We begin to preview winter skies on October evenings. After midnight, for example, Orion and all the stars associated with it are rising in the east. But even earlier at night there are two important signs. One is in the northeast, where the bright blue-white northern star, Capella, in the constellation Auriga, is well above the horizon even at sundown. Capella is far enough north to be almost circumpolar (never-setting). The other winter harbinger is Taurus, with its reddish star Aldebaran and the V-shaped stars of the Bull's face below it. Aldebaran is seen in the east easily by 9 p.m. in October.
Events in the following calendar are given in local time unless otherwise indicated.
Oct. 1: First-quarter moon is in Sagittarius, along with Mars and Jupiter. The bright planet is Jupiter, just above the moon, while Mars, now dimmer than it's been since February, is to their right. The stars of Sagittarius are below. Look for the ''teapot.''
Oct. 3-4: The gibbous moon, up at sunset and setting after midnight, is in Capricornus both nights.
Oct. 5-6-7: The moon spends three nights in Aquarius, fattening up for full moon in a few days. The star beneath it on the 6th is Fomalhaut, while the stars above belong to Pegasus.
Oct. 8: Apogee moon (farthest from Earth) is on Pisces' border with Cetus. Venus moves past Saturn, both above the horizon at sundown, well to the sun's left (about 2 hours), but very low. You might see Venus on a clear night, looking much like the landing lights of a low aircraft in the sunset glow. Saturn is much dimmer.
Oct. 9: The Hunter's full moon has been creeping up on us day by day, arriving at 6:58 p.m. Eastern standard time. It looks as though the moon has been on the horizon each night at sundown for the last several nights, rather than rising about an hour later nightly. As a matter of record, the moon rises only about 23 minutes later each night between Oct. 6 and 12. It is this characteristic that makes the Hunter's moon exceptional.
Oct. 13: The gibbous moon, now waning, is in Taurus, rising just after 7 p.m. Aldebaran is a reddish star below it, and the nebulous-like cluster above is The Pleiades. Try looking at The Pleiades stars with binoculars for the miniature dipper embedded in a cloud of dimmer stars. That was one of the remarkable discoveries Galileo made when he first looked through a telescope 375 years ago.
Oct. 16-17: The moon rises with Gemini well before midnight on both dates. Last-quarter phase is at 4:14 p.m. EST on the 17th, and the two stars in line above the moon later that night are Pollux and Castor, the ''twin'' stars.
Oct. 20: Leo's bright star Regulus is near the moon from 2 a.m. until dawn.
Oct. 21: The Orionid meteor shower, although certainly not the best of the year, has the advantage of the late crescent moon, ensuring darkness during the after-midnight hours best for viewing its swift, relatively bright meteors (about 25 per hour).
Oct. 23-24: The moon is at perigee (nearest earth) about 9 a.m. EST on the 23 rd, new at 7:08 a.m. EST on the 24th. The perigee effect will add to the normally strong fall tides that come after the new moon.
Oct. 26: One of those great planet-star scenes will be in the sky tonight, brilliant Venus standing just below the ''nether'' (lower) horn of the crescent moon. They are best seen in the Southern Hemisphere, where they're higher in the evening twilight, so you will need clear westerly skies to see them low in the sunset sky from mid-northerly latitudes. The moon is close enough to cover (an occultation) Venus over the Pacific. Saturn is close by to Venus's right, the ruddy star Antares (in Scorpius) below Venus.
Oct. 28-29: The crescent moon is in Sagittarius, along with Jupiter and Mars. It passes above Jupiter on Monday night, below Mars on Tuesday night.
Oct. 30-31: The moon closes out the month in Capricornus, reaching first-quarter phase at 8:07 a.m. EST on Wednesday.