Skylights featured on Astronomy Picture of the Day

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


Photo of the Week. Sunrise glory.

Astronomy news for the two-week period starting Friday, September 15, 2006.

Our fortnight fits between the two lunar quarters. Beginning with third quarter on Thursday the 14th, the Moon slims in its waning crescent phase to new on Friday the 22nd, then fattens in the waxing crescent to first quarter on Saturday the 30th. Note that the dawn waning crescent faces down and to the left, while the evening twilight waxing crescent faces down and to the right, in both cases toward the invisible Sun. The morning of Monday the 18th, the Moon will rise almost directly above Saturn, while the following morning it will be down and to the left of the ringed planet and directly above Regulus in Leo. During the second week of our period, watch the crescent climb toward Jupiter. The night of Monday the 25th, the Moon will be to the southwest of the giant planet, while the following night it will have flipped to the other side. Then admire the near-quarter just to the west of Antares in Scorpius the evening of Wednesday the 27th.

In the middle, the new Moon will eclipse the Sun, though unfortunately not as seen from North America. Indeed, plowing right down the middle of the south Atlantic Ocean, the eclipse path seems to avoid almost all land masses. No matter. The Moon is near apogee, so the eclipse is "annular," that is, the Moon cannot completely cover the solar disk, allowing a bright ring of sunlight to be seen, making the event scientifically far less interesting.

It is the Earth that takes center stage, as at 11:03 PM Central Daylight Time on the night of Friday the 22nd (12:03 AM EDT Saturday the 23rd, 10:03 MST back on the 22nd, 9:03 PM PDT, 8:03 PM Alaska, 6:03 PM Hawaii), the Sun crosses the autumnal equinox in Virgo and astronomical fall begins in the northern hemisphere. On the night of the 22nd, the Sun will set very close to the west point of the horizon, while the morning of the 23rd it will rise very close to due east. At equinox crossing it glides overhead at the equator, while technically setting at the north pole and rising at the south pole (the actual dates respectively delayed and advanced by the Sun's half-degree angular diameter and upward refraction by the Earth's atmosphere).

The only bright planets to admire now are the two largest. But don't look too late to find Jupiter, as it sets around 9 PM. Then comes a long gap until Saturn rises around 3:30 AM. For all practical purposes, Venus is lost to morning twilight.

In early evenings, Sagittarius rides low above the southern horizon. The Archer holds two beloved asterisms (small informal constellations), the Teapot (its "tea" the glorious Milky Way) and the upside-down five-star Little Milk Dipper. Dipper figures abound in the sky. In the far north are both the Big and Little Dippers of Ursa Major and Minor, while the brighter stars of the Taurus's Pleiades star cluster make another fine, though much smaller, one.
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