July 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: The bright planets are divided between the morning and evening skies, with a little bias toward the morning. Venus and Jupiter are morning stars, Saturn and Mercury evening, and Mars is in transition from evening to morning during July. But the brightness of Venus and Jupiter easily wins the toss. During the evenings, when summertime constellations are up, Saturn is low in the south at sundown and sets in the southwest about an hour past midnight, in Libra, about midway between Virgo's Spica and Scorpius' Antares. Jupiter, on the other hand, is much brighter and more easily seen after it rises in the west about three hours past sunset. Still a morning star, it remains in the sky for the night, giving a nice balance to Venus in the dawn, well up in the east. Mercury gives a fair shot in the evening sky, but not its best. Look in the west-southwest in late twilight if the sunset sky is exceptionally clear, from about March 10 to 20.
(Events in the calendar below are given in Eastern standard time unless stated otherwise.)
July 1: Tonight's moon might look full, but it's half a day shy, and there are two ways you can tell: It rises half an hour before sunset, and one side (which one?) is a bit uneven. Tomorrow night (after full moon) the other side will look uneven.
July 2: Full moon comes at 7:08 a.m., and the moon rises 15 minutes after sunset.
July 3-4: The gibbous moon is in Capricornus, approaching Jupiter, to its left. It passes above the planet early in the evening of the 4th.
July 5: Earth's aphelion (farthest from the sun) occurs today, but the weather probably won't give you a clue! It does moderate our summer a bit, however.
July 6-7: The gibbous moon (rising after 10) is an easy guide to the Square of Pegasus and the star Fomalhaut tonight -- after midnight, when they rise high enough.
July 9: The last-quarter moon comes at 7:49 p.m. It rises in Pisces, close to midnight.
July 10-11: The waning moon, now in Aries, rises after midnight, reaching apogee (farthest from Earth) at 3 a.m. on the 11th.
July 13: Mercury is at its farthest distance to the sun's left (greatest easterly elongation) today. The planet may be seen low in the west during twilight for a week or so before and after the 13th, but it won't be easy.
July 13-14: The morning crescent moon joins Venus in the eastern sky, both rising before dawn. The moon slowly approaches Venus on Saturday morning, passing north of it on Sunday morning.
July 15: Venus is near its prime as a morning star as it majestically drifts past Aldebaran, the bright ruddy star of Taurus. A glimpse at the rising crescent moon below to their left may be the last before new moon.
July 17: The new moon, coming at 6:56 p.m., is near Gemini's border with Cancer. Mars is finally in conjunction with the sun!
July 19: The young crescent moon shows up tonight in Leo, right in front of the Lion's mouth. The conjunction of the moon with Mercury won't help much in finding the elusive planet, far south of the crescent.
July 20-23: Not much happening these days except the crescent moon fattening and drifting east slowly through Leo and Virgo. But it does wonders for a clear summer's evening. Try following nightly as the moon drifts away from Leo and Regulus in the west toward Spica, Virgo's bright star, high in the south.
July 23-24: The moon's motion brackets Spica as it shifts from the star's right to left. Then the crescent becomes the first-quarter moon at 6:39 p.m. on the 24th.
July 25: The moon, at perigee in Libra, passes Saturn below our horizon early on Friday morning.
July 26: Saturn ends its retrograde (westerly) drift through Libra, signaling the end of its sojourn as an evening star. Mercury, on the other hand, signals the end of its evening performance by beginning its retrograde motion today.
July 27: The reddish star to the moon's right is Antares in Scorpius.
July 28: Maximum of the broad, sparse, relatively slow and dim southern Eta Aquarid meteor shower is today. Not too great a display, but with the moon setting about 1 a.m., dark skies should help.
July 29: The gibbous moon is in Sagittarius, the stars of the ``teapot'' below and to its right.
July 31: The second full moon of the month is at 4:41 p.m., in Capricornus. By Dr. Thomas D. Nicholson Director, the American Museum of Natural History, New York