The month of July was named for Julius Caesar in 44 BC. Before that it was named Quintilis, which is Latin for fifth. That was when March was the first month of the year.

July is the first full month of summer. Even though the days are still long and the nights are short, this is a great month to get outside to enjoy and learn more about the beauty of the night sky. You may have to deal with a few bugs, but there are generally far fewer sacrifices to be made in summer than in winter to enable us to really enjoy the myriad wonders lying beyond our relatively tiny solar system.

The highlights this July include Saturn near its best for the year, Jupiter still brighter than usual in our evening sky, Venus in our morning sky passing between two bright clusters in Taurus, similar to what Mars did two months ago, an asteroid in Ophiuchus named Hebe, the Delta Aquarid Meteor Shower, and even a bright comet named Johnson in Hydra and Libra.

In summer you are looking into the very center of the Milky Way galaxy when you look low in the southern sky just below Sagittarius and Scorpius. There is an invisible supermassive black hole lurking there at the very heart of our galaxy. We are not special in that regard, since nearly every galaxy, both the spirals and the ellipticals, has supermassive black holes spinning at their centers. Ours weighs in at about four million times the mass of our sun. Its event horizon stretches about 30 million miles, the distance from our sun to Mercury. An individual stellar black hole event horizon is only 10 miles across.

We even have a series of about 100 radio telescopes linked together across the entire globe, appropriately called the Event Horizon telescope, to study this black hole, called Sagittarius A, and an even much bigger one at the center of the monster elliptical galaxy named M87 in the constellation of Virgo. That one is located 50 million light years away and is only one of about 2,000 galaxies in that nearby cluster. The one at the center of M87 is about seven billion solar masses, or almost 2,000 times more massive than the one we can claim for our own. That one is shooting out an incredibly powerful beam of synchronized radiation at relativistic speeds about 5,000 light years long. Anything and everything in its path would be fried instantly.

All that may sound very dramatic, but our own black hole was 10 million times brighter and more powerful than it is now, only two million years ago, which is a mere two seconds in cosmic time. Those are called active galactic nuclei. Ours will probably become active again sometime in the not-too-distant future.

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We even think that we have recently found the fossil imprint of that powerful and ancient jet of radiation that used to shoot out of our black hole. It is the stream of lacy gas trailing behind the Large and Small Magellanic Clouds, our two closest satellite galaxies.

The Event Horizon telescope is studying these two supermassive black holes and will have much more good data by next year. It is designed to detect the light cast off when objects disappear behind that elusive boundary. It will essentially make the silhouette of this monster black hole become visible to us. It will open new frontiers in our understanding of gravity, and I am sure we have much to learn about this force, which is basically just the curvature or topography of the fourth-dimensional space-time continuum in which everything in this universe is embedded. The recent confirmation of the third official gravitational wave detected with LIGO also will add a little to our ever-expanding knowledge of this important and all pervasive, yet still mysterious force.

Saturn can be easily seen in Sagittarius now, just above the part of our sky marking the very center of our galaxy about 26,000 light years away. The ringed planet is still in westward or retrograde motion toward Antares, the bright orange giant star marking the heart of Scorpius. Saturn is just under a billion miles away.

Jupiter is about twice as close to us as Saturn, and is about six times brighter. Keep in mind that our little man-made mission, Juno, has taken many incredible pictures of the king of planets, with countless colorful swirls of clouds near its south pole. Jupiter will already set around midnight. Try to see some or all four of its largest Galilean moons with just a pair of binoculars.

Brilliant Venus rises in our eastern sky around 3 a.m. It is another six times brighter than Jupiter or 36 times brighter than Saturn. Keep watching it as it tracks eastward in direct motion between the famous Pleiades and the less famous Hyades star clusters in Taurus, following a very similar path that Mars took two months ago. Notice that it will be three degrees above the slender waning crescent moon on the morning of Thursday, July 20.

The Southern Delta Aquarid Meteor Shower will peak during the morning of Sunday, July 30. The moon will be first quarter, which means that it will set at midnight and be out of the way when the shower hits its peak of about 25 meteors per hour. You can expect almost that many meteors each night for the last five days of July from this shower. This is also a good warmup to the more famous Perseid Meteor Shower, which will be largely washed out by a bright waning gibbous moon on Aug. 12.

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Comet Johnson should get as bright as sixth or seventh magnitude this month and become easily visible in a good pair of binoculars if not even without any optical aid. Look for it in Virgo just to the left of Spica about the same distance that Jupiter is to the right of Spica. Then it follows an arc through Hydra the Sea Snake just to the west of Libra the Scales.

This is a comet with a hyperbolic orbit, which means it is not on a periodic orbit and it will leave our solar system. It was discovered on Nov. 3, 2015 by Jess Johnson at only 17th magnitude using the Catalina Sky Survey images. That is 21 magnitudes or 300 million times fainter than Venus.

JULY HIGHLIGHTS

July 1. The moon passes 3 degrees north of Jupiter in the morning.

July 3. Earth is at aphelion, or farthest away from the sun, at 94.5 million miles.

July 6. The moon passes 3 degrees north of Saturn in the evening.

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July 9. Full moon is at 12:07 a.m. This is also called the Hay or Thunder Moon.

July 10. Pluto is at opposition at 14.2 magnitude in Sagittarius the Archer at night. It takes 248 years to make one orbit around the sun and its status was changed to a dwarf planet 11 years ago.

July 14. Venus passes near Aldebaran in Taurus in the morning.

July 16. Last-quarter moon is at 3:26 p.m.

July 23. New moon is at 5:46 a.m.

July 25. The moon passes near Regulus in the morning. .

July 30. The southern Delta Aquarid peak tonight and first-quarter moon is at 11:23 a.m.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.


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