How to Find Orion and the Orion Nebula

If you learn only one constellation, make it Orion. It is bright, it has a shape almost everyone can pick out, and it holds a genuine deep-sky treasure you can see without a telescope. NOIRLab, the US national center for ground-based optical astronomy, notes that because Orion lies near the celestial equator, "it is visible from most of the world."

Here is how to find it, what its main stars are called, and how to use it as a signpost to other sights.

1. When Orion is up

NOIRLab calls Orion "a prominent constellation during winter in the northern hemisphere." In autumn it rises later in the night, and by the depths of winter it is well placed in the evening sky. NASA's Hubble team says the Orion Nebula, inside Orion, "is best observed during January."

2. Step 1: Find the belt

Start with three stars in a short, straight row. Royal Museums Greenwich describes Orion's Belt as "one of the most recognisable asterisms," made of three bright stars that form a straight line, and notes it "can be seen even in light-polluted areas."

NOIRLab names them:

• Alnitak, which is a triple star system,
• Alnilam, the middle and brightest of the three, and
• Mintaka, the faintest of the three.

3. Step 2: Find the four corners

Around the belt, four bright stars form a large, roughly rectangular shape. NOIRLab lists them as Betelgeuse, Rigel, Bellatrix, and Saiph. Together with the belt, Orion's seven brightest stars make what NOIRLab calls "a distinctive hourglass-shaped asterism."

Two of the corners are worth knowing by sight:

• Betelgeuse marks one shoulder. NOIRLab describes it as a massive red supergiant and a variable star, and Royal Museums Greenwich calls its color "deep orange-red."
• Rigel marks a foot on the opposite corner. Royal Museums Greenwich describes it as a blue supergiant, and both sources list it among the brightest stars in the night sky.

The color contrast between orange Betelgeuse and blue-white Rigel is one of the easiest star colors to notice with the unaided eye.

A fainter star, Meissa, marks Orion's head above the shoulders.

4. Step 3: Drop down to the sword and the Orion Nebula

Below the belt hangs a shorter, fainter line of three "stars" called Orion's sword. NOIRLab points out that the middle one "is in fact not a star but the Orion Nebula."

NASA's Hubble Messier catalog gives the details on this object, also known as Messier 42 or M42:

• It sits in a "prominent location just below Orion's belt."
• It "can be spotted with the naked eye" from a dark sky site.
• Its apparent magnitude is about 4.
• It is a stellar nursery, "the closest large star-forming region to Earth."

On distance, NASA's Hubble page gives about 1,500 light-years, while NOIRLab's constellation page says about 1,200 light-years. Distance estimates for nebulae vary between sources; either way, the light you see left the nebula well over a thousand years ago.

From a dark site the middle sword "star" may look a little softer than its neighbors. For a better look, NOIRLab says the nebula is "pleasing to observe through binoculars and telescopes." With a telescope, look for the Trapezium, four massive young stars at the nebula's heart that NASA says are arranged in a trapezoid shape.

5. Use the belt as a pointer

Orion works as a signpost to two famous neighbors.

Sirius. Royal Museums Greenwich notes that diagonally off to one side of Orion sits Sirius, in Canis Major, "the brightest star in the night sky," about eight and a half light-years away. Once you have Orion, the brightest star nearby is hard to miss.

The Pleiades. Royal Museums Greenwich also describes the other direction: follow "the straight line of Orion's belt" to the bright reddish star Aldebaran, and then on to the Pleiades, a small cluster of blue stars. About six or seven are visible to the unaided eye, though the cluster has over 1,000 members.

6. What "in Orion" really means

Star maps draw Orion as a hunter with a raised club, but the International Astronomical Union does not define official stick figures. Instead, the IAU defines each constellation as an area of sky inside agreed boundaries. Those boundaries, drawn by Eugène Delporte, were approved at the IAU General Assembly in 1928 and published in 1930. So when astronomers say the Orion Nebula is "in Orion," they mean it lies inside that patch of sky, not that it is part of the stick figure.

7. A quick Orion tour

1. Find three bright stars in a short straight line: the belt.
2. Look for the four bright corners, with orange Betelgeuse and blue-white Rigel on opposite sides.
3. Drop below the belt to the sword and find the fuzzy middle "star," the Orion Nebula.
4. Find bright Sirius diagonally off to one side, then follow the belt's line the other way to Aldebaran and the Pleiades.

8. Key takeaways

• Orion is a winter constellation for the Northern Hemisphere and, lying near the celestial equator, can be seen from most of the world.
• Its belt stars are Alnitak, Alnilam, and Mintaka; Betelgeuse, Rigel, Bellatrix, and Saiph form the corners.
• The middle "star" of the sword is the Orion Nebula, a star-forming region visible without equipment from dark skies.
• NASA lists the Orion Nebula at about 1,500 light-years and says it is best observed in January.
• Bright Sirius sits diagonally off to one side of Orion, and the belt's line leads to Aldebaran and the Pleiades.