Skylights featured on Astronomy Picture of the Day

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Skylights featured on Earth Science Picture of the Day: 1 , 2 , 3 , 4 , 5 , 6 , 7

Ring Nebula

Photo of the Week. The ghostly Ring Nebula in Lyra, M 57, was formed by the ejecta from the dying star in the middle. While there are many far-more- magnificent images of the famed "planetary nebula" (a misnomer, meaning merely "disk-like"), this is much the way it looks in an amateur telescope. (University of Illinois Prairie Observatory.)

Astronomy news for the week starting Friday, February 16, 2007.

On Saturday, February 17, the Moon once again begins its monthly round with its new phase, as it has for more than 50 billion times since it was born in what was probably a giant collision of a small planet with the primitive Earth. No one really knows, but it is the only theory that seems to work and to explain the lunar characteristics, especially the severe lack of iron.

Look for the debut of the familiar slim crescent low in western twilight the night of Sunday the 18th, when it will first be visible. The following twilit evening, though, that of Monday the 19th, you won't have to seek the Moon out, as it will be prominent just above brilliant Venus, the two making a near-classic pairing. Even the night of Tuesday the 20th they will still make a nice sight in the evening sky. Wait until the heavens darken a bit so you can admire Earthlight on the lunar nighttime side, that facing away from the already-set Sun. Though the Moon will look near new to us, from the Moon, the Earth will be near full, and will brightly illuminate the lunar landscape. As the crescent fattens, Earthlight fades away.

The remainder of the planetary night belongs to the two giant outer planets, Saturn and then Jupiter. Just past opposition to the Sun, the ringed planet is already risen by sunset and is well up in the east by the time the sky darkens. To the east of it lie Regulus and then the rest of Leo. Saturn transits the meridian high to the south and sets just before sunrise. For a time after Jupiter rises around 2:30 AM, they share the sky. Far to the south of the equator, Jupiter resides just to the east of Antares in Scorpius, and can be seen approaching the meridian to the south as twilight brightens the morning sky. Mars, well to the east of Jupiter, remains difficult to find, as it does not rise until dawn begins. The other planets are even more out of sight.

The beauty of the winter sky is in part due to great Sirius, the brightest star in our sky. Far from the most luminous (that honor going to the southern hemisphere's Eta Carinae), it seems so lustrous mostly because it is quite close to us, a mere 8.6 light years away. The star stands at the top of one of the most prominent of constellations, Canis Major, the Larger Dog. Quite overwhelmed by Sirius is the faintest of the first magnitude stars, Adhara (Epsilon Canis Majoris), the brightest of a prominent triangle seen toward the south. Much farther down from Sirius, and visible only south of about 35 degrees north latitude is Canopus, Alpha Carinae, the second brightest star in the sky, one that side by side would shine vastly brighter than Sirius.
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