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Photo of the Week. Total eclipse of the Moon, August 28, 2007. The reddish color of the Moon comes from light leaking into the shadow through the Earth's atmosphere. The upper part of the Moon is darker because it is closer to the shadow's center and also contains a dark lava plain called Oceanus Procellarum.

Astronomy news for the week starting Friday, September 14, 2007.

Our Moon waxes through its crescent phase early in the week, then passes first quarter on Wednesday, September 19, after which it continues to grow in the waxing gibbous. The evening of Monday the 17th, look for the crescent below Antares, with Jupiter topping the pair. The following night the Moon will appear to the left of Antares, these two and Jupiter now making a fine triangle. The day after our week begins, the crescent will pass apogee, where it is farthest from the Earth.

Ever so gradually, Jupiter shifts more and more to the southwest as seen in early evening, the giant planet now setting around 10:30 PM Daylight Time. Mercury is up in western twilight as well, but so low as to be difficult to find, and really requires binoculars. We do now, however, have Mars as an evening object, though a bit later, the red planet now rising in Taurus around 11:30 Daylight Time. Still moving easterly against the starry background, Mars now rides between the horns of the celestial Bull to the east of the Hyades cluster. It's on its way to Gemini, which it will reach about the end of the month, and does not enter retrograde until November 15. Finally, on December 24, it will pass opposition with the Sun. An hour of so after Mars rises, Uranus -- barely visible to the naked eye -- crosses the meridian to the south.

The morning sky is now graced by Venus , which rises just before 4 AM, over an hour before the onset of twilight and the hard-to-see rising of Saturn. Venus will continue to get brighter until next week, and will -- still brilliant -- continue to get higher in the sky well into October.

The Sun is moving about as rapidly as it ever does to the south in preparation for its passage of the autumnal equinox next week, the points of sunrise and sunset moving ever closer to the east and west points of the horizon.

This is a fine time of year to view the Summer Triangle, made of three white stars. Vega in Lyra lies at the northwestern apex, Deneb in Cygnus lies at the northeastern point, and Altair in Aquila marks the southern extension. Such triangles seem to draw the eye. A few months from now we can admire the Winter Triangle made of Betelgeuse (Orion), Sirius (Canis Major), and Procyon (Canis Minor). These two are large informal "asterisms." Others, autumn's Triangulum and the deep south's Triangulum Australe, are formal constellations, the first from ancient times, the second one modern, invented only a few centuries ago.
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