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. Trees praise the sky.

Astronomy news for the two week period starting Friday, May 27, 2011.

We begin our fortnight with the waning crescent Moon, which heads towards new on the afternoon of Wednesday, June 1. Your last view of the crescent in eastern twilight will be on the morning of Tuesday, May 31, after which it will appear as an ultrathin waxing crescent during early western twilight the evening of Thursday, June 2 (in both crescent phases the nighttime sides of the Moon aglow with light reflected from Earth). Growing fatter, the Moon finally passes first quarter on Wednesday the 8th during evening twilight for much of North America. We then get to see a bit of the waxing gibbous. Skylights begins on Friday the 27th with the Moon at its apogee, where it is farthest from Earth.

Watch the mornings of Sunday, May 29th through Tuesday the 31st to see an amusing interplay with the planets, first with Jupiter (the Moon above the rising planet), then Mars and Venus (the Moon above them and to the left of Jupiter, and finally passing above nearly invisible Mercury. Switching to the evening sky, the growing crescent will grace southern Gemini below Castor and Pollux on Friday the 3rd, then will appear down and to the left of the stars the following night and immediately to the left the night of Sunday the 5th. A few nights later, on that of Thursday the 9th, we find our Moon to the southwest of Saturn and to the west of Spica, the three making a fine triangle.

This new Moon is a bit of a special one, as it crosses in front of the Sun to produce a solar eclipse. But don't bother watching, as it is both partial and polar. Only northern Alaska, northern Canada, Greenland, and Siberia will see much of anything.

As is obvious from the progression of the waning crescent, the four morning planets no longer clump together but instead are now in a nice line, starting with Jupiter up and to the right, then proceeding down and left through Mars, Venus, and Mercury, the last three difficult-to-impossible to make out. But it is easy to admire Jupiter, which rises shortly before the start of dawn.

The star of the show, though, remains">Saturn, which during the middle of our fortnight crosses the meridian to the south just past sundown, so will appear in the southwest after darkness falls, not setting until around 2:30 AM, shortly before Jupiter rises. Still set to the northwest of Spica, as our period ends the ringed planet will stand but a quarter of as degree from much fainter (third magnitude) Porrima (Gamma Virginis, itself a remarkable telescopic double star). Finally, in lesser planetary news, Neptune begins retrograde motion (to the west against the stellar background near the Aquarius-Capricornus border) on Friday the 3rd.

Two icons of the sky round their respective poles, the Big Dipper in the north, the Southern Cross at about the same polar distance in the south. From the tropics you could watch them both, the two on a great circle that connects them to the North and South Celestial Poles.
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