Skylights featured on Astronomy Picture of the Day

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Skylights featured five times on Earth Science Picture of the Day:
1 , 2 , 3 , 4 , 5

Cloud Shadows

Photo of the Week.. Dramatic cloud shadows proclaim the glory of the sky.

Astronomy news for the two week period starting Friday, September 23, 2005.

Skylights now resumes its normal weekly schedule.

We start the week with the Moon not quite in its last quarter, the phase reached the night of Saturday the 24th about the time of Moonrise in North America. The remainder of the week is spent in the waning crescent phase as new Moon is approached. By the end of the week, the Moon will appear as a slim crescent in the eastern dawn sky. The only lunar passage of note is that between the Moon and Saturn, our companion gliding north of the ringed planet the night of Tuesday the 27th, though you will not see the event until Saturn rises around 2:30 AM, Daylight Time. Just half a day after this visitation, the Moon passes apogee, where it is farthest from the Earth in its monthly round.

With Jupiter setting in mid-twilight and pretty much out of sight, the early evening belongs to brilliant Venus, which, while shifting south, is getting marginally higher (for the same interval after sunset) and not setting until a bit after twilight is over. But around 9 PM, half an hour after Venus leaves us, Mars ascends the eastern sky as it prepares to move from eastern Aries into western Pisces. The red planet, now brighter then the brightest stars, then holds forth until the rising of Saturn. Barely moving against the background stars, Mars begins retrograde motion on Saturday, October 1, just after Skylights' current week comes to an end.

The Sun, having just passed the autumnal equinox, while always moving a degree per day to the east against the background stars, is also moving as rapidly as possible to the south, at a rate of about four-tenths of a degree per day. The effect is very noticeable in the day-to-day times of sunrise and sunset, sunrise quickly coming ever later, sunset earlier, the points of sunrise and sunset now just to the south of due east and west.

Early September is a time to praise the Milky Way, the great white band that is made of the combined light of the billions of stars in the disk of our Galaxy. Bright city skies make it difficult, if not impossible, to see, but viewed from the dark countryside, it is spectacular and deeply moving. Watch it come out of the northeast through rising Cassiopeia, then climbing nearly overhead as it passes through Cygnus and across its bright star Deneb. Splitting in two as a result of the dark dust clouds in the Galaxy's plane (where stars are born), the Milky Way plunges south through Aquila, Scutum, and Sagittarius, where it has its heart, only to disappear -- for unlucky North Americans -- below the southern horizon.
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