Astronomy news for the week starting Friday, April 28, 2000.

The next Skylights will appear on Sunday, May 7. The crescent Moon wanes toward new early in the week, the phase reached the night of Wednesday, May 3. A day later, the evening Thursday May 4, the slim waxing crescent will pass some 5 degrees south of Mars. Though the Moon will be barely visible in bright twilight, Mars, far away and relatively faint, will be very difficult to find. While the crescent waxes, it passes perigee (its closest point to the Earth) on Saturday, May 6.

The "ancient" planets, those known since humans have walked the Earth, continue to gather together, Mars, Jupiter and Saturn still to the east of the Sun, Mercury and Venus to the west of it. This week all the ancient 7 "moving bodies" of the sky -- the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn -- will be in their closest congregation, a highly unusual occurrence, and one unfortunately unobservable because of the brilliance of the Sun. The Sun, of course, does not really move against the stellar background, but only appears to do so because of the movement of the Earth. With some exceptions in ancient Greece, the truth was not understood until Copernicus "placed" the Sun at the center of the Solar System.

The sky is brought to Earth in many ways. These seven bodies, plus the seven days of the quartering of the Moon's phases, are responsible for our 7-day week; the 29.5-day period of the lunar phases (stretched a bit to fit the year) made our 30-31 day months; and the 365-day year created the 360 degrees of the circle (360 a wonderful number that can be divided by a host of others). As a result, the Earth goes around the Sun almost one degree of its orbit per day, the Sun appears to move along the ecliptic (its apparent path) by almost one degree per day, and at night the stars (if viewed at the same time) seem to slip to the west daily by the same amount.

This week hosts one of the better meteor showers of the year, the "Eta Aquarids." With the Moon out of the sky, an observer on the morning of Friday, May 5, may witness as many as 30 meteors per hour pouring from the constellation Aquarius. (The best place to look, however, is overhead.) Meteors are caused by small interplanetary rocks hitting and heating up in the Earth's atmosphere. Almost all meteors come from the debris flaked from comets as they disintegrate under the heat of the Sun. The Eta Aquarids are seen as we pass near the orbit of Halley's Comet, which tours the Sun every 76 years. In October, when we pass close to the other side of the orbit, Halley's debris produces the Orionid shower.
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