Astronomy news for the week starting Friday, December 19, 2008.
Best to all and wishes for a fine holiday season.
The Moon starts the celebration by being in its third quarter on
Friday, December 19. The past couple weeks have been bracketed by
lunar phases of the moment. Now we start to stretch things out, as
the rest of the week is spent with the Moon in its waning crescent
phase, new
Moon not passed until Saturday the 27th (the interval between
exact phases being about 7 1/3 days). Your last view of the
crescent could be had in cold eastern twilight the morning of
Thursday the 25th, Christmas morning, should you want to venture
out, the Moon just having passed Antares in Scorpius.
On the other side of the day and sky, the early evening remains
studded with
Jupiter and Venus. Pulling
ever farther apart since their dramatic conjunction, Jupiter sets
ever earlier (just after the end of twilight), while Venus sets
ever later, not until after 8 PM. The planetless gap (ignoring the
dim outer ones) is no longer as large, with Saturn now
rising in the late evening hours, around 11 PM. In far
southeastern Leo, well to the
southeast of Regulus, Saturn is
barely moving easterly as it approaches the boundary with Virgo. Returning to the outer
planets, Pluto invisibly
passes conjunction with the Sun on Monday the 22nd,
Pluto some six degrees to the north of the Sun thanks to its large
orbital tilt.
Now it's back to Earth, as the Sun
passes the Winter Solstice in Sagittarius at 6:04 AM CST (7:04 EST,
5:04 MST, 4:04 PST, subtract another hour each for Alaska and
Hawaii) on Sunday the 21st, marking the beginning of northern
winter and the northern hemisphere's shortest day (and for
astronomers, the longest night). At that time, the Sun will be as
far south as it gets (23.4 degrees south of the celestial equator),
will pass overhead at the Tropic of
Capricorn, and, except in the Arctic and Antarctic, will rise and
set as far to the south of east and west as possible.
Just before Venus sets, Sirius --
the sky's brightest star -- rises, and the winter constellations begin to come into full
glory. Now is the time to admire great Orion as he climbs the eastern sky, the Hunter
instantly recognizable by his three-star Belt. But don't forget those of autumn. In mid-
evening, Pegasus has moved off
to the west, while Andromeda
still lies close to overhead. If the sky is dark, between the Great Square of Pegasus and
Orion you might locate the rounded dim head of the villain of the
Andromeda myth, Cetus, the Whale
or Sea Monster.
