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 .

fuzzy cloud

Photo of the Week.. Fuzzy clouds accent a deep blue sky.

Astronomy news for the week starting Friday, August 20, 2004.

The Moon begins the week just shy of its first quarter, the phase reached on Monday the 23rd, at which time the Moon will be 90 degrees to the east of the Sun, rise close to noon, cross the meridian as the Sun goes down, and set near midnight. Four days later, the Moon passes perigee, where it is closest to the Earth. Given that the Sun is about two- thirds of the way between the Summer Solstice and the Autumnal Equinox, the first quarter will be the same fraction between the Autumnal Equinox and the Winter Solstice, and will appear to the west of the classic figure of Scorpius, the Scorpion, one of the most prominent figures of the summer sky.

With the ancient planets clustered fairly close to the Sun, there is little in between except the most distant of them, Uranus, Neptune, and Pluto. Uranus, in Aquarius, goes through opposition on Friday, the 27th, so it is in prime viewing condition -- if you can find it. It lies almost directly below the center star of Aquarius's Water Jar, just to the west of 5th magnitude Sigma Aquarii. At the bright end of sixth magnitude, Uranus is visible to the naked eye if conditions are good; binoculars are much better. Good luck! Neptune is in eastern Capricornus, and for a real challenge -- if you have a large telescope (or not, it will still be there) -- Pluto is in southern Ophiuchus just to the northeast of Sabik (Eta Ophiuchi).

Wait until morning and you can see much brighter planets as Venus and Saturn (both in Gemini) rise almost together around 3 AM, Venus beating the ringed planet by roughly half an hour. Venus's great brightness makes it obvious almost upon rising. Saturn, over 60 times fainter than Venus, does not become visible until it is a fair way up. Entirely invisible, Mercury goes through inferior conjunction with the Sun (when it is more or less between us and the Sun) on Monday, the 23rd. Jupiter is, for now, effectively gone.

As twilight ends, look to the south to find the Little Milk Dipper of Sagittarius. If your horizon is flat and clear, you might spot the graceful curve of Corona Australis, the Southern Crown, directly below it. To the right of Sagittarius, Scorpius is beginning to escape to the west. Note the middle of the trio that makes the Scorpion's head, Dschubba (Delta), which has brightened notably almost to first magnitude as it mildly erupted and tossed off a surrounding shell of gas. The stars are not quite as constant as they might seem. Then of course admire the great red supergiant Antares, which will most likely explode sometime in the distant future. Above Scorpius are Ophiuchus, the Serpent Bearer, and the great Serpent (Serpens) that he holds, the figure bridging the gap between the Scorpion and Hercules to the north.
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