Astronomy news for the week starting Friday, February 2, 2001.
The Moon grows through its waxing gibbous phase this week toward
full, the phase reached close to midnight in North America the
night of Wednesday, February 7, within the confines of Leo, near
Regulus. Only 9 hours before full, the Moon also passes perigee,
its closet point to the Earth, which increases the amount of
moonlight to its maximum, 11 percent more than average, and 25
percent more than when the Moon is at apogee. As the Moon
approaches full, it passes south of Saturn the morning of Friday
the 2nd and south of Jupiter on the afternoon of the same day.
That night, Friday the 2nd, the Moon will appear just to the
southeast of the giant planet, the Moon and two the planets
appearing together high in the constellation Taurus.
Today, Friday the second, is a bit of a holiday (though no one
seems to get the day off). Groundhog Day (Candlemas in Britain) is
one of four "cross-quarter" days that split the difference in time
between the solstices and the equinoxes. Groundhog Day, in fact an
astronomical holiday, is halfway between the day on which the Sun
passes the winter solstice in Sagittarius to mark the beginning of
astronomical winter (in the northern hemisphere) and the day of
vernal equinox passage in Pisces, which marks spring. In other
words, we are halfway there, to spring. The other cross-quarter
days are May Eve, the night before May Day (May 1, "Beltane" in
Scotland and Ireland), All Saints' Day Eve -- Halloween -- in
October, and (in Britain) "Lammas Day," a harvest celebrating, on
August 1. Astronomical roots, which include our common time-
keeping units, go very deep.
Nothing quite dominates the sky like Orion, his season now best
upon us. No training is needed to find the three bright stars of
his belt (now high to the south in mid-evening), which the Arabians
referred to as the "String of Pearls." The trio very closely ride
the celestial equator, rising due east and setting due west. To
the upper left is the reddish supergiant Betelgeuse, to the lower
right blue-white Rigel. Hanging down from the Belt is the three-
star Sword, the middle star of which is embedded in the great Orion
Nebula, which marks a region of past and intense star formation and
which is easily visible with the least optical aid. Unlike most
constellations, which are random groupings of stars, most of
Orion's stars are physically related in the vast "Orion OB1
Association," an expanding group of hot blue-white stars that were
born more or less at the same time within the space now occupied by
the great constellation. Well down and to the left, pointed to by
the Belt, is Sirius in Canis Major, the brightest star in the sky.
If you live far enough south, below about 35 degrees south
latitude, you can also see the second brightest star, Canopus in
Carina, the hull of Jason's ship, Argo.