September Sky Chart. Northern Hemisphere gazer's guide

The sky chart is designed to correspond to the sky at 10 p.m. the first of the month, 9 p.m. in the middle of the month, and 8 p.m. at the end of the month standard time. All Month: Mars recovers quickly from the obscurity of its conjunction last month, climbing very nicely into the morning sky before sunrise. By midmonth it joins Venus and the star Regulus (in Leo) as an interesting threesome in the dawn. Venus is the obvious leader in brightness, Mars the laggard and lowest in the dawn sky of the three. Venus also benefits materially by the northerly slope of its orbit relative to where the sun is. The planet scene is clearly shifting away from the evening sky in September. If it weren't for Jupiter, it would be rather poor. The only competition is from Saturn, not particularly distinguished in appearance, setting soon after darkness. Jupiter is something else. It begins to appear near the south after dark and remains in the sky till well after midnight. Mercury is still a prospective evening star in early March, but fades into the sun's glow as it approaches superior conjunction.

(Events in the calendar below occur in local time unless indicated otherwise.)

Sept. 1: The moon is already 21/2 days past full, yet moonrise is only about an hour after sunset. It's the ``harvest moon'' effect displaced a bit. Moonlight lasts virtually from dark till dawn tonight. You will find the moon near two celestial marine vertebrates tonight, Pisces and Cetus!

Sept. 2-3: Waning still, the moon moves through Pisces into Aries.

Sept. 4: Mercury almost covers Mars when passing below it tonight. Unfortunately, they are located where we can't see them, up only in daylight. The moon is at apogee, farthest from earth.

Sept. 5: The moon is near the Pleiades when it comes up tonight after 9 p.m.

Sept. 6-7: The waning moon passes above the Hyades, the V-shaped star cluster at the face of Taurus, the Bull. The bright red star at the apex of the ``V'' is Aldebaran. Last quarter moon is at 7:10 a.m. on the 7th.

Sept. 10: The morning moon is in Gemini, nearly in line with and below its twin stars Pollux and Castor. Much brighter Venus is below to the left.

Sept. 12: Venus and the old moon are a pretty sight this morning about dawn. We won't see the moon again until it passes the sun and emerges to its left as an evening crescent.

Sept. 14: New Moon, at 2:20 p.m. Eastern standard time (EST), is moving across the border between Leo and Virgo, along with the sun.

Sept. 16: Now two days past new, the perigee moon (nearest earth) could show up in Virgo tonight, just above the bright star Spica.

Sept. 18: Saturn rides the sky with the crescent moon tonight, drifting slowly to the left beneath it.

Sept. 19: The moon has just left Libra behind, along with Saturn. The lunar companion tonight is Antares, in Scorpius.

Sept. 21: Regulus is very near Venus this morning, passing it a moon's distance away at noon EST. The moon is snugly in Sagittarius, one of the zodiacal constellations, when it is first quarter at 11:03 a.m. EST.

Sept. 22: The sun crosses the equator in Virgo at 9:08 p.m. EST, and autumn begins in the Northern Hemisphere. Most years autumn starts on Sept. 23, but the ``breaks of the game'' we play with Leap Year cause it to vary. Mercury is in superior conjunction, entering the evening sky.

Sept. 23: Jupiter is moving slowly to the right through Capricornus (retrograding), while the moon is moving to the left just to its south. The effect is obvious tonight as the moon drifts toward, then past, Jupiter at 1 a.m. EST (on the 24th).

Sept. 24-27: The gibbous moon fattens up nightly as it slips through Capricornus, Aquarius, and Pisces en route toward the Vernal Equinox.

Sept. 27: The equinox was some days ago, but it's today that the interval between sunrise and sunset is exactly 12 hours. Of course, it is light for even longer than 12 hours if you include twilight.

Sept. 28-30: Full Moon on the 28th at 7:08 p.m. EST is the Harvest Moon because this one is so close to the Vernal Equinox. Because moonrise occurs so close to sunset for the next several days, it appears as if we have a full moon right to the end of the month. Dr. Thomas D. Nicholson, Director, the American Museum of Natural History, New York