Fall arrives Tuesday, and the sky throws a party around it: Saturn all night, a hidden planet at its best, aurora season and a Harvest Moon to close the week.
The equinox hits Tuesday, Sept. 22 at 8:05 p.m. ET (5:05 p.m. PT). The Sun crosses the equator heading south, and nights start outlasting days.
Saturday, Sept. 19 is NASA's Observe the Moon Night. The waxing Moon sits in Sagittarius in the south after dark and sets just after midnight in New York.
Saturn rises in the east around sunset and shines all night, brighter than any star near it. It reaches opposition Oct. 4, and a small telescope shows the rings.
Neptune hits opposition Friday, Sept. 25 at 9:28 p.m. ET (6:28 p.m. PT). It is too faint for your eyes, but binoculars find it about 9 degrees from Saturn.
Geomagnetic storms are more common around the equinoxes, when Earth's tilt lets the solar wind couple more easily with our magnetic field. Late September is prime time.
NOAA's Space Weather Prediction Center posts a free 30-minute aurora forecast. If it lights up over the northern U.S., head somewhere dark and look north.
Fall mornings are the best time to see zodiacal light, sunlight bouncing off space dust. Look east from a dark site before dawn; the Moon sets by 2:15 a.m. through Sept. 22.
The Harvest Moon, the full Moon nearest the equinox, peaks Saturday, Sept. 26 at 12:49 p.m. ET (9:49 a.m. PT). Watch it rise that evening with Saturn nearby.
Near the equinox, moonrise comes only about 25 minutes later each night. In New York it rises 6:12, 6:35 and 6:59 p.m. from Sept. 25 to 27: bright light at dusk for days.
Moon tonight, equinox Tuesday, Neptune Friday, Harvest Moon Saturday, Saturn every night. All you need is a clear sky and a pair of binoculars.