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Photo of the Week.. Strong "supernumerary bows," caused by the interference of light inside raindrops, lie beneath the primary rainbow.

Astronomy news for the week starting Friday, February 8, 2002.

The early part of the week belongs to the waning crescent Moon, as it heads toward its new phase, which will be reached on Tuesday, the 12th. You will see the beginning waxing crescent, beautifully illuminated by earthlight, the night of Wednesday the 13th in western twilight. Enjoy the sight.

The planetary news belongs mostly to Saturn. Both it and Jupiter now dominate the evening sky. Saturn, beautifully set just north of the jewel-like Hyades in Taurus and to the south of the even-prettier Pleiades, crosses the meridian to the south around 7 PM, while much brighter Jupiter (the brightest body in the night sky after the Moon), in western Gemini, makes the same passage around 9 PM. As the pair slip ever-farther into the western sky, their retrograde, westerly, relative motion against the background stars slows. On Friday the 8th, Saturn's comes to a complete halt. From now on until we make our next passage between the planet and the Sun, Saturn will return to its normal easterly motion, and begin to move away from its current partnership with the Hyades. Jupiter will follow suit in three weeks.

Farther out from Saturn lie the two smaller and more mysterious planets Uranus and Neptune. Both in Capricornus, Neptune (to the west of Uranus) passed conjunction with (far to the other side of) the Sun a couple weeks ago, and now it is Uranus's turn, the alignment taking place Wednesday, the 13th. In the other direction, the asteroid Juno is in opposition to the Sun. Though, with a 150-mile diameter ranking thirteenth in size, it was the third asteroid to be found nearly 200 years ago, and among the largest 15 asteroids after Vesta (the only asteroid visible to the naked eye) the second-most reflective. The asteroids, countless numbers of them lying between the orbits of Mars (still easily seen in the west in early evening) and Jupiter, remind us of the power of giant Jupiter, whose gravity has kept them so stirred up that instead of combining to form a planet, their violent collisions just keep grinding them down.

The lack of bright moonlight now brings out the brilliant winter stars. Orion crosses the meridian about 8 PM, Canis Major with Sirius following about an hour later. If you have a particularly dark sky, you can see the faint glow of the winter Milky Way sliding down from Taurus and Auriga to the left of mighty Orion and then past the Great Dog. Our Sun is set rather well off to the edge of the disk that makes our Galaxy and the Milky Way. At this season, in the evening we face away from the center, and the Milky Way becomes soft and subtle, less grand than the summer version, but in its way no less beautiful.
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