This time of year you have the best chance to see the farthest thing away that you can see with the unaided human eye in the northwestern Washington night sky.
Away from city lights, look in the southeastern sky in the early evening and you may see the Andromeda Galaxy, next-door neighbor to our Milky Way Galaxy.
Remember the movie “The Andromeda Strain”? Well that’s what your eyes will have to do to spot the grand island of stars.
A couple of weeks ago, I featured the constellations Pegasus the Winged Horse and Andromeda the Princess that are literally linked together. The main part of Pegasus is called the “Square of Pegasus.”
Look for the square orientated diagonally in the southeastern sky. It’s easy to see because the stars that make it up are some of the brightest in that area.
Next look for two curved lines of stars that arc off to the left of the star Alpheratz (pronounced Al-fee-rats), on the left corner of the Square of Pegasus. The lower arc of stars is much brighter than the upper arc. The lower arc outlines the wings of Pegasus the Winged Horse. The fainter upper arc outlines Princess Andromeda.
The best way to find Andromeda is to follow the lower line or wing of the horse two stars to the left of Alpheratz. You’ll come to the star Mirach that’s fairly bright. Look for the next two brightest stars you can see above Mirach, and just to the upper right of those two stars look for a small misty patch of light that kind of looks like a tiny cloud.
That’s the Andromeda Galaxy.
If you can’t see it with the naked eye or you’re forced to look for it from areas of city lighting, all is not lost. Take a small telescope or even a halfway decent pair of binoculars and scan that part of sky.
All you’ll see is a ghostly patch of light. Even with large telescopes you’re not going to see it that much better.
That little ghostly patch of light is made up of the collective light of possibly more than a trillion stars at a distance of 2.5 million light-years away.
Just one light-year equals nearly 6 trillion miles. Since a light year is defined as the distance light travels in a year’s time, the light that you’re seeing from Andromeda has been traveling to your eyes for 2.5 million years.
Despite that incredible distance, the Andromeda Galaxy and the Milky Way are the closest neighbors to each other, but without a doubt Andromeda is a larger galaxy, possibly twice the diameter of the Milky Way.
Like our home galaxy, most of the mass that makes up Andromeda is invisible, what astronomers call dark matter, which still remains a big mystery.
Less than a hundred years ago the Milky Way Galaxy was all we thought there was to the universe. What we now know as the Andromeda Galaxy was then thought to be just a big cloud of nebulosity.
That all changed in the 1920s when Edwin Hubble and his assistant, Henrietta Leavitt, discovered that the Andromeda Galaxy was a heck of a lot farther away than it was previously believed to be.
They used what is known as cepheid variable stars to gauge just how far away Andromeda is. Cepheid stars vary in size and brightness over a period related to average brightness. They’re what astronomers call “standard candles.”
By observing the cepheid variable stars brightening and dimming cycle Hubble and Leavitt determined that the Andromeda nebulae was farther away than anyone ever thought. It was concluded that it was a whole other galaxy of stars independent of our Milky Way.
The Andromeda Galaxy and the Milky Way Galaxy are on a collision course, approaching each other at an estimated 50 miles a second. At that rate they will collide and merge in about 4 billion years. Maybe you shouldn’t wait up for it.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Washington Starwatch,” available at bookstores and at his Web site www.lynchandthestars.com.
The Everett Astronomical Society welcomes new members. Go to www.everettastro.org.
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