Skylights featured on Astronomy Picture of the Day

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Skylights featured nine times on Earth Science Picture of the Day: 1 2 3 4 5 6 7 8 9


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.
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