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Photo of the Week. Reflections.

Astronomy news for the week starting Friday, February 18, 2011.

With the full lunar phase being passed the morning of Friday, February 18, the vast bulk of the week is spent with it in the waning gibbous phase, third quarter not reached until the evening of Thursday the 24th. The night of Friday the 18th, the Moon goes through its perigee, where it is 5 to 6 percent closer to us than average.

As it traces out its perpetual path, the Moon will make a fine sight as it passes beneath Saturn the night of Sunday the 20th (actually the morning of Monday the 21st), when the Moon, Saturn, and the star Spica will make a near-equilateral triangle, Saturn above the waning gibbous, Spica up and to the left. Then the morning of Friday the 25th, look for the third quarter next to reddish Antares of Scorpius.

For a long time now, Jupiter has ruled the evening skies. But, now setting a bit after 8 PM, its dominance is fading away. Well within the hour, though, faithful Saturn rises to the northwest of Spica. By 3 AM it has passed the meridian to the south, it and Spica obvious a bit into the western skies by the time Venus lofts itself up over the southeastern horizon around 4:30 AM, a good half hour before dawn begins to light the sky. Look for it well up in the southeastern sky in bright twilight, by which time the stars will have faded away. Venus's inner partner, Mercury, though, is quite gone, as it passes superior conjunction with the Sun (on the other side of the Sun) the morning of Friday the 25th.

Jupiter still more of less marks the Vernal (Spring, a nice thought) Equinox, which lies about 5 degrees to the south-southwest of the giant planet. Saturn, rather opposite Jupiter, does not do quite so well, standing some 15 degrees to the southeast of the Autumnal Equinox in Virgo, but is still useful as a locator. In between, and high in the sky in mid-evening we find the Summer Solstice in the northwestern corner of classical Gemini. But therein lies a problem, in that around 20 years ago, precession, the 26,000- year-wobble in the Earth's axis, moved the Solstice over the formal -- but artificial -- boundary with eastern Taurus, which now technically holds it. For now, though, because the Solstice is closer to the classical figure of Gemini than it is to that of Taurus, and for reasons of celestial symmetry, perhaps we can still let the Twins hold our first day of Summer.
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