SKYLIGHTS

Astronomy news for the week starting Friday, March 31, 2000.

At the beginning of the week, the Moon wanes in the early morning sky toward new, that phase reached around noon on Tuesday, April 4, the Moon of course then totally invisible. During the week, it will pass every planet of the Solar System except Neptune and Pluto, as they gather together around the central Sun. On Friday the 31st, the waning crescent passes south of Uranus, on Saturday April 2 to the south of Mercury, then on Monday, the 3rd, to the south of Venus. None of these passages are visible, however, because of proximity to the Sun; Venus in fact is now effectively gone from our skies.

The evening is a different matter. Deep in the west after sundown, Saturn, Jupiter (the brightest), and Mars descend in a line tilted down and to the right toward the horizon. The Moon will progressively pass south of Mars, Jupiter, then Saturn during the day of Thursday, April 6. By Thursday evening, the now-waxing crescent will be nicely visible (the lunar night lit with Earthlight) to the left of Saturn. That same night, Mars and Jupiter can be seen in close conjunction, much dimmer Mars (use binoculars) just up and the right of huge Jupiter.

All the naked-eye planets will then continue to close on one another as they draw toward a packed grouping next month. Though predictions of dire events may surface in the press, the "alignment" (such as it is) will have no effect whatever on the Earth. Such groupings commonly come and go and make no more than an attractive sight, though this one will be well-hidden by the Sun.

Directly above Saturn in the early-evening western sky is that most famed of star clusters, the Pleiades, or Seven Sisters, now escaping the spring skies toward the west. Binoculars will show many more stars. At a distance of 410 light years (26 million times the distance between the Earth and the Sun), the starlight you see left the cluster in the year 1590, a half-century after Copernicus finally placed the Sun at the center of the Solar System, and 20 years before Galileo made his first telescopic observations of the heavens. Light travel time is ordinarily of little consequence in astronomy, however, as the stars live so long, those of the Pleiades born some 100 million years ago. As Orion and the Pleiades sink slowly toward western twilight, look opposite to see the epitome of spring stars, orange Arcturus, rising in the east. Much closer than the stars of the Pleiades, its light left only 37 years ago, in 1963. In the northeastern evening sky the Big Dipper stands on its handle, crossing nearly overhead in the continental US around 11 PM.