The Orion Nebula
 
Picture of the Orion Nebula courtesy of J-2 Space.Photo Credit: C.R. O'Dell (Rice University), and NASA.

The Orion Nebula, in the constellation Orion, is one of the most beautiful objects in the night sky. Hanging from Orion's belt is a sword that is made up of three fainter stars. The middle "star" is actually not a star at all, but the Great Orion Nebula. To the naked eye, it looks like a star, however, with binoculars or a telescope, you can see that it is actually a huge cloud of glowing gas about 1,600 light years away.

One part of the nebula is the Orion Molecular Cloud, which is the birthplace of many new stars. This cloud of gas has a mass about 2,000 times the mass of the sun. Gravity causes the gas from this cloud to collapse slowly to create stars.

 

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Photo of the constellation Orion courtesy of Kitana's Home page of Astronomy

At the end of its life, when all of the stars have been created, what will remain is a cluster of several hundred to 1,000 stars.These stars are outshined by a few very massive, very bright stars called the Trapezium.The Trapezium is made up of just a few stars, but is brighter than all the rest of them combined.It is the Trapezium that lights up the entire Orion Nebula.Perhaps, in 100 million years or so, there will be planets like the Earth forming around some of the new stars in the cluster.Indeed the dense cloud may hide stars with planets from our view today!

On winter evenings in the northern hemisphere, the three bright stars (Alnitak, Alnilam, and Mintaka) that form Orion's Belt are easily visible to the naked eye low in the southern sky. The bright star that forms Orion's left shoulder is Betelgeuse (pronounced beetle-juice!). This means "The Armpit of the Central One" in Arabic. Can you find Orion in the night sky? Try to find the Orion Nebula with binoculars or a telescope.

Constellation Chart (Equatorial Region ) Courtest of Sky Publishing Catalog: ESSCO Classroom Publications

Ledgends of the Sky

Besides the Big Dipper, the constellation Orion is one of the most recognizable patterns of stars in the northern sky. Orion is the hunter. He stands by the river Eridanus and is accompanied by his faithful dogs, Canis Major and Canis Minor. Together they hunt "stellar animals" -- including Lepus, the rabbit, and Taurus, the bull.

According to Greek mythology, Orion was in love with Merope, one of the Seven Sisters forming the Pleiades, but she rejected him. Orion's life ended when he stepped on Scorpius, the scorpion. The gods felt sorry for him, so they put him and his dogs in the sky, along with animals to hunt. As an act of kindness, the gods placed Scorpius on the opposite side of the sky, so Orion would never be stung again.
 
Photo of galexy NGC 2997 courtesy of The Anglo-Australian Observatory

But if you think THAT'S big, think about a galaxy! Above is a picture of a galaxy called NGC 2997. We live in the Milky Way where our sun is one of 200 to 400 billion stars. Like NGC 2997, our Milky Way is a spiral galaxy. If you could fly across our galaxy at light speed, it would take 100,000 years to make the trip!

How Small? Small to Tall Small Links Orion Nebula Dragonfly
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