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Midnight Sun

Photo of the Week. The midnight Sun shines over Lake Colleen at Deadhorse (Prudhoe Bay), Alaska, on July 7, 2007. The Sun is still so far north that it stays up for 24 hours a day, which is possible only above the Arctic Circle. It will finally set later in the month as it moves to the south. A latitude here of 70.2 degreees north gives an actual solar (center) elevation of 2.9 degrees, which is raised to 3.0 degrees by atmospheric refraction.

Astronomy news for the week starting Friday, July 27, 2007.

'Tis the week of the full Moon, the bright orb blanking out all the fainter stars. Formal full is passed the night of Sunday, July 29, roughly about the time of Moonrise in North America. The full Moon (directly opposite the Sun) thus rises in the southeast just as the Sun sets. With the Sun firmly ensconced in Cancer, the full Moon will be found passing through Capricornus, its dim stars quite invisible to the eye. It then spends the remainder of the week in its waning gibbous phase as it heads toward third quarter on Sunday, August 5. As it travels, the Moon passes south of Neptune on Monday, July 30, and then south of Uranus on Wednesday, August 1. Slowly moving Neptune is still near the Capricornus-Aquarius border, while Uranus is just south of the Circlet of Pisces.

Venus and Saturn, travelling more or less together (as projected onto the sky, not in reality), are both now effectively gone from sight (though a dedicated observer might still catch very bright Venus very low above the western twilight horizon). On the other side of the sky and the night, Mercury is making one of its better (though still difficult) appearances in eastern morning twilight, Castor and Pollux in Gemini more or less pointing downward at it. The little planet passes six degrees south of Pollux on Wednesday, August 1. That leaves the night pretty much to Jupiter and Mars. Jupiter, in southern Ophiuchus (the modern boundaries of which cross the ecliptic) to the east of Antares in Scorpius, transits the meridian in early evening twilight and then spends the rest of the night in the southwestern sky until it sets around 1:30 AM Daylight Time. Reddish Mars, rising just before local midnight (1 AM Daylight) just a bit before Jupiter's disappearance, then takes over the morning in a lovely setting at the Taurus-Aries border to the southwest of the Pleiades and to the west of the Hyades cluster.

The Big Dipper, the great iconic asterism of Ursa Major, has for some time now dominated the evening zenith sky. As summer passes its midpoint, we see it now slipping into the northwest, most of the figure of the Great Bear to the south and west of it. Look opposite the Dipper into the northeast to find the "W" of Cassiopeia rising, telling us that summer will before long turn to the colors of fall.
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