How would you like to see about a million stars, all crammed together in a tight ball in our Butler night sky? Well you can do just that.

The Great Hercules star cluster is one of the true treasures of the summer sky, but like a lot of worthy celestial treasures you have to dig for it. Think of it as an extra credit project for a beginning stargazer.

The Hercules Cluster, known astronomically as M-13, is a prime example of a globular star cluster. Now, there are hundreds and hundreds of star clusters all around the night sky, anytime of the year. Just slowly scan the heavens with any old pair of binoculars and you can’t help but find them.

Most of these are open star clusters made up of groups of young stars that recently formed out of the same hydrogen gas cloud. These baby stars are generally anywhere from 50 to 150 million years old, which is hardly any time at all when you’re talking astronomy.

Globular clusters like M-13 are different. They are spherical swarms of thousands or even hundreds of thousands of stars packed in a small area, usually less than 300 light-years in diameter. Globular clusters are made up of old stars generally more than 12 billion years old, and more than 140 globular clusters form a giant halo around our Milky Way Galaxy.

In a way, they are part of the outer structure of our home galaxy, or what some astronomers call satellites of our Milky Way. Because of this, globular clusters are a heck of a long ways away. The Hercules Cluster, M-13, is about 25,000 light-years away. Remember, just one light-year equals 6 trillion miles. The bottom line is that you won’t get to M-13 on your summer vacation!

This time of year you can launch your quest for the great Hercules globular cluster as soon as it gets dark enough, around 10:30 p.m. For all practical purposes it’s not visible to the naked eye, but with a dark enough sky, such as in the outer suburbs or the countryside, you should be able to hunt it down with a decent pair of binoculars or a small telescope.

When you get it in your scope, I can just about guarantee you’ll fall in love with one of the true jewels of the heavens, especially if you’re observing it in the dark countryside.

At the end of evening twilight, M-13 is located nearly overhead on the west side of the faint constellation Hercules.

I think the easiest way to find it is to use the two brightest stars in the early evening summer sky, Vega and Arcturus. They also happen to be nearly overhead. Vega is just to the east of the zenith in the faint constellation Lyra the harp, and Arcturus is just to the west in the constellation Bootes the farmer.

Draw a line between Vega and Arcturus across the top of the sky. M-13 will be just short of the halfway point from Vega to Arcturus. Scan that area with your binoculars or telescope and see if you can spot what looks like a little fuzz ball.

That little fuzz ball is M-13, the Hercules Cluster. It’s a gigantic city of around a million stars, jammed into a sphere less than 150 light-years across. That’s what I call celestial congestion.

With enough magnification and light gathering, you may see some individual stars at the cluster’s edge. The light you see from M-13 this summer left that globular cluster in the year 23,000 BC.

M-13 is by far the best globular star cluster in the summer sky, but there are several other great ones. Go ahead and Google “summer globular clusters” and you’ll see what I mean.

I do want to point out two other globular clusters that shouldn’t be too hard to find. The first one is also in the constellation Hercules the Hero. It’s M-92, which you can see on the diagram is really close to M-13.

Facing south, take a good pair of binoculars or a telescope and scan the area about eight degrees, or just less than the width of your fist held at arm’s length, to the upper left of M-13 and you should be able to spot M-92. It’s just about as bright as M-13 and a little farther away at a distance of 27,000 light-years.

Another one of my favorite globular clusters is M-4 and that’s super easy to find. It’s just to the right of the bright star Antares in the bright constellation Scorpius the Scorpion.

With binoculars or a small scope you shouldn’t have too hard of a time spotting it. It’s physically a smaller globular cluster than M-13 or M-92, but it shows up so well because it’s only a little more than 7,000 light-years away.

Have gobs of fun hunting globular clusters!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Pennsylvania Starwatch”, available at bookstores and at www.lynchandthestars.com.