun, can be seen projected onto the rings. If you have a telescope you may also spot several of the biggest of its 28+ moons.

The planet Mars is still a "naked-eye" object in the southwest after the sun goes down. Although it is considerably dimmer than it was, at +1.0 it is the brightest object in that part of the sky among the dim stars of the constellation Pisces the fish. Even through a telescope it is too small and too far away now to make out any details on its surface. We’ll have to wait another two years.

The remaining planets, Venus, Neptune, and Uranus are obscured by the glare of the sun this month. Venus will return to view next month as an "evening star" in the west.