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 .


Photo of the Week.. Memories of early autumn lie against the blue of the distant sky.

Astronomy news for the week starting Friday, December 3, 2004.

The week begins with the Moon just shy of its third quarter, allowing the skies to darken once again. After the passage of the phase on the night of Saturday, December 4, rather well before Moonrise in North America, the Moon wanes in its crescent, becoming ever thinner in the early pre-dawn sky.

Watch the Moon as it passes by stars and planets, marking them out one by one. The morning of Wednesday the 8th, our companion will appear just down and to the left of first magnitude Spica in Virgo. Look for Jupiter higher in the sky in western Virgo to the other side of Spica. The next morning, on Thursday the 9th, the Moon will help form a line that leans down and to the left, the Moon on top, Mars in the middle, and Venus below. To the left of the Moon will be much fainter Zubenelgenubi in Libra. By the morning of Friday the 10th, the positions will be reversed, the Moon now below Venus as they all climb out of eastern dawn. Of the three planets, Venus (at minus fourth magnitude) is by far the brightest, minus-second magnitude Jupiter next, Mars (second magnitude) by far last. Earlier in the week, the morning of Sunday the 5th, Venus and Mars come into conjunction, creamy-white Venus 1.3 degrees to the north of the more distant red planet.

Jupiter, well to the west of the Venus-Mars duo and now rising around 2 AM, slowly moves toward the evening sky. The evening itself is now graced by Saturn in Gemini, which clears the northeastern horizon around 7:30 PM. In contrast, innermost Mercury is quite invisible as it passes inferior conjunction with the Sun the morning of Friday the 10th as it passes from evening to morning.

'Tis the Earth in the news, though. While the shortest day in the northern hemisphere falls at the passage of the Sun over the Winter Solstice (on December 21), the earliest sunset takes place on Tuesday the 7th, the offset the result of the eccentricity of the Earth's orbit and the 23.5 degree tilt of the terrestrial axis, which together put the Sun rather well ahead of its average, smooth-motion position. While the morning Sun will keep rising later until well into winter, the evening Sun will begin to set later, giving us more light on the evening drive home.

High above in northern mid-evenings find Cassiopeia, the Queen of the ancient legend of Andromeda and Perseus. To the west is Cassiopeia's husband, King Cepheus, which is more difficult to find as it is not marked out by a slew of bright stars. Beneath the two figures find Polaris, the North Star, about which they nightly whirl. Directly opposite, and below the pole, lies the Big Dipper of Ursa Major, whose bowl is now tipped to "hold water," all of the figure circumpolar and visible from the far northern US and most of Canada.
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