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 .

Storm Clouds

Photo of the Week.. Dark storms give way to clear skies.

Astronomy news for the week starting Friday, September 10, 2004.

Our Moon wanes through its crescent phase the early part of the week, descending each morning closer to the eastern horizon, finally passing the new phase on Tuesday the 14th. The morning of Sunday the 12th will present a special sight: the Moon tucked within the sickle of Leo, the classic zodiacal constellation that is now clearing the Sun. The evening of the 14th the Moon will not have cleared the Sun enough to be seen in the evening sky, but by the night of Wednesday the 15th look for the slim crescent glowing in western twilight.

This appears to be something of a "small body" week. The morning of Sunday September 12, the Moon will hang almost directly above little Mercury in the dawn sky, with the star Regulus in between the two, the bright twilight making observation quite difficult. Then on Wednesday the 15th, Mars quite invisibly passes conjunction with the Sun and thus swings into the morning sky. It will not, however, be visible in growing dawn until mid October. Moving on to even smaller bodies, two of the first four asteroids hit the headlines. The night of Sunday, the 12th, Ceres (the largest and first discovered) passes conjunction with the Sun. Only two hours later, Vesta, the brightest asteroid (actually visible to the naked eye) passes solar opposition. Smaller than any of the planets, Ceres has a diameter of only 915 kilometers (570 miles, just a quarter the size of the Moon), while Vesta is but 55 percent as large (but brighter because of higher reflectivity).

Larger bodies celebrate the morning sky, where you can admire wonderful Venus, which is still rising around 3 AM Daylight Time, and fainter (but still bright) Saturn, which lies above and to the right of Venus and pointed downward to by Castor and Pollux in Gemini.

Look for Sagittarius now low on the meridian to the south in early evening. Many constellations contain smaller beloved "asterisms," the most famed the Big Dipper of Ursa Major. Sagittarius is graced with not one, but two. The most notable is the upside-down (from our northern perspective) five-star "Little Milk Dipper," the name coming from its setting in the Milky Way. Add the stars to the west, and you get the "Teapot." Then look to an interesting gaggle of stars farther to the south. Beneath the Teapot is the graceful curve of Corona Australis, the Southern Crown, while down and to the left are Sagittarius's Alpha and Beta stars, which are curiously far from the brightest of the constellation. Farther south yet is modern dim Telescopium (the Telescope), while over to the west underneath the curve of Scorpius's tail is Ara, the Altar, which is lost below the horizon to those above about 30 degrees north latitude.
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