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.