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

Moon and Venus

Photo of the Week. A 3.3-day-old crescent Moon, its nighttime side glowing faintly with Earthlight, visits Venus.

Astronomy news for the week starting Friday, August 20, 2010.

The Moon continues to grow the early part of the week within its waxing gibbous phase until it hits full on Tuesday, August 24th, around noon in North America, rendering it just past the phase when it rises that evening just after sunset. The remainder of the week sees it moving through the early part of the waning gibbous as it heads for third quarter next week. Just half a day past full, the Moon goes through apogee, where it is at its farthest orbital point from Earth, rendering the usual full-Moon high and low tides not quite so high and low.

Just five hours BEFORE full phase the Moon passes above Neptune, the planet starting the week in opposition to the Sun. Much more interesting is the lunar passage seven degrees north of Jupiter the morning of Friday the 27th (when it will also pass north of Uranus, the two planets quite close in angular pairing if not in distance, Uranus almost five times farther from Earth than is Jupiter).

About all that is still readily visible of the great summer western evening planetary line-up is brilliant Venus, and even that is getting rather low, the planet's setting now tracking the end of evening twilight. But be sure to try to catch the classic conjunction of Venus and Mars the evening of Monday the 23rd, the red one two degrees north of the bright one. You'll really need binoculars, as Venus will be some 100 times brighter than Mars, the result of differing distances from the Sun and Earth, as well as in surface reflectivity. Watch during this and next week as the two approach Spica in Virgo. Saturn, setting before twilight ends, will be to the right. Once they are gone, we look due east to see the rising of bright Jupiter. With us the rest of the night, Jupiter transits the meridian to the south around 3 AM Daylight Time.

By mid evening the Big Dipper is now sinking into northwestern skies, its three-star handle (the oddly-long tail of Ursa Major, the larger Bear) still quite prominent even from modestly bright locations. Follow its curve southward to Arcturus and then to Spica. At the same time, the bowl of the Little Dipper of Ursa Minor (the smaller Bear) rides high above and to the left of Polaris, which maintains its position above the horizon at an angle equal to your latitude. Between the Little Dipper's bowl and the bright star Vega (nearly overhead) is the squarish head of Draco the Dragon, whose tail winds up between the two Dippers. As the evening gets later and the Big Dipper goes down, watch for the coming-up of W-shaped Cassiopeia as it climbs the northeastern sky, the two circling the pole opposite one another.
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