Astronomy news for the week starting Friday, October 9, 1998.

The Moon runs through its third quarter this week, passing the phase on Monday the 12th just about the time of sunrise as the Moon is crossing the celestial meridian to the south. With the Sun not far to the east of the autumnal equinox in Virgo, the third quarter, which is 90 degrees to the west of the Sun, will appear close to the summer solstice in Gemini, the constellation's bright stars making a nice setting to the west of the Moon. During the rest of the week, the Moon descends in early morning hours toward the eastern horizon as a waning crescent. On the morning of Thursday the 15th, the crescent will be to the west of Mars and close to the bright star Regulus in Leo, the next morning to the east of the red planet.

Early risers can see Mars zipping quickly to the east against the stars of central Leo as it continues ahead of us on its orbital path. Mars's reddish color is caused by iron oxide in the dust that covers much of the planet. The dust is so fine it can get kicked up by wind storms in the thin atmosphere and for a time can hide surface details from view. No rain is associated with the storms as the planet is very dry, only a tiny amount of water vapor in the atmosphere.

Those who do not rise early can admire brilliant Jupiter climbing the southeastern sky after sundown. There we find no dust at all, the telescope showing nothing but perpetual banks of clouds laid out in a striped pattern and made largely of ammonia crystals. It and the next planet to rise, Saturn, which is not far to the east of Jupiter, are thought to be made mostly of liquid hydrogen buried far below their deep gaseous atmospheres.

As we move deeper into autumn, look for the W-shape figure of Cassiopeia climbing the northeastern sky, circling the pole opposite the Big Dipper. To the east, find the Pleiades star cluster -- the famed Seven Sisters of Greek mythology, daughters of Atlas -- rising above the Vee-shaped head of Taurus, made by the stars of the Hyades cluster. The Pleiades auger the coming of Orion and the constellations of winter. They are famed in all cultures. For the Inca of Peru they were a harvest basket, to the Polynesians "little eyes," to the Navaho, who called them "Dilyehe," they were dancers or warriors. To these and others they were -- and still are -- a celestial timepiece that tell the passing of the hours and the seasons.
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