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

Sunshine through clouds

Photo of the Week. Given any chance at all, the Sun will shine through the darkest of clouds. (See a broader view.)

Astronomy news for the week starting Friday, June 16, 2006.

Skylights' "Picture of the Week" for February 24 was recently featured on the Earth Science Picture of the Day .

We begin our week with the Moon in its waning gibbous phase just shy of third quarter, that phase reached on Sunday, June 18. Bracketed between Uranus and Venus, the Moon passes Uranus on Saturday the 17th. After the quarter, it then wanes in its crescent phase through the end of the week (Friday the 23rd), when it will be seen to the northeast of Venus (which rises as dawn begins), the duo presenting us with a pretty sight.

Two big events mark the week. The first involves us and the Sun, as the latter crosses the Summer Solstice near the Taurus-Gemini border at 7:26 AM CDT (8:26 EDT, 6:26 MDT, 5:26 PDT, earlier in Hawaii and Alaska) on Wednesday, June 21, marking the beginning of astronomical summer in the northern hemisphere. At that time, the northern axis of the Earth will lean directly toward the Sun (tilted through its 23.4 degree angle relative to the orbital perpendicular), the Sun will be overhead at the Tropic of Cancer (23.4 degrees north latitude), and will be circumpolar (not setting) at and above the Arctic Circle (66.6 degrees north, though because of atmospheric refraction and finite angular solar diameter, a bit to the south of the Circle).

The other event is a lovely conjunction between Mars and Saturn. Mars has been moving up on Saturn for weeks now, and on Saturday the 17th will pass just 0.6 degrees to the north of the ringed planet. Look low to the west just after dark, as the pair will set around 11 PM. Then watch in subsequent nights as Mars, moving quickly toward the east, leaves Saturn behind. Though the two will look to be physically close, the pairing is only a line-of-sight effect, as Saturn will be 4.3 times farther away (Mars 2.3 times farther from the Sun than we are, Saturn 9.8). In spite of being farther, Saturn (at zeroth magnitude) is 3.6 times the brighter (Mars, reddish and at second magnitude) because it is so much larger and has bright reflective rings. At the same time, the Beehive Cluster in Cancer will be but half a degree away to the north, the "trio" making a unique and wonderful sight in binoculars.

In lesser news, Mercury hits its greatest eastern elongation on Tuesday the 20th, making it nicely visible in northwestern evening twilight. That same day, it passes six degrees south of Pollux in Gemini. With Uranus beginning retrograde (westerly) motion on Monday the 19th, only Jupiter is left to go, the giant planet crossing the meridian to the south in mid-twilight, then setting around 3 AM, about an hour before Venus rises.

We are beautifully into Bootes season, when the Herdsman rides high and nearly overhead around 9 PM along with its shining luminary, Arcturus, the fourth brightest star in the sky and the brightest of the northern hemisphere (just edging out Lyra's Vega). Down below is Spica in Virgo, and far below Spica lies vast Centaurus (whose southern reaches hold the closest and third brightest star, Alpha Centauri, which is out of reach for all in the US except those in the very far south).
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