If you haven’t done so yet I’m nagging you to get binoculars. While any binoculars are better than none, the good ones for night sky viewing have larger objective lenses. For example, a set of 10 x 50 binoculars have 10 times magnification and 50mm objective lenses. Not only are they good for viewing the night sky, they are fine for all-around use, although a little big for the opera. 10 x 40 or 10 x 42 will give satisfying views too. Notice I’m keeping the magnification at 10x. This magnification is just about the maximum for hand-hold ability. Beyond 10x and any shakes get magnified too much, degrading the view. 10x is good for seeing some lunar craters, moons of Jupiter, globular star clusters, open star clusters, and many nebulae.
Now let’s talk the Summer Triangle. It’s an asterism, that is, a group of stars producing a recognizable pattern – but it’s not a constellation. Think the Big Dipper. It’s a recognizable pattern, but it’s not a constellation. The Big Dipper is part of the constellation Ursa Major (great bear). The summer triangle is a huge asterism, and getting high in the sky now, so, it’s very good for checking out.
After 9pm find an open space, maybe your driveway or side yard, and lay down a blanket, or if you’re concerned about critters, use something like a chaise lounge. Orient yourself so you are looking east while lying down. Get comfy on your back. This is a great position for using binoculars. Easier to hold steady and less fatigue.
While on your back looking up in the east you will see three bright stars that form a big triangle. The lower star, nearly directly east, is Altair (in Aquila, the Eagle). To Altair’s upper left is Vega (in Lyra, the Lyre). Then to Aquila’s direct left is Deneb (in Cygnus, the Swan, aka Northern Cross). Inside this triangle are a collection of open star clusters, typically younger stars that were born together in a molecular cloud and are gravitationally bound, but they will eventually drift apart.
Let’s start with a beautiful double star first. Its name is Albireo. Find it on the sky map I copied from Astronomy Magazine (I inverted the colors to make it easier to read). The stars are golden and blue. Then from Albireo scan toward Deneb. A little below the imaginary line is NGC 6885, a dim open cluster. A bit farther is NGC 6883, then two clusters that can fit together in your binocular field, M29 and NGC 6910. Also, bright star Sadr (γ Cygni) shows well with them. Using the chart, see how many clusters you can bag in the Summer Triangle.
A real treat is called the Coathanger. Scan from Altair toward Vega. It’s located about 1/3 of the way and it looks like a Coathanger! It is not a cluster; the stars are not associated with each other. It is a recognizable shape, called a what? NGC 6802 is nearby.
What’s in the Sky?
July 18-20; after sunset; west: A waxing crescent Moon interacts with Mars, Venus, and Mercury – use your binoculars.
