Night Sky Highlights for July-September 2018
Perseid Meteor Shower
Week of August 10-15 (and beyond)
This promises to be an excellent year for observing the Perseids, because they will peak around the time of the new Moon so the sky will be nice and dark. Weather permitting, the best viewing should be on the night of August 12 (and ASNH will sponsor a public viewing night at the Ansonia Nature Center (map). But occasional Perseids can be seen in night sky for several weeks starting in late July, so keep an eye out for them.
There will be a good opportunity to observe Mercury during the first half of July, when it will be low in the west right after sunset. You will need a clear view of the western horizon.
Venus will be easy to see in the west after sunset throughout the summer this year. At about magnitude -4, it is the brightest object in the sky besides the Sun and the Moon.
This summer, Mars will make its closest approach to Earth since 2003. It is closest (and of course largest through a telescope) on July 31, when it will be 24.3″ in diameter (more than half the apparent size of Jupiter). But don’t just wait for that one night, because it will be quite large throughout July and August.
The giant planet will be easily visible in the evenings throughout the summer, in the constellation Libra. This will be a perfect time to observe its cloud bands, the red spot, and its four brightest moons.
Saturn is in Sagittarius, and it will rise around sunset in the beginning of July. It will be well placed for evening observing this summer. Its rings continue to be tilted at a good angle for viewing them from our vantage point.
Uranus and Neptune
Uranus is in Pisces, and Neptune is in Aquarius. They will be better placed for convenient evening observing this fall, but if you want to stay up late and view them during the warm summer months, you will need a finder chart such as the one in this article from the Sky & Telescope website:
Deep Sky Objects
At just about any summer observing event, you are likely to see the old favorites (the Ring Nebula, the Wild Duck Cluster, Messier 13, etc). But there are many more great objects in the summer skies that are not observed quite so often. A few of these are listed below. For each object, click on the star-hop chart to get instructions and printable maps showing how to find the object in the evening sky.
Messier 10 and 12
Globular clusters in Ophiuchus
These two clusters in the middle of Ophiuchus are both large and fairly bright, and they are good targets for telescopes of all sizes. Medium to large scopes will show hundreds of individual stars in both clusters. The stars of M12 are less densely packed, making them easier to resolve all the way to the center of the cluster. Star-hop chart
Messier 16, the Eagle Nebula
Nebula and star cluster in Serpens
The Eagle Nebula is a not especially bright when observed visually. The cluster of stars is easy to see, but even through a large telescope the nebula is dim and diffuse.Look for a faint glow within and around the star cluster, and use a nebula filter if you have one. Star-hop chart
Messier 20, the Trifid Nebula
Diffuse nebula in Sagittarius
Through a telescope, the Trifid Nebula consists of two hazy balls of light. With a medium or large telescope, you can see dust lanes in the larger and brighter section that divide it into three lobes and give the object its name. Star-hop chart
Open cluster in Sagittarius
Just over 1/2 degree northeast of Messier 20 (the Trifid Nebula) is M21, an open cluster of several dozen stars that is ideal for telescopes of all sizes. Star-hop chart
Messier 23 and 25
Open clusters in Sagittarius
With the naked eye, you can see Messier 24, a very rich section of the Milky Way about 1.5 degrees across. It is a wonderful sight in binoculars or a telescope with a wide field of view. It is flanked by two bright open clusters, M23 to the west and M25 to the east. Both of these are nice sights in binoculars and telescopes at low power. These two open clusters are each about 2000 light years away. Star-hop chart
Globular cluster in Sagitta
In this middle of the small but distinctive constellation of Sagitta, the arrow, there is a fine globular cluster that is easy to locate. M71 is loosely packed with stars, and a telescope with medium or high magnification will resolve the stars nicely. It is particularly attractive with its Milky Way background full of tiny stars. Star-hop chart
Globular cluster in Hercules
Although its neighbor in Hercules, M13, gets all the attention, Messier 92 is also a very impressive globular cluster and it is definitely worth tracking it down. The cluster is about 27,000 light years away and contains several hundred thousand stars. Star-hop chart
Red carbon star in Aquila
At the tail end of Aquila is v Aquilae, one of reddest stars visible in the sky, due to the presence of carbon in its atmosphere. Its magnitude varies from 6.6 to 8.4, so it should be easily visible in any telescope. Just 1/2 degree to the southeast is the small planetary nebula NGC 6751 (see below). Star-hop chart
Planetary nebula in Aquila
If you are using a telescope with an aperture of at least 6 inches, after observing v Aquilae (see above), look just 1/2 degree to the southeast and you should be able to spot NGC 6751, a small planetary nebula. High magnification will help to identify it as a nebula and not just a star. Star-hop chart