Your first constellation: how to spot Orion

If you’ve never recognised a constellation in your life, start here. Orion is unmistakable: three bright stars in a perfect, tight row, with four more bright stars forming a rough rectangle around them. Once you’ve seen it, you’ll see it forever, and you’ll wonder how you ever missed it.

Orion is also useful. He’s one of the great signposts of the sky. From his three belt stars alone, you can find two of the brightest stars in the heavens and two more constellations, without an app or a chart.

When to look

Orion is a winter constellation in the northern hemisphere, but he’s visible from almost everywhere on Earth at some point in the year.

If you’re in the northern hemisphere, Orion dominates the evening sky from late November through March. He’s high in the south by 9pm in midwinter.

If you’re near the equator (Dubai, Singapore, Nairobi, Quito), Orion passes nearly overhead in winter. You get a better view than almost anyone.

If you’re in the southern hemisphere, Orion appears upside-down, and he’s a summer constellation there, visible from roughly December through April. His belt still points the way to Sirius, just from a new angle.

If you’re reading this between May and September in the northern hemisphere, Orion is hiding behind the sun. Come back in November.

Finding him

Look for three bright stars in a straight row, roughly evenly spaced and close together. That’s all you need. Nothing else in the night sky looks quite like Orion’s belt.

Around the three belt stars you’ll find four more:

Betelgeuse, upper left, a red supergiant. You can see its orange colour without any help.

Bellatrix, upper right, slightly fainter and pure white-blue.

Rigel, lower right, brilliant blue-white, often the brightest star in the constellation.

Saiph, lower left, fainter than the others but still clearly part of the rectangle.

Together these four form a lopsided rectangle, with the belt running diagonally through the middle. That’s Orion: the hunter, with raised club and shield, belt cinched, sword hanging.

The “sword” is three more objects just below the belt, and the middle one isn’t really a star. It’s the Orion Nebula, a stellar nursery about 1,350 light years away where new stars are being born right now. To the naked eye, it looks like a slightly fuzzy star. Through binoculars, you can see the cloud.

Using Orion as a signpost

This is where Orion earns his keep. The belt points to things.

Follow the belt down and to the left (southeast, from the northern hemisphere). The line takes you straight to Sirius, the brightest star in the night sky. Sirius is in Canis Major, Orion’s greater hunting dog. It’s so bright it twinkles violently when low in the sky, and people sometimes mistake it for an aircraft.

Follow the belt up and to the right (northwest). You arrive at Aldebaran, the orange-red eye of Taurus the Bull. A little further on, slightly off to the side, sits the Pleiades: a small, blurry-looking cluster of stars. Most people can count six or seven with their naked eye. Through binoculars, dozens.

Arc up and to the left from Betelgeuse and you pick up Castor and Pollux, the twin heads of Gemini.

That’s four major sky objects found from a single starting point. This is how every stargazer learns the sky. From one anchor, you learn the neighbours, and the neighbours teach you their neighbours.

What you’re actually looking at

The belt stars — Alnitak, Alnilam, and Mintaka — are massive, hot blue supergiants. They look close together from Earth, but they’re spread across hundreds of light years. They just happen to line up from our angle.

Betelgeuse, the red one in the corner, is a dying star. It’s puffed up so large that if you put it where our sun is, it would swallow Mercury, Venus, Earth, and Mars, and its surface would reach almost to Jupiter. It’s expected to go supernova at some point in the next hundred thousand years, maybe tomorrow. When it does, it’ll briefly be as bright as the full moon in our sky.

Rigel is also a supergiant, but a young blue one, about 860 light years away and roughly 100,000 times more luminous than our sun.

Everything you’re looking at in Orion has a story. The light reaching your eyes tonight left Betelgeuse when the Roman Empire was still standing. The light from Rigel set out around the Norman Conquest of England.

Tonight’s job

Step outside at a reasonable hour, after full dark but before midnight. Face south (or north, from the southern hemisphere). Look for three stars in a neat row.

When you find them, you’ve met the most famous figure in the sky.

Now trace the belt down and left, find the brightest star in the sky. Then up and right, find the orange one. You’ve just used a constellation to find two more stars you couldn’t name ten minutes ago. That’s astronomy.