SKYLIGHTS
Astronomy news for the week starting Friday, January 29, 1999.
Happy birthday to the Star of the Week, born one year ago. The
Moon passes through its full phase this week on Sunday, January 31
about 10 AM well after it sets, at the same time undergoing a
penumbral eclipse not visible in North America. Not that it
matters, as penumbral eclipses, in which the Moon passes through
the partial shadow of the Earth, are only barely visible anyway
(from the Moon, you would see the Earth cutting off only a part of
the Sun). The Moon will also pass over the star Regulus the
evening of Monday, February 1, the event visible only in far
northeastern North America, most of us seeing the Moon just to the
left of the star after moonrise.
The day after, February 2, is special as Groundhog Day, a genuine
astronomical holiday, one of the four "cross quarter" days in which
the Sun is just between an equinox and a solstice, Groundhog day
marking the midway point between the beginning of winter and the
beginning of spring. Other such days are May Day Eve and
Halloween. Our astronomical roots run deep indeed.
Four naked-eye planets ply the sky this week, Venus low in the
southwest in twilight, Jupiter much higher in the southwest, and
Saturn to the left of Jupiter, the three, along with the rising
Moon, marking the ecliptic, the apparent path of the Sun. In the
morning, Mars stands beautifully to the left of the bright star
Spica. This also is another week for conjunctions, Uranus aligned
with the Sun on Groundhog Day Eve (not a holiday) and Mercury in
superior conjunction, when it is on the other side of the Sun, on
Wednesday, February 3. The next day, the asteroid Vesta does the
reverse, coming into opposition with the Sun about halfway between
the "Sickle" of Leo and the "Beehive" star cluster in Cancer (which
makes a faint smudge in a dark sky). Vesta, the fourth asteroid to
be discovered and, with a 300 mile diameter the third largest, is
very bright. Even though 2.4 times as far from the Sun as we are,
the little body is, at opposition, just visible to the naked eye.
Though moonlight will make it impossible to see, you know it is
there, one of tens of thousands of asteroids in the debris belt
that lies between Mars and Jupiter, enormous numbers of small ones
wandering in to hit the Earth as meteorites.
