Astronomy news for the week starting Friday, August 24, 2001.

The Moon passes through its first quarter early in the week, on Saturday, the 25th, thereafter waxing toward its full phase, brightening as it goes through Scorpius and Sagittarius, bottoming out at its most southerly position of the month the night of Tuesday, the 28th. The night of Saturday, the 25th, the Moon will pass 12 degrees north of Antares in Scorpius, while the following night it will be approaching its passage to the north of Mars. The night of Thursday the 30th, it is Neptune's turn to be visited.

Mars is now transiting the meridian to the south in bright twilight; by darkness it has moved into the southwest, where, as seen in the early evening, it will remain throughout the year. For observers in the mid-northern hemisphere, setting time has moved to just after midnight daylight time. But as Mars prepares to set, Saturn rises in the northeast, followed around 2 AM by Jupiter, which has now pulled rather far to the west of Venus, the brilliant "morning star" rising before the onset of twilight until the end of October (by which time Saturn and Jupiter will be rising in early- to-mid evening).

Not that anyone will notice, but Pluto ceases its westerly retrograde movement against the stars of southern Ophiuchus this week, on Saturday the 25th. Three days later, Ceres, the largest asteroid (570 miles -- 910 kilometers -- wide and also invisible without a telescope), does the same thing. The orbits of asteroids are commonly more highly tilted than are those of the planets (Pluto excepted). Ceres, now beneath the Little Milk Dipper in Sagittarius, is about as far south as it gets, some 8 degrees below the ecliptic (the apparent path of the Sun).

As August heads towards September, the sky's fifth brightest star, Vega in Lyra, passes nearly overhead in early evening for those in mid-northern latitudes. A bit farther north (and a bit west) is the much fainter head of Draco, the Dragon. A line drawn south from Vega passes through the line of stars that makes the tail of Serpens the Serpent (the only constellation that comes in two parts, the head and tail divided by Ophiuchus), then much farther down back to Sagittarius, which sits atop Corona Australis, the Southern Crown. Once the Moon gets out of the way, you can admire the great star clouds of the Milky Way that seem to blanket Sagittarius, the celestial archer, one of two mythological centaurs in the sky, the other Centaurus, a much larger constellation now escaping to the west, its southern portions far below the horizon for most people in the northern hemisphere.
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