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.End of day.

Astronomy news for the week starting Friday, March 13, 2009.

The week begins with the Moon in its waning gibbous phase, which ends with the third quarter on Wednesday, March 18, about the time of Moonset in North America. We then get to see a bit of the waning crescent before Friday rolls around again. That the week has seven days is no surprise, as the weeks mark off the intervals between the lunar phases of the moment (new, full, the quarters). With the Sun nearly at the Vernal Equinox in Pisces, this third quarter will be the lowest of the year, falling just shy of the Winter Solstice, between the classical figures of Sagittarius and Scorpius.

The morning of Monday the 16th, the Moon will seen to the west of Scorpius's Antares (the two always making a fine sight), while the following morning they will be much closer, with the Moon now to the east of the star. The day after last quarter, on Thursday the 19th, the Moon then passes apogee, when it will be farthest from Earth.

Plunging toward the Sun, Venus is notably lower in the western sky, setting before 9 PM, and by 8:30 in twilight at the end of the week. The evening now more and more belongs to Saturn, which is already up in the east at sunset and crosses the meridian to the south just before midnight. The star close to it is fourth magnitude Sigma Leonis. In the morning sky, Jupiter glows in twilight close to the southeastern horizon.

Creeping slowly along the ecliptic at a degree per day, the Sun finally reaches the Vernal Equinox on the celestial equator the morning of Friday, March 20, about the time of sunrise in North America, allowing for a bit of morning celebration. Spring in the northern hemisphere formally begins at 6:44 AM Central Daylight Time (7:44 EDT, 4:44 PDT). On that day, the Sun will rise due east, set due west (rendering days and nights more or less equal), and be overhead at the Earth's equator. It also formally rises at the north pole and sets at the south pole, though refraction by the Earth's atmosphere and the finite diameter of the Sun advances the "rise" and delays the "set" by a bit.

Comet Lulin is both fading away and moving more slowly. This week it spends its time in central Gemini, passing just south of Delta Geminorum the middle of the week.

While we concentrate on the bright constellations, many are the faint ones. Look to the south of a line between Betelgeuse in Orion and Canis Minor's Procyon (to the left of Betelgeuse) and to the north of Canis Major's Sirius to find (if you can) the stars of Monoceros, the Unicorn.

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