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 .

Poniatowski's Bull

Photo of the Week.. The "vee" of stars at center represent the modern asterism "Poniatowski's Bull," which commemorates Stanislaus Poniatowski, King of Poland from 1764 to 1795. At far right is Rasalhague (Alpha Ophiuchi). Down and to the right of the "vee," just above Cebalrai (Beta Oph), is the star cluster IC 4665.

Astronomy news for the week starting Friday, September 17, 2004.

The week's events are compacted in its middle. First up is the first quarter Moon, the phase passed on Tuesday the 21st shortly before moonrise in North America. Just a day later, the Moon passes perigee , where it is closest to the Earth. Watch in the evening hours early in the week for the growing crescent as the Moon passes through northern Scorpius, seen to the right of Antares the evening Sunday the 19th, to the left the following night. Then later in the week admire the waxing gibbous as the Moon heads towards full.

Next up is giant Jupiter, which on the same day as the Moon passes first quarter (Tuesday the 21st) passes conjunction with the Sun and moves over into the morning sky. You'll see it rising out of morning twilight in mid-October, quickly passing Mars, the latter keeping better orbital pace with the Earth and thereby taking a long time to rise into a dark morning sky. While these two planets now remain out of sight, Venus and">Saturn shine gloriously before dawn graces the sky, Saturn slowly pulling away from much brighter Venus.

Lastly, but most importantly, the Sun passes the autumnal equinox in Virgo to mark the beginning of northern fall (and southern-hemisphere spring) at 11:30 AM Central Daylight Time (12:30 PM EST, 9:30 AM PST, 8:30 AM in Alaska, and 6:30 AM in Hawaii) on Wednesday, the 22nd (early this year because of leap year). At that time, the Earth's axis will stand perpendicular to the line to the Sun, the Sun will pass overhead at the Earth's equator, will technically set at the North Pole, and rise at the South Pole. (The half-degree angular size of the Sun and refraction by our atmosphere will make it linger above the horizon at the north pole for a couple days, and advance rising at the south pole.) The Sun will thereafter rise progressively farther to the south of east, and set farther to the south of west as the days shorten in the northern hemisphere and the weather chills.

As Scorpius and Antares move off into western twilight, so does one of the giants of the pantheon of constellations, Ophiuchus, the Serpent Bearer, which lies directly to the north of Scorpius. So too does the Serpent itself, Serpens the only constellation that comes in two separate parts, Serpens Caput (the "head," to the west of Ophiuchus) and Serpens Cauda (the "tail," to the east). Directly north of Ophiuchus is Hercules, and yet farther to the north is the head of Draco, the Dragon, with two curving paths of stars lying between it and Polaris, which stands nearly unmoving near the North Celestial Pole.
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