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Observing Highlights for July: Milky Way Nights

July 2012 Cygnus portion of Milky Way Chumack

As Earth orbits around the sun, new constellations and stars rise and become dominant during different seasons. In the summer, constellations from Sagittarius and Scorpius to Cygnus and Lyra are prominent due to their positioning in the sky. These constellations, extending from the southern horizon and tracing a trail overhead, also trace the path of the Milky Way.

From a suburban or rural location, wait until the sky gets dark on summer evenings and your eyes have adjusted, then seek out the cloudy-looking swath that begins in the south and arches overhead to the north. The Milky Way flows through the Summer Triangle (marked by the stars Vega, Deneb, and Altair) and thickens in the south near the Teapot asterism in Sagittarius, which is also the direction of the center of our galaxy.

The Milky Way Galaxy and our solar system are not aligned in parallel planes but intersect each other at an angle. Therefore, planets and the moon occasionally cross through the Milky Way as seen from our position. On July 29, the moon will appear to pass in front of the Milky Way, in the direction of the galaxy’s center.

With a pair of binoculars or a telescope, you can slowly sweep the environs of the Milky Way and stumble upon nebulae, star clusters, and globular clusters. The area just above the Teapot is an especially rich field for deep-sky objects.

In the beginning of July, you can trace the plane of the solar system by spotting Mercury above the western-northwestern horizon just after sunset. To the upper left of Mercury will be a line of bright stars and planets. The first bright point of light will be the star Regulus in Leo, and beyond that will be the planet Mars, distinctively reddish. To the upper left of Mars will be two bright points of light relatively close together: the star Spica in Virgo and, above it and brighter, yellowish Saturn.

As the month wears on, Mars will edge closer and closer to the pair of Spica and Saturn. The moon will make this trio especially picturesque on July 24, when it lies between Mars and the Saturn/Spica duo. On July 25, the moon will have moved off to Spica’s left.

The full moon for July, sometimes called the Thunder Moon, occurs early in the month on July 3. This will set August up for two full moons, with the second full moon being considered a “Blue Moon”.

July has one notable meteor shower, the Delta Aquarids, which peaks on the weekend of July 28. Look toward the east late at night where the constellation Aquarius is rising. Up to 20 meteors an hour are possible. If the moon is bright and spoiling the view, just wait till August, when one of the best meteor showers of the year, the Perseids, occurs with only a crescent moon. 

Image: The Cygnus portion of the Milky Way. Credit: John Chumack

HS_KellyWhittKelly Kizer Whitt loves clean, clear, and dark skies. Kelly studied English and Astronomy at the University of Wisconsin-Madison and worked for Astronomy magazine. She writes the SkyGuide for AstronomyToday.com. You can follow her on Twitter at twitter.com/Astronomommy.

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