Skylights featured on Astronomy Picture of the Day

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

Halo with Subsun

Photo of the Week.. The view from an aircraft window shows the lower half of the 22-degree halo around the Sun caused by refraction of sunlight through ice crystals. Below it is a bright "subsun" created by reflection from those same crystals. A faint arc tangential to the bottom of the halo produced by spinning pencil-shaped crystals connects the two. (This image appeard on the Earth Science Picture of the Day for March 4, 2003.)

Astronomy news for the ten day period starting Friday, March 21, 2003.

The next Skylights will appear on Monday, March 31. The Moon moves through its last quarter this week the night of Monday, March 24, rather well before Moonrise in North America. The morning of Tuesday, March 25, it appears to the southwest of Mars (now in Sagittarius), the following morning to the southeast. Then on the morning of Saturday, the 29th, the Moon will make a beautiful pairing with bright Venus, which will lie up and to the left of the lunar crescent.

The week is host to several invisible (or close to invisible) events. On Friday the 21st, Mercury goes into superior conjunction with the Sun, where it is on the other side of the Sun from us, and -- if you could see it -- in its full phase. Two days later, Pluto is "stationary" against the background stars of Ophiuchus (well off the ecliptic), and begins its small retrograde motion. Then on Wednesday the 26th, Vesta, the third largest asteroid (500 km, 310 miles, in diameter) comes into opposition to the Sun in the constellation Virgo. Though not the largest asteroid (one of the broken bodies between Mars and Jupiter), Vesta is the brightest because of its high reflectivity, and is actually visible to the naked eye, the only asteroid that is. On Thursday, the 27th, the Moon passes well to the south of Neptune, and then on the morning of Friday the 28th, Venus makes an extraordinarily close pass to Uranus , only 3 minutes of arc to the north. Twilight, however, will render this event very difficult to see. Such events conclude with the Moon passing south of Uranus on the morning of Saturday the 29th (about the same time it passes Venus).

While Venus is dropping lower in the southeastern dawn sky, rising just after the onset of twilight, the big planets still dominate the evening. Saturn , in Taurus, is to the west of the meridian (to the south) at the end of twilight, while Jupi ter crosses to the south in Cancer around 8:30 PM. Look for the Beehive cluster just to the northwest of it.

March is the traditional time for the evening rising of Leo, which, more than any other constellation, marks the beginning of northern hemisphere Spring. Due north of it lies the very obscure constellation Leo Minor, the Smaller Lion, a modern artifact of the sky. To the northwest of Leo, above Cancer and Gemini, lies another that is just as obscure, Lynx -- not surprisingly, a Lynx (the original name "Lynx sive Tigris," the "Lynx or Tiger." Lynx marks the space between Ursa Major and Auriga. Some of it was considered by the Greeks to be an "amorphous" region of Ursa Major. Thirty-eight such "modern" constellations dot the sky, many in the deep southern hemisphere that the ancients could not see. If Lynx is too faint to see, at least admire Leo with its bright star Regulus.
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