SKYLIGHTS

Astronomy news for the week starting Friday, November 12, 1999.

The Moon, appearing as a lovely crescent early in the week, grows toward its first quarter, passing the phase the morning of Tuesday the 16th shortly after moonset. While the Moon is still a thin crescent, be sure to admire the earthlight on the Moon's nighttime side, which makes the entire lunar disk visible. The crescent will make a nice couple with Mars, appearing in southwestern evening twilight up and to the right of the red planet the night of Friday the 12th and up and to the left the following evening. On successive days, Sunday the 14th and Monday the 15th, the Moon will pass Neptune and then Uranus, actually occulting (or covering) them, neither occultation visible in the western hemisphere.

A covering of sorts involves a major event of the week if not one of the whole year, as on Monday the 15th, between about 3 and 4 PM Central Time (4 and 5 PM EST, 1 and 2 PM PST), little Mercury will transit across the face of the Sun, appearing as a tiny black dot against the extreme edge of the solar disk. (DO NOT TRY TO OBSERVE THE EVENT YOURSELF AS THE SUN IS FAR TOO BRIGHT TO LOOK AT!) Every 116 days, Mercury passes its inferior conjunction, when it is between us and the Sun. But because of the tilt of the orbit, the planet usually misses, passing above or below the Sun. But in intervals of 7 and 14 years, and only in May and November, Mercury passes its conjunction in exact alignment and make a visible solar transit. The last transit was on November 5, 1993. Transits of Mercury are historically important for the determination of Mercury's orbit, for determination of longitude, and for showing that the little planet has no significant atmosphere. Since like Mercury, Venus is also closer to the Sun than Earth, it too can transit. Venusian transits are much rarer, however, the last one taking place in 1882, the next not until June 8, 2004.

THE major event, however, is the continuing possibility of a great display of Leonid meteors the morning of Thursday, the 18th. Every 33 or so years, the Earth passes close a clump of debris from Comet Temple-Tuttle. If we pass through the cloud of dust and rocks, we could see a spectacular meteor storm -- that of 1833 produced tens of thousands of meteors per hour, as did the one of November 17, 1966. Though last year's shower displayed a number of large "fireballs," there was no major storm. The odds are long, but who knows, maybe it will hit this year. It is best to look in the morning hours after Leo (which contains the radiant point) rises. If nothing else, you can always admire the stars in a dark, moonless sky.