Photo of the Week. Star colors can be vivid, as
witnessed by the cool red giant and (Mira-type) variable star, S
Coronae Borealis at the center of the picture. Varying over a 360-
day period between 14th magnitude (1000 times fainter than the
human eye can see alone) and barely-naked-eye visiblity, the star
was caught here near maximum. Some 1500 light years away, it is
larger than the orbit of Mars.
Astronomy news for the week starting Friday, August 19, 2011.
Our Moon fades away during the week. Starting in the waning gibbous phase, it quickly passes
through third quarter on the afternoon of
Sunday, August 21, then spends the rest of the week as a waning crescent (new Moon not reached until
Sunday the 28th). The night of Friday the 19th, the barely-gibbous
Moon will pass five degrees (the separation of the front bowl stars
of the Big Dipper) above
Jupiter, then the following night will appear rather well to
the east of the giant planet. Keep watching, and you will find the
rising quarter Moon just below the Pleiades of Taurus
the night of Sunday the 21st, while the following night the rising Moon
will glide to the left of
Aldebaran. Not done with its passages, the
waning crescent next encounters
Mars, seen to the southwest of the red planet the morning of
Thursday the 25th, to the southeast of it the following
morning.
With
Saturn setting just after twilight, with Mercury and
Venus much too near the Sun for visibility, Jupiter and Mars
are "it" for the ancient planets. Rising an hour after the end of
evening twilight, Jupiter is up in the east by 11 PM Daylight Time
(in southern Aries to the north
of the head of Cetus, the Sea
Monster), not crossing the meridian to
the south until the Sun is almost up
and even Jupiter disappears into the blue sky. Considerably
fainter, Mars then rises in the northeast around 2:30 AM from day-
to-day moving quickly against the bright stars of southern Gemini, the planet's brightness
between those of Pollux and Castor to the northeast. All that's
left is to note that Neptune, at the fringe of the planetary system, currently
six times farther from us than Jupiter, goes through opposition
with the Sun on Monday the 22nd, making for best visibility, though
one needs a telescope or good binoculars to see it.
Arcturus is still nicely visible
as a lonely bright orange star in the west after sundown, the star
the luminary of Bootes, the
Herdsman, which appears to stretch out to the northeast of the star
like a giant kite. Immediately to the east of the classical
figure, find the gentle curve of stars that makes Corona Borealis, the Northern Crown.
Going further to the east, we encounter dim Hercules, then bright Vega in pretty Lyra, then Cygnus the
Swan. Topped by Deneb, Cygnus
crosses the meridian shortly before midnight. Farther east are the
constellations of the coming
autumn.
