Photo of the Week. Clearing clouds reveal the waxing
crescent Moon and a lonely star.
Astronomy news for the week starting Friday, August 22, 2008.
The Moon
fades away this week. Beginning in its late
waning gibbous phase, it passes third
quarter the night of Saturday, August 23, then spends the
remainder of our period as a waning
crescent, new Moon to be passed on Saturday the 30th. With a
clear eastern horizon, you might be able to admire the last glimpse
of the narrow crescent the morning of
Friday the 29th. Two days after third quarter, on Monday the
25th, the Moon passes perigee, where
it is a bit over five percent closer to the Earth than average. As
the crescent wanes, look for Earthlight on the nighttime side of
the Moon.
The Moon passes no planets this week, in part because so many are
ganged together over in western twilight, unfortunately pretty much
out of sight.
Saturn sets just after sunset, followed by
Mercury (which is making a poor western appearance), then
Venus and Mars,
all going down in twilight. The only one with a hope of being seen
is Venus, and only because of its great brilliance. Neptune is up in
the east at the end of twilight, followed by Uranus as
twilight ends, but these require a knowledge of exactly where to
look as well as optical aid.
That leaves us once again with
Jupiter, which now dominates the evening sky within the
confines of northern Sagittarius.
The giant of the Solar System (11 times the diameter of Earth) can
now be seen crossing the meridian to
the south around 9:30 PM Daylight. You can admire it for several
more hours until it sets just after 2 AM, when Uranus transits the
meridian and Betelgeuse in Orion rises. Jupiter is in a fine
stellar setting a couple degrees due north of the bright star Nunki (Sigma Sagittarii) in the bowl
of Sagittarius's Little Milk
Dipper.
Several first (and zero) magnitude stars dot the evening sky, the
set dominated by the Summer
Triangle of Vega in Lyra (nearly overhead in early
evening), Deneb in Cygnus (east of Vega), and Altair in Aquila (to the south). To the far northwest find
orange Arcturus in Bootes (the brightest star of the
northern hemisphere), while to the far south you can admire Antares in Scorpius.
