Skylights featured on Astronomy Picture of the Day

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

Canis Major

Photo of the Week. Canis Major, Orion's Greater Hunting Dog, bounds through the forested sky, its great star Sirius sending out a mighty glow.

Astronomy news for the week starting Friday, March 10, 2006.

Read A Minute with Jim Kaler, a brief interview on the outer bodies of the Solar System that appears on the U of I home page.

We begin the week with the Moon in its waxing gibbous phase moving toward full, which it will reach the night of Tuesday, March 14, about the time of Moonrise in North America - - or, since the full Moon is opposite the Sun, also about the time of sunset. The night of Friday the 10th finds the Moon to the northeast of Saturn; the night of Saturday the 11th it will be to the west of Regulus, the star at the end of the "Sickle" of Leo. On the night of the full phase, the Moon will appear south of Denebola (also in Leo) as it enters western Virgo rather well to the west of Spica, which (in the waning gibbous phase) it will pass the morning of Friday the 17th (and will actually occult for those living in Hawaii).

Two days before full, the Moon will pass apogee, where it is farthest from the Earth in its monthly round. The full Moon actually rises in North America during the ending stage of a penumbral eclipse, in which the Moon is passing out of the penumbra of the Earth's shadow. The penumbra is the region of partial shadow; were one on the Moon, one would see the Earth only partially blocking the Sun. Do not confuse with a "partial eclipse" in which part of the Moon enters the full shadow of the Earth. Penumbral eclipses are barely visible, and this one for us will not be sensible at all, so just admire the Moonrise.

Mercury is now completely gone from the visible sky, as it passes inferior conjunction with the Sun (more or less between us and the Sun) on Saturday the 11th. Saturn, still in Cancer, lies high to the south in mid-evening. Mars, moving quickly through Taurus, will pass seven degrees to the north of Aldebaran on Friday the 10th, giving us for several days a fine chance to compare similarly- colored celestial jewels, the red planet not setting until somewhat after midnight. Jupiter's southeasterly rise around 10:30 PM will then give us three planets to admire. The planetary giant then transits the meridian about 4 AM about as brilliant Venus rises and Saturn sets.

March is a fine time to pay attention to Orion's two hunting dogs, Canis Major and Canis Minor, which respectively lie to the southeast and east of Orion, and which are graced by two bright stars, Sirius (the brightest in the sky) and eighth-ranking Procyon. Curiously, the luminaries of the two dogs are both attended to by orbiting white dwarf stars, old dead nuclear-fusing cores that once far outshined their mates and that are now shrunk to the size of Earth. The two bright stars are connected as well through one of the great cross-constellation figures of the sky, as with Betelgeuse they make the Winter Triangle.
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