Night Sky Highlights for July-September, 2015
Solar System
Venus, Jupiter, and Mercury
This will be a great summer for viewing the planets. In July and early August, Venus and Jupiter will be close together in the western sky right after sunset. In fact, on July 1, these two bright planets will be only about 1/3 degree apart in a spectacular conjunction. In early August, they will be joined by Mercury, but it will be very low in the west and binoculars may be needed to see it. On the evenings of July 18 and 19, the crescent Moon will join Venus and Jupiter, and first magnitude Regulus will be nearby too. Their relative positions will be changing night by night, so check out the sky after sunset as often as you can.
Saturn
Saturn will be high in the evening sky throughout the summer. It is in Scorpius, just above the three stars that form the claws of the scorpion. With its rings now open wide from our vantage point, it will be a beautiful object to observe.
Perseid Meteors
Peaking on the night of August 12-13
One of the highlights of the summer is the annual Perseid meteor shower. This will be an ideal year for viewing the Perseids (as long as the weather cooperates), because the shower peaks around the time of the new Moon. The meteors can be seen as soon as it gets dark, but they are most frequent after midnight. Although they will peak on the night of August 12-13, this is a long-lasting shower, and quite a few Perseids can be seen for a week or more before and after.
Total Eclipse of the Moon
Night of September 27-28
This should be a very nice eclipse for North American viewers, weather permitting. Here are some of the key times, in Eastern Daylight Time:
9:01 pm: Partial eclipse begins (Moon enters umbra)
10:10 pm: Total eclipse begins
10:47 pm: Mid-eclipse
11:24 pm: Total eclipse ends
12:27 am: Partial eclipse ends (Moon leaves umbra)
Neptune
Neptune is in Aquarius, and it will be visible in the evening sky later in the summer and into the fall. At about magnitude 8, it can be spotted in binoculars or a finder scope if you have a map showing where to look for it, such as this one:
http://www.nakedeyeplanets.com/neptune.htm#finderchart
Its blue-green disk is 2.3 arcseconds in diameter and will show nicely with a medium-sized telescope at high power.
Deep Sky Objects
In the summer sky there are literally hundreds of deep-sky objects that are worth exploring with a telescope, and many of them are also visible through binoculars or simply with the naked eye. Here is just a small sample of some of the better-known targets.
Messier 13
Globular cluster in Hercules
Always a favorite for amateur astronomers, this group of about 500,000 stars is one of the most impressive globular clusters in the sky. It is high overhead throughout the summer.
Messier 5
Globular cluster in Serpens
After observing Messier 13, try finding Messier 5 for comparison. The overall magnitudes of these two clusters are about the same, but M5 is smaller and more condensed. It may appear brighter, but because it is so compact its stars are harder to resolve.
Messier 55
Globular cluster in Sagittarius
As a third point of comparison, try Messier 55, located to the west of the Sagittarius teapot. This globular is also similar in overall magnitude to M13 and M5, but it is more loosely structured, and so through a medium or large telescope its stars are quite easy to resolve as individual pinpoints of light.
Messier 23
Open cluster in Sagittarius
This is a large and bright group of over 100 stars that is a beautiful sight through a telescope at low power, and it can be readily seen through binoculars as well.
Messier 25
Open cluster in Sagittarius
Like Messier 23, this open cluster is large and bright, and it is another good target for a small telescope or binoculars.
Scutum Star Cloud
Milky Way star cloud in Scutum
This dense section of the Milky Way is a great sight for the naked eye, binoculars, or any telescope. On a dark night, it can be seen just south of the stars that form the tail of Aquila, the eagle.
Collander 399, the Coathanger Cluster
Open cluster in Vulpecula
Also known as Brocchi’s Cluster, this large group can be dimly seen with the naked eye on a clear dark night. Through binoculars or a small telescope, its coathanger shape is obvious to everyone who looks at it.
Beta Scorpii
Double star in Scorpius
The uppermost of the three stars that form the “claws” of the scorpion is a fine double star for observation with just about any telescope. The two component stars are magnitudes 2.9 and 5.1, and they are separated by about 14 arcseconds, so they are fairly easy to discern, even at fairly low magnification.
Epsilon Lyra
Double-double star in Lyra
Looking with the naked eye, young people with excellent eyesight can just barely tell that Epsilon Lyra is a double star. This becomes obvious through binoculars. But when observed through a telescope with a magnification of 100x or more, each of the two stars can be resolved into a close pair of stars with similar brightness.
Messier 57, the Ring Nebula
Planetary nebula in Lyra
While in Lyra, don’t forget to check out the famous Ring Nebula. Through a small telescope it can be seen as a small oval, and you might be able to see the slightly darker center. With larger telescopes, the ring shape is obvious.