Astronomy news for the week starting Friday, April 2, 1999.

The Moon, having passed full, is in its waning gibbous phase this week, rising ever later and passing third quarter the night of Thursday April 8. Since the Sun recently passed the vernal equinox, this third quarter, three quarters of the way around the sky from the Sun, will be just past the winter solstice in Sagittarius. Because it will be so far to the south, it will be the latest-rising third quarter moon of the year, not coming up above the horizon until around 1:30 AM standard time (2:30 AM daylight time) the morning of Friday, April 9. Tonight, the night of Friday, April 2, the Moon will pass to the north of Mars, making the red planet easy to find, the closest approach taking place around 3 AM on the morning Saturday, April 3.

Mars continues brightening as it plies its retrograde path on the Libra-Virgo border to the east of the star Spica, which it now far outshines. It will reach maximum brightness toward the end of April as it passes opposition with the Sun. Rising in the southeast around 9:30 PM, Mars is now in the sky with its opposite, Venus, which sets in the northwest an hour later, Saturn now setting much earlier, at the end of twilight. Mars and Venus will continue to approach each other, Venus setting later, Mars rising earlier, until early summer. However, they will not cross apparent paths to come into conjunction, as Venus will then quickly be overtaken by the Sun, while Mars will linger in the evening throughout this year and into the year 2000.

Reddish Mars, and Venus, a pale yellow-white, contrast more than in color. Venus, covered with a thick carbon dioxide atmosphere 100 times the pressure of Earth's, and sulfuric acid clouds, is terribly hot, 470 degrees C (870 degrees F). Mars, with a thin atmosphere only 1/100 Earth's pressure, is cold enough to have polar caps and "snow" of frozen carbon dioxide (dry ice). Compared to Venus, however, Mars is inviting, and will almost certainly be visited by astronauts sometime in the next century.

The constellations of spring are now in full bloom, great Leo of the zodiac with the bright star Regulus crossing to the south around 10:30 PM daylight time. High above, nearly overhead is the most famed of northern figures, the Big Dipper of Ursa Major, the Great Bear. South of the Dipper try to find a large patch of faint stars, the lovely sprawling cluster that makes the entire constellation of Coma Berenices, Berenices Hair, honoring an ancient Egyptian queen.
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