Astronomy news for the week starting Friday, December 21, 2007.
Wishes for the best of Holidays to all.
It's a busy week! The Moon
starts us off in its waxing gibbous phase
as it heads towards full the night of
Sunday, December 23rd, Christmas Eve-Eve, thereafter reversing
its phases and waning in the gibbous. Two
days before full, the waxing gibbous passes through perigee,
where it is closest to the Earth.
The evening of Saturday the 22nd finds it in northeastern Taurus to the south of Auriga. The following night
(Sunday the 23rd), the Moon takes on Mars, passing just barely
north of it (the planet occulted as seen from Alaska and western
Canada). Christmas Eve then finds the waning lunar disk smack in
central Gemini. Finally, the
night of Thursday the 27th, look for the Moon just south of Regulus in Leo to west of Saturn.
Two major events vie for attention. First, Mars passes its long-
awaited opposition to the Sun the night of Monday
the 24th, Christmas Eve, when it will rise at sunset, set at
sunrise, and cross the meridian high
to the south at local midnight, giving the red planet its best
visibility. The planet is now also in its fastest
retrograde (westerly) motion. The Earth then begins to pull
away from Mars, but the difference in position is so slow that Mars
will be nicely visible in the evening well into the summer of 2008.
Countering the event, Jupiter, nearly opposite Mars, passes conjunction with
the Sun the night of Saturday the 22nd. Becoming a morning object,
Jupiter will become visible in dawn toward the end of January.
The other major event is the start of
astronomical winter the night of Friday the 21st, the Sun
passing the winter solstice in Sagittarius at 12:08 AM Central Time
(1:08 AM EST, 11:08 PM PST, 10:08 PM PST). Winter thus actually
begins the morning of Saturday the 22nd in eastern North America,
the night of Friday the 21st in the western states and provinces.
At that moment, the Earth's axis will be tilted away from the Sun,
the Sun rises as far southeast and sets as far southwest as
possible, the days are shortest, nights longest, and the Sun is as
high at the south pole as it is ever going to get. From here on,
the Sun will begin once again to climb the sky toward the equator,
even as the days -- for awhile -- become still colder.
This is a good time to try to find one of the sky's larger
critters, Cetus, the sea monster
(or more benignly, the Whale). Look in early evening to the south
of Aries and just to the north of
the celestial equator for the faint ragged circle that makes its
head, the body falling to the southwest, ending in bright Deneb Kaitos. In the middle is
the fabulous variable star, Mira.