Skylights featured on Astronomy Picture of the Day

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Skylights featured three times on Earth Science Picture of the Day: 1 , 2 , 3 , 4 .

Crescent Moon

Photo of the Week.. A peaceful crescent Moon sets in the west, Earthlight barely visible.

Astronomy news for the short week starting Friday, September 5, 2003.

The Moon waxes through its gibbous phase most of the week, reaching full around noon on Wednesday, September 10. It will therefore be just shy of full when it rises the night of Tuesday, the 9th, just past the phase at Moonrise on Wednesday. The night of Sunday the 7th finds the Moon in the middle of the "cocked hat" figure of Capricornus (having passed south of Neptune during the day). The following evening (Monday, the 8th), the Moon will skirt south of Uranus, and will be found to the west of Mars. Passing the red planet during the day (and occulting it for part of the eastern hemisphere), the Moon will then be found to the east of Mars the night of Tuesday, the 9th.

Having passed opposition with the Sun, Mars is now rising before sunset, is well up in the southeast at the end of evening twilight, and is also crossing the meridian to the south before local midnight (about 12:30 AM Daylight Time). Retrograding -- moving westerly against the stars -- it is approaching Uranus, but cannot quite reach it to make a second conjunction for the year (the first and only occurring last June 20th). The red planet starts the year off brilliantly, at magnitude -2.9 (3.8 times brighter than the brightest star, Sirius), fading only to -2.1 by the month's end (still 1.8 times brighter than Sirius).

About an hour after Mars's meridian passage, Saturn rises in the northeast, beautifully tucked within the elongated box that makes the classical figure of Gemini, the ringed planet almost as far north as it can get. The other planets are effectively out of sight, Mercury passing inferior conjunction with the Sun on Wednesday, the 10th, when it is more or less between us and the Sun (not transiting it).

About as Saturn rises, so does Betelgeuse in Orion, a reminder that northern summer is slowly coming to an end as the stars of winter begin to press upon us. It is still summer, however, and early September is a fine time to catch the summer stars, as they wheel overhead and to the south as twilight falls, though Moonlight will get in the way. Look about halfway up to find Altair in Aquila, the Eagle, its two flanking stars looking like winglights on an aircraft (for which the trio has been taken). Down and a bit to the west is one of the more prominent "modern" constellations, Scutum, the Shield, which holds an especially prominent part of the Milky Way. You will have to go to the country and wait for the Moon to move on to see the Milky Stream, however. Directly below Scutum is the Little Milk Dipper of Sagittarius, which from a latitude of 30 degrees south (the southern tip of Africa, southern Australia, central Chile and Argentina) passes directly overhead.
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