Photo of the Week. Sunset from 25,000 feet, the Sun
seen through a deep layer of haze.
Astronomy news for the week starting Friday, October 4, 2013.
It's not often that the lunar week (as defined by Skylights) starts
so perfectly. But here we are with the Moon in its new phase, passing by the Sun, as we open our new week
on Friday, October 4. Given the phase
cycle of 29.5 days, just a bit over four weeks, our week is
then occupied fully by the waxing
crescent. With a clear sky and western horizon, you might
first pick it up in twilight the evening of Sunday the 6th. During
the early part of our week, as the sky darkens the entire lunar
disk is visible, with the nighttime side of the Moon illuminated by sunlight
reflected from a bright Earth. As the crescent grows, the effect
diminishes, and is lost well before the first
quarter, which is passed on Friday the 11th. Watch as the
crescent sweeps through the southern part of the Zodiac. The evening of Monday the
7th, the Moon will appear to the right of very obvious Venus.
By the following evening, the Moon will be above the planet, with
much fainter Antares of Scorpius down and to the left, the
three making a nice triangle. On Thursday the 10th, the Moon will
pass perigee,
where it is closest to the Earth.
Rather difficult to see since it cleared the Sun last March, Venus
is now climbing out of western evening twilight, setting around
half an hour after the sky is fully dark. It's hard to miss.
Then we have a long wait until Jupiter rises, the planet making a grand appearance
in the northwest as it comes up in Gemini around midnight Daylight Time southwest of Castor and Pollux. The giant planet then rises
high, invisibly crossing the meridian
at sunrise. With Mars moving much faster to the east against the stellar
background, Jupiter and Mars are now well separated, the red planet
rising around 3 AM Daylight. Now seriously in Leo, Mars makes a fine contrast with Regulus, which lies just to the east
of it. Meanwhile, back in the west, even though Mercury passes greatest
eastern elongation with the Sun on Wednesday the 9th, it is so low
as to be overwhelmed by twilight. The little planet invisibly
passes five degrees south of Saturn a day later.
Look high in mid evening for Cygnus, the Swan, which, turned upside down, becomes
the Northern Cross. At the top is bright Deneb (the Arabic name referring to
the Swan's tail), while at the foot we find much fainter Albireo (whose name has no meaning
at all). Deneb is the northeast anchor of the Summer Triangle, which also
consists of bright Vega to the west
and Altair to the south. Between
Albireo and Altair flies Sagitta, the Arrow, which looks just like what it is
supposed to be. It makes a fine pairing with the little distorted
box of stars to the southeast that forms most of Delphinus, the Dolphin. In the
northwest, watch the handle of the Big Dipper as it prepares to sink below the pole.
