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


Photo of the Week. An intense partial rainbow seems to shoot from the sky.

Astronomy news for the week starting Friday, September 10, 2010.

The Moon, having passed its new phase late last week, is now in a growing crescent nicely visible in evening as it heads towards first quarter on Tuesday, September 14th, about the time it sets in the southwest, after which it waxes in its gibbous phase. You may be able to spot the slim crescent the evening of Friday the 10th as it glides beneath Mars and the star Spica (Mars the fainter of the two), with Venus up and to the left of the Moon. Then the night of Saturday the 11th, it will shine nicely to the other side of the bright planet, the two having switched places. Look early in twilight. The waxing crescent then meets up with Antares in Scorpius, seen closely to the west of the star the evening of Monday the 13th, but well to the other side the following night. The Moon actually passes directly over Venus on Saturday the 11th, but during the day and out of sight for North Americans.

We speak of looking at Mars, but it's now a tough find, though Venus is readily still visible in twilight. Indeed, it's still brightening as it closes in on Earth, and will until the 23rd. Sadly, we are in an unfortunate position in that the tilt of the solar path -- the ecliptic -- which the planets pretty much follow as well, lays rather flat against the horizon, which keeps Venus very low after darkness begins to fall.

But not Jupiter, which now dominates the later evening sky, the planet rising around 7:30 PM Daylight Time, before the end of twilight and Venus-set. By 1:30 AM it is crossing the meridian to the south, then remains up in the southwest the rest of the night. The planet's main moons can be seen in steadily-held binoculars. Though the giant of the planetary system, Jupiter still carries but a thousandth the mass of the Sun. Slowly moving retrograde (westerly against the stars), the planet is gliding just a degree or two south of the Vernal Equinox in western Pisces.

In other hot planetary news, Mercury becomes visible in eastern morning twilight below Regulus, while very dim Pluto, in Sagittarius, ceases its backward movement and begins direct easterly motion on Monday the 13th. Not that you'd much notice, as the little "ex-planet" moves only a bit over a degree per year. But it makes a good time to celebrate the life of its discoverer, Clyde Tombaugh.

As the Dipper rolls down the northwestern sky, its opposite, Cassiopeia, the Queen of the Perseus myth, rises in the northeast, the constellation easily distinguished by its famous "W" shape. Behind it follow Perseus itself and the rest of the gang, dim Cepheus (who is pretty out of the myth himself) in the lead.

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