July is an excellent month for stargazing. The rich star fields of Scorpius and Sagittarius finally come into view over the southern horizon for northern stargazers, and nearly overhead for southern-hemisphere observers. This year Saturn remains beautiful in a telescope in the constellation Libra. Venus Mercury and the Moon rise together later in the month in the pre-dawn hours. And you also get a chance to see the asteroids Ceres and Vesta make their closest apparent approach since, well, perhaps ever. Here’s what to see in the night sky this month…
* * * Tour the Night Sky With a Small Telescope * * *
“What To See In A Small Telescope” takes you to nearly 100 deep-sky sights in the night sky from July through September. Includes maps and instructions to find every object, and tips on what to look for. Now available from One-Minute Astronomer. Click here to learn more…
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3 July. Earth reaches aphelion, the farthest point in its elliptical orbit from the Sun. This year it will lie at a distance of 152,093,481 km. At aphelion Earth moves slowest in its orbit, which means summer in the northern hemisphere lasts very slightly longer than winter (and vice versa for the southern hemisphere).
5 July. First Quarter Moon, 11:59 UT
4-5 July. The large asteroids Ceres and Vesta come within 10 arcminutes of each other, one of the closet apparent approaches in history. Though smaller, Vesta is brighter than Ceres right now at magnitude 7.1. Ceres is magntiude 8.4. The pair will lie about 1.5º southwest of zeta Virginis (also called Heze). They are an easy target in binoculars. Ceres, the largest of the asteroids, has a diameter of 952 km, while Vesta spans about 525 km, just a little smaller than 2nd-largest Pallas. Ceres will appear fainter because its about 74 million km farther than Vesta, and also because it has a darker surface. See the map below, courtesy of Sky and Telescope, for exact locations.
7 July. Look for Saturn, still big and beautiful in a telescope this month, near the waxing gibbous Moon in the constellation Libra. The planet is getting a little smaller as Earth moves away from it, but the rings are still more than 20º from edge on and very fine in a telescope well after sunset, after the planet rises higher in the sky.
12 July. Full Moon, 11:25 UT
13 July. Mars passes about 1.3º north of the bright white star Spica in the constellation Virgo. Look for the pair in the west or southwest well after sunset. The Red Planet makes a splendid color contrast with Spica. The planet is shrinking fast and is well past optimum viewing in a telescope. But it’s still bright enough to attract attention on a warm July evening.
19 July. Last Quarter Moon, 02:08 UT.
24 July. Look for the waning crescent Moon, Mercury, and Venus in the predawn sky (see below). The three objects are lodged between the bright stars Castor and Pollux in Gemini and the shoulders of rising Orion.
26 July. New Moon, 22:42 UT
July 28-30. The Southern Delta Aquariids peak. This meteor shower runs from mid-July to early August, but usually peaks at the end of July. The shower shows 5-10 meteors per hour, with more visible well after midnight. These meteors tend to leave a long, lingering trail which sets them apart from most other meteors. Wake up early to get the best view about 2 hours before sunrise. Meteors will be visible from the northern and southern hemispheres.