Photo of the Week. Colorful autumn grasses salute the
blue sky.
Astronomy news for the week starting Friday, December 11, 2009.
This is the week of the new Moon. That's about it, have nice
day... No wait, there has to be more, though we might have to look
for it a bit. Given that the new Moon does
not take place until late in the week, the morning of Wednesday the
16th, the Moon must spend most of our period in the waning crescent phase. As it thins in the
morning sky, your last look at it will be the morning of Tuesday
the 15th, when it will be barely visible in twilight and ultra-
thin. You'll then possibly see the waxing
crescent (with difficulty) in the western evening sky the night
of Thursday the 17th, also thin, but reversed in direction from the
morning crescent. Better to wait until Friday night.
Sadly, there are no planetary passages this week except for one
past Mercury the morning
of Friday the 18th, which will be quite unobservable since Mercury
is now an evening object that will pass greatest eastern elongation
the same day, so you might want to take a look for a bright "star"
close to the southwestern evening twilight horizon.
Venus is gone from the morning sky, but you
can still be amused and charmed by the three outer ancient planets.
First up is Jupiter. Having moved seriously into
the western sky, the giant planet now sets pretty early, by around
9:30 PM. But it's replaced by Mars, which
rises almost as the Big Guy sets, less than half an hour earlier.
While Jupiter still hangs out in northeastern Capricornus, passing north of Deneb Algedi and Nashira (Delta and Gamma Cap), Mars
-- on the other side of the sky -- flies through western Leo to the west of the constellation's
famed "Sickle." Brightening
mightily as Earth approaches it, the red planet (which is not quite
so red, but more yellow-orange) has reached magnitude zero, where
it rivals the brightest stars (Jupiter, though, notably brighter).
Then after a goodly wait watching the stars, we come to Saturn, which climbs upward from the eastern horizon
in Virgo to the west of Spica about half an hour after
midnight.
Ah, but wait again, as the week contains a wonderful surprise, the
Geminid meteor
shower, which will peak the night of Saturday the 12th (and the
morning of Sunday the 13th). One of the best showers of the year,
the Geminids, which appear to come out of the constellation Gemini, are the leavings of near-
dead Comet Phaeton,
which was once thought to be an asteroid. With the Moon out of the
way, in a dark sky you might see as many as 120 meteors an hour.
You might also get a decent show the nights before and after as
well.
With that great harbinger of fall, Fomalhaut (in Piscis Austrinus, the Southern Fish) moving off to the
west, it's time to admire the constellations of winter, particularly
mighty Orion, whose stars rise in
the east as the sky becomes dark. By mid-evening, Sirius, the brightest star in the
sky, the "Dog Star" of Canis Major,
follows in the southeast.
