Skylights featured on Astronomy Picture of the Day

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Skylights featured nine times on Earth Science Picture of the Day: 1 2 3 4 5 6 7 8 9 -- Full List Restored!

Greenland 12

Photo of the Week. Planet Earth: the tenth of twelve in the "Flight across Greenland," going from east to west above the fantastic glacier and a river of ice. See full resolution.

Astronomy news for the week starting Friday, April 18, 2014.

With the eclipse over, the Moon is seen at the beginning of the week late in its waning gibbous phase. That ends with third quarter on the night of Monday, April 21, shortly after Moonrise in North America. During the remainder of the week we see the Moon fading as a waning crescent, rising ever later in the morning hours as it approaches Venus. The morning of Friday the 25th, the two will make a fine sight with the rising Moon up and to the right of the brilliant planet. The Moon passes perigee, its closest point to the Earth (5.5 percent closer than averate), on Monday the 22nd, less than a day after the third quarter.

Night after night, the planetary sky changes, albeit slowly. Now in the western sky as darkness falls, Jupiter sets shortly after local midnight. But you still have a couple months left to enjoy the bright planet, which quite overwhelms everything else. To the southeast, Mars is already well up by the end of dusk nicely to the northwest of Spica in Virgo, Mars's retrograde motion obvious over only a few nights. By midnight Daylight Time, the red planet is crossing the meridian to the south. Mars is followed by dimmer but still bright Saturn, which rises in the southeast near twilight's end still within the confines of Libra. The ringed planet then crosses to the south about 2:30 AM. Wait a couple hours and you get to see Venus popping up over the eastern horizon. The second planet from the Sun crosses a bit of a divide by rising just as morning twilight begins, no longer (for now) to be seen in a fully dark sky.

From the large to the small, we have a bit of a meteor shower this week, the Lyrids. The shower peaks the morning of Tuesday the 22nd, the meteors appearing to come out of the constellation Lyra. Rather sparse to start with, producing 10 or 20 meteors per hour, their number will be reduced by the bright quarter Moon. The Lyrids are the debris of long-period Comet Thatcher of 1861. It won't be back for some 260 years.

Leo, with its distinctive "Sickle" that ends in Regulus, crosses the southern meridian around 10 PM as we approach the days of summer. Following along behind it is Virgo with Spica. The two stars are closely connected by the ecliptic, the autumnal equinox falling roughly midway between them. To the west of Leo, between it and Jupiter-embracing Gemini, lies one of the dimmer constellations of the Zodiac, Cancer the Crab, which holds the Beehive star cluster and once held the Summer Solstice (hence the Tropic of Cancer). That it no longer has the solstice is the fault of precession, the 26,000 year wobble in the Earth's axis.
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