It’s wonderful how many things are visible in the night sky — things you can see with the unaided eye, without binoculars or a telescope. All you need to know is where to look and what to look for — the chance to help with that is what inspires me to write this column.
But it’s fun to look further sometimes. The problem is that telescopes are not easy to come by. (Look for me and my telescope this summer at the parks and piers of the Outer Cape.) But many people have binoculars lying around. It’s worth dusting them off and putting them to work viewing the stars.
Binoculars are described with two numbers, such as 8×32 or 10×50. The first number is the magnification, and the second number is the diameter of the front lenses in millimeters. So 8×32 binoculars — a very common size, and the type you likely have in a drawer somewhere — have 32-mm lenses and magnify the image eight times. That’s not a lot of magnification (telescopes can have 150x and higher magnification), but those 32-mm lenses gather much more light than your eyes can. Imagine an owl with its widely dilated pupils; it can hunt little critters in the dark because its eyes are gathering lots of light (and because its retinas have more low-light detectors).
More light means objects that are normally too dim to see become visible. Under optimal conditions, our unaided eyes can see, at most, about 2,500 stars. With binoculars, that number jumps to over 100,000.
All you need to do is step outside after dark and point the binoculars up. Anywhere you look you’ll see hundreds of stars, some looking like faint pinpricks, others like sparkling gems. The view is especially rich along the Milky Way, and summer is the best time of year to see it.
The Milky Way is the name of our galaxy — over 100 billion stars that are gravitationally bound and orbiting a massive black hole. It’s an immense spiral, with a dense core and relatively thin arms.
Our solar system lies in the suburbs of the Milky Way, about midway between the core and its wispy outer reaches. When you look at the Milky Way, you’re looking along the plane of our galaxy. From our distant perspective, the stars seem so close together that they blend into a cloudy haze that arcs across the sky like a heavenly road — thus the name, Milky Way.
Here’s how to find it. Face south and let your eyes adjust to the darkness. The faint glimmer of the Milky Way will eventually appear, stretching from the southern horizon up, overhead, and to the north. Once you recognize it, look at it through your binoculars. Slowly sweep along the curve of the Milky Way; tens of thousands of stars will pass before your eyes. You can get lost here and spend a lifetime just exploring our galaxy. It’s good to have a few landmarks along the way.
The first is Antares. It’s a bright red star, low in the southwest. It might be somewhat obscured by low-altitude clouds or haze, but it’s usually bright enough to punch through any murk. Its red color is apparent when you compare it to other nearby stars, especially through binoculars.
Now put the binoculars aside for a moment. Antares is part of the constellation Scorpius, the scorpion. Antares is the head (or heart, depending on whom you ask) of the scorpion. The claws are to the right (west) of Antares, and the long stinger is to the left. Much of the stinger will be hidden below the horizon, but its end rises in a curve.
From the stinger, look just a little further up. Now you’re looking at Sagittarius the Archer. The shape of this centaur and his bow are not so easy to make out; instead, look for the Teapot, an asterism formed by the brightest stars of Sagittarius. (An asterism is a shape or pattern of stars that isn’t an official constellation.)
Once you’ve found the Teapot, you’re looking directly at the dense core of the Milky Way. Notice how it’s wider and brighter here. That’s because the core is thicker and relatively packed with stars, in contrast to the disk. It’s like gazing at a city skyline from a hill in the suburbs, while behind you are the lesser lights of small towns.
Spend some time in the Milky Way with both binoculars and unaided eye. Next month, we’ll find even more beautiful things to see there. Until then, clear skies!