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The Night Sky of July

Dr. Wayne Wooten
Professor of Astronomy

For July 2016, the Moon will be new on July 4th. The waxing crescent moon will pass just south of Jupiter on the evening of July 9th. It will be first quarter, half lit and overhead at sunset on July 12th. The waxing gibbous moon will pass 8 degrees north of Mars on July 14th, and 3.4 degrees north of Saturn on July 16th. The Full Moon, the Hay or Thunder Moon, is on July 19th. The last quarter moon rises about midnight on July 8th. The moon is new on July 26th. On July 29th, the waning crescent moon will occult (cover) the bright star Aldebaran, the eye of Taurus the Bull, starting about 4:40 Am CDT for Pensacola residents. Watch this event with binoculars or a small telescope, and look for the star to reappear along the moons dark upper limb about 5:36 AM, in twilight.

Mercury and Venus are both still too close to the sun to see well this month. Look for both to join Jupiter low in the SW twilight in early August. The Earth passed Mars late in May, and so Mars is now getting smaller and fainter in our telescopes daily, but it still is bright orange-red in Libra in SE twilight skies. But it has now stopped retrograding, and draws closer to the claws of Scorpius by Julyís end. Jupiter is still well up in the west at sunset in the SE corner of Leo, but will be getting lost in the Sunís glare by August, so enjoy its moons, belts and zones, and Great Red Spot while you can. Saturn is also well placed for evening observing in July, just above Antares, the red heart of Scorpius in the SE. It is tilted 26 degrees toward us and the Sun, and the rings and moons are the most beautiful sight in the telescopic sky.

Overhead, the Big Dipper rides high at sunset, but falls lower in NW each evening. Good scouts know to take its leading pointers north to Polaris, the famed Pole Star. For us, it sits 30 degrees (our latitude) high in the north, while the rotating earth beneath makes all the other celestial bodies spin around it from east to west.

If you drop south from the bowl of the Big Dipper, Leo the Lion is in the SW. Note the Egyptian Sphinx is based on the shape of this Lion in the sky.

Taking the arc in the Dipperís handle, we "arc" SE to bright orange Arcturus, the brightest star of Spring. Cooler than our yellow Sun, and much poorer in heavy elements, some believe its strange motion reveals it to be an invading star from another smaller galaxy, now colliding with the Milky Way in Sagittarius in the summer sky. Moving almost perpendicular to the plane of our Milky Way, Arcturus was the first star in the sky where its proper motion across the historic sky was noted,by Edmund Halley.

Spike south to Spica, the hot blue star in Virgo, then curve to Corvus the Crow, a four-sided grouping. Saturn lies in Virgoís eastern feet this July. North of Corvus, in the arms of Virgo, is where our large scopes will show members of the Virgo Supercluster, a swarm of over a thousand galaxies about 50 million light years distant.

To the east, Hercules is well up, with the nice globular cluster M-13 marked on your sky map and visible in binocs. The brightest star of the northern hemisphere, Vega (from Carl Saganís novel and movie, "Contact"), rises in the NE as twilight deepens. Twice as hot as our Sun, it appears blue-white, like most bright stars. At the opposite end of the parallelogram of Lyra is M-57, the Ring Nebula.

Northeast of Lyra is Cygnus, the Swan, flying down the Milky Way. Its bright star Deneb, at the top of the "northern cross" is one of the luminaries of the Galaxy, about 50,000 times more luminous than our Sun and around 3,000 light years distant. Under dark skies, note the "Great Rift", a dark nebula in front of our solar system as we revolve around the core of the Milky Way in the Galactic Year of 250 million of our own years.

To the east, Altair is the third bright star of the summer triangle. It lies in Aquila the Eagle, and is much closer than Deneb; it lies within about 13 light years of our Sun. Use your binocs to pick up many clusters in this rich region of our own Cygnus spiral arm rising now in the east.

To the south, Antares is well up at sunset in Scorpius. It appears reddish (its Greek name means rival of Ares or Mars to the Latins) because it is half as hot as our yellow Sun; it is bright because it is a bloated red supergiant, big enough to swallow up our solar system all the way out to Saturnís orbit! Scorpius is the brightest constellation in the sky, with 13 stars brighter than the pole star Polaris! Note the fine naked eye clusters M-6 and M-7, just to the left of the Scorpionís tail.

Just a little east of the Scorpionís tail is the teapot shape of Sagittarius, which lies toward the center of the Milky Way. From a dark sky site, you can pick out the fine stellar nursery, M-8, the Lagoon Nebula, like a cloud of steam coming out of the teapotís spout. This beautiful new photo of it and M-20, the Trifid Nebula north of it, were taken with a new short focus wide field refractor scope.

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