SKYLIGHTS

Astronomy news for the week starting Friday, March 23, 2001.

The Moon passes through its new phase on Saturday, March 24th, and for a couple days is invisible. The crescent will appear in western evening twilight the night of Monday, the 26th (though under ideal conditions the thin crescent will be visible after sundown the night of Friday, the 25th). As the crescent waxes, it will pass beneath Saturn the night of Wednesday the 28th and then between Jupiter and Aldebaran the night of Thursday, the 29th, the tilt of the lunar orbit taking the Moon somewhat to the south of the two planets. Though Jupiter and Saturn are both moving well into the evening western sky, both will be nicely visible through April and into May as they make their way eastward against the stars of Taurus.

Venus, however, says farewell. The planet will pass inferior conjunction with the Sun, when it is between us and the Sun, on Thursday, the 29th. "Between us and the Sun" is pushing the definition a bit, however, as the tilt of the orbit causes the planet to pass a full 8 degrees north of the Sun, and causes it both to set after sunset and rise before sunrise. By early April, Venus will be nicely visible in the northeastern dawn sky, and will dominate the morning until near the end of the year.

At about the same time, on Tuesday the 27th, the asteroid Vesta also passes conjunction with the Sun. Vesta's proper name is 4 Vesta, as it was the fourth asteroid discovered, by Heinrich Olbers in 1807. The third largest asteroid, some 500 kilometers across (15% the size of the Moon), Vesta is unusual in that it is the only asteroid visible to the naked eye (though just barely).

Olbers is famed as the promulgator of "Olber's paradox," which can be traced through Edmund Halley, perhaps even to Kepler. You can make a profound cosmological observation any clear night. If the Universe is static, unevolving, and infinite, any line of sight should wind up at a star. Therefore the night sky should be at least as bright as the surface of the Sun! Yet the night sky is dark. The Universe can therefore not be static, unevolving, and infinite all at the same time. The resolution of the paradox is that the Universe is expanding and that it is evolving, that stars do not live forever, but are born and die.

The new Moon of course gives us the chance to admire these stars. By 8 PM or so, Orion is to the west of the meridian, and from mid- northern latitudes, Gemini is close to overhead, Procyon in Canis Minor nearly due south. Look a bit to the east of Gemini (between Gemini and rising Leo) to see if you can spot the famed Beehive cluster in dim Cancer.