Tom Burns: Beginner’s guide to Orion


One of the great ironies of the holiday season is that a whole lot of telescopes end up under trees but few of them get used until May. It’s hard to point a ’scope when your feet are frozen to the ground.

One way to maximize your observing pleasure in winter is to carefully plan your stargazing session. One technique is the time-honored method of “constellation mopping.” Take a familiar star grouping and work your way through it.

The Orion is a good starter constellation for all you newbies out there in telescope land. Even the smallest of department-store telescopes will show a few objects in Orion.

Let’s find it first. Look south just after dark. You’ll see a line of three bright stars, which form the belt of the Hunter. The bright stars above the belt represent Orion’s shoulders. The reddish star on the left is the old supergiant called Betelgeuse.

To the right is Bellatrix. Orion’s feet are called Saiph, to the left, and Rigel, to the right.

The first object to look for in a telescope is the multiple star system called Sigma Orionis. Find Alnitak, the left-most belt star. Sigma, the naked-eye star just below it, should split into three stars at high magnification. The main star is called Sigma AB. AB is really two very bright and massive stars orbiting each other so closely that you cannot split them in a telescope. Nearby Sigma D has a distinctly reddish glow. Sigma E is a bit farther from D than D is from AB. You are looking at a system of five stars, two of which you cannot see, that are all orbiting each other in a complex cosmic dance.

Two of the stars in the belt are also multiple star systems. Look for single, dim companions next to Alnitak and Mintaka, the right-most star in the belt. Whether you can see them or not depends on the clarity of the sky and the size of your telescope.

Below Alnitak and Sigma is a great binocular object, the vertical line of stars called the Sword of Orion. In the middle of the Sword is the best telescope target in the heavens, the Great Nebula. Look for a complex fuzzy cloud, a glorious mass of glowing hydrogen in which stars are being born. At high magnification, the four stars in a rough square at the center of the nebula are called the Trapezium. These stars are newly born out of the hydrogen gas that surrounds them.

Single stars are much too far away to look like anything more than a point of light in a telescope. However, a quick look at Betelgeuse, Orion’s left shoulder, will help to bring out its reddish hue.

You are looking at a star much larger than the diameter of Earth’s orbit around the sun. Estimates vary, but if our sun were replaced by Betelgeuse, the star’s girth would extend far past Earth’s orbit, perhaps brushing the orbit of Saturn.

It has lived its short, 100-million-year life burning hydrogen at a prodigious rate. It has now turned red and swelled to enormous size in preparation for its death some time in the next million years or so.

Some familiar objects will be beyond the capability of your ’scope. Many folks have seen the images from the Hubble Space Telescope of the Horsehead Nebula, for example. A few know that it is located within Orion’s boundaries.

In my own quest to see the elusive Horsehead, I built larger and larger telescopes until I finally had one that barely fit in my car. I bought special filters and headed for the darkest sky I could find. Finally, several thousand dollars later, there it was: a faint wisp of light with a tiny dark notch in it.

The quest was noble, I suppose, but, frankly, stupid. During that period, my children had to do without luxuries like shoes. I am truly convinced that if astronomers ever discover the other end of the Horsehead, they’ll name it after me.

If you have difficulty finding these objects, perhaps the person who gave you the telescope forgot to give you a good set of star maps. I know, I know. You have a star map on your smartphone. It’s great for discovering if “that bright thing over there” is a planet or not. However, when it comes to zeroing in on specific objects and finding them in your telescope, nothing beats a larger-format, printed set of maps.

As far as star maps go, I’d recommend Guy Consolmagno’s “Turn Left at Orion” for all you beginners out there. With it and a telescope of practically any size, you’ll find plenty to see. Don’t forget to purchase one of those little red LED flashlights to look at the star maps contained therein. You don’t want to spoil your night vision.

Some of you are saying: “But my telescope has computer control. I’ll just use that to find things.” When you use the computerized guiding system, the object you’re viewing belongs to the telescope. When you find it yourself, it belongs to you.

Do yourself a favor. Learn the sky, and then pass on that ancient knowledge to the next generation. We humans are fleeting things when it comes to the universe. Our knowledge lives a lot longer if we pass it on.

The first step is to bundle up and go outside. The universe awaits!

Tom Burns


Tom Burns is director of the Perkins Observatory in Delaware.

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