Last month, I started a tour of the evening sky by describing the astronomical objects I would point out as it was getting dark. I hope you got to go outside while it was still warm to see some of them. This month, I will continue this virtual star party by suggesting a few things to look at through binoculars after it gets darker.
A standard pair of 10 x 50 binoculars gathers about 50 times the amount of light as your naked eye, so looking through binoculars, you can see things that are 50 times dimmer. Most people are surprised by how many more stars show up by simply scanning along the Milky Way with binoculars. This month is great for viewing a variety of different types of objects – planets, clusters, nebulae and at least one galaxy.
Jupiter will be setting by 8:15 p.m., so you might want to start with the visible planets. Because the moon is so bright, I usually like to leave that until last. But since it is setting about 10 p.m., don’t wait too long. Jupiter and Mars are the bright planets to the southwest and south along the ecliptic. Saturn and the red star Antares are between Jupiter and Mars. Saturn is in the middle of the Milky Way. Depending on the resolution of your binoculars, you might be able to see Saturn as a football-shaped spot rather than a tiny disk. Somehow, I never find Mars very impressive through binoculars, but take a look anyway because it is so easy to see.
By scanning the Milky Way up from the southern horizon, you should be able to see dozens of open clusters. Open clusters simply look like a dense group of stars. They are the result of recent star formation so are often some of the youngest stars you can see. One of the brighter clusters is M8, or Messier 8, also called the Lagoon Nebula. You can see this with your naked eye as a dim fuzzy spot about 3 degrees (three pinky-finger widths) below and to the right of Saturn. This cluster also has a halo of glowing hydrogen gas lit up by the ultraviolet light emitted from the biggest stars in the cluster. Photographs show the cloud as red, but like most things in the sky, it is too dim for your eyes to pick up any colors.
Five degrees to the left of Saturn is M22, a good example of a globular cluster. Globular clusters are groups of some of the oldest stars. More like miniature galaxies, they are outside the disk of the Milky Way but orbit it in random directions. Binoculars will show globular clusters as little fuzz balls without any of the individual stars that can be seen in larger telescopes.
The Andromeda galaxy, M31, is the best galaxy visible with binoculars and is also the most distant object visible with your naked eye. A star chart will help you locate it between the “W” of Cassiopeia and the inverted “V” of Andromeda in the northwestern sky. Typically, only the central bulge is visible. The spiral arms that show up in photographs are only visible on the darkest nights or with extra large binoculars. They extend as far as six side-by-side full moons. Telescopic views are often too narrow to see the entire galaxy, so binoculars may be your best viewing option.
This monthVenus is making the transition from evening star to morning star, so this is a month when it will be hard to see because it is so close to the sun.
On Saturday night, the four Galilean moons of Jupiter will be arranged from left to right in order of their distance from Jupiter. Their positions will change from night to night, often by quite a bit.
Uranus is barely visible with your naked eye, and this month, it is at opposition, making its closest approach to Earth on Oct. 23. It is close to the tails of the fish in Pisces. On Oct. 24, the full moon will be less than 10 degrees below and to the right of Uranus. Since opposition is so close to the full moon, the sky might be too bright to get a good view. I suggest using a star chart or smartphone app on a very dark, clear night to see which of the dim dots is Uranus.
Charles Hakes teaches in the Physics and Engineering Department at Fort Lewis College and is the director of the Fort Lewis Observatory. Reach him at firstname.lastname@example.org.