Orion stands out in Northwest sky

  • Fri Jan 17th, 2014 10:08am
  • Life

By Mike Lynch

Out of the nearly 70 constellations we can see in the Northwest over the course of the year, it’s Orion who’s the big guy and probably the most recognized constellation in the sky.

At first glance Orion looks like an hourglass with the neck made up of a short straight line of three bright stars.

According to Greek and Roman mythology, the three stars make up the belt of the hunter and the hourglass is the outline of Orion’s torso.

This time of year Orion starts out in the southeastern sky after evening twilight and stalks his way westward through the rest of the night. By about 4 a.m. Orion slips below the western horizon.

According to mythology, he was a half-god, half-mortal who slept by day and hunted by night.

Orion is the home of many bright stars, star clusters and nebula.

Its hallmark is that perfect line of three stars in a diagonal row that make up the hunter’s belt.

From the lower left to the upper right the stars are Alnitak, Alnilam and Mintaka. These stars are nowhere near other. They just happen to be in the same line of sight.

Alnitak is 800 light-years from Earth. Alnilam is about 1,300 light-years away and Mintaka is nearly 690 light-years away.

Alnitak and Mintaka are actually both multiple star systems with Mintaka made up of at least five stars revolving around each other.

Orion’s brightest star, Rigel, resides on the hunter’s left knee and is a bright blue, giant star more than 770 light-years away. It’s believed to be very young, possibly only 10 million years old or so.

It’s much larger and more powerful than the sun and almost 100 times larger.

The second brightest star, Betelgeuse, pronounced by most as “beetle-juice,” shines in Orion’s armpit. Betelgeuse is an Arabic name, which means “armpit of the mighty one.”

Even with the naked eye, you can see that Betelgeuse is a giant red star, possibly more than a billion miles in diameter, the biggest single thing you can see from Earth with the naked eye.

Betelgeuse is also nearing the end of its life. Sometime in the next million years, Betelgeuse will explode in a tremendous supernova explosion.

While Betelgeuse may be dying, there’s also new life in Orion. Look below Orion’s belt for the three fainter stars that outline the hunter’s sword.

The middle star in the sword is fuzzy because it’s not a star but a nebulae, a 30 light-year-wide cloud of hydrogen gas and dust almost 1,500 light-years away.

It’s more than 20 times the diameter of our solar system and within it stars are being born.

All through our own galaxy and millions of other galaxies in our universe, stars form out of hydrogen nebulae. Because of gravity, globules of hydrogen begin to collapse, which creates compression.

If it’s massive enough, heat due to the compression will fire up nuclear fusion and presto, you have a star, shining brightly for billions of years.

The Orion nebulae is so big it could produce more than 10,000 new stars.

Using even a small telescope, you can see four new stars that have formed in the great nebulae of Orion. It’s called the Trapezium since the four stars are arranged in a tiny trapezoid shape.

These stars may be only 300,000 years old and are showing signs of developing new solar systems. In fact, it’s debated that one of the stars may be less than 50,000 years old.

Celestial hugging this week: In the early morning southern sky, just before morning twilight, look for the last quarter moon to pass by the bright planet Mars and the bright star Spica. The moon will be closest to Mars on Tuesday morning.

Mike Lynch, a broadcast meteorologist in Minneapolis, is the author of the book, “Stars, a Month by Month Tour of the Constellations.” Email him at mikewlynch@comcast.net, or check www.facebook.com/mike.lynch.12327.

The Everett Astronomical Society welcomes new members. See www.everettastro.org/.