Summer stargazing has many enemies, or should I say challenges, including city lights, moonlight and mosquitoes.
You can fight city lights by driving out to the countryside and you can put on life-saving antibug juice to fight off the skeeters, but when it comes to moonlight, timing is everything. The less moon the better, and over the next week or so there will be very little moonlight. Galaxy gazing will be wonderful.
It’ll be a great show, but it’ll also be a late show, so you might want to turn this event into an overnight campout.
So there you are, gazing into the summer heavens. How many stars can you see with your naked eye?
Conventional astronomy textbooks say you can see about 3,000 stars with the naked eye but I’m sure there are a lot more than that.
You can’t help but notice the bright band of milky light that bisects the sky from north to south like a bold artist’s stroke. You may have been taught at an early age that the band is the Milky Way galaxy.
While that’s certainly true, you have to realize that all the start you see, including the sun, are members of our home galaxy, the Milky Way. That artist’s band across the sky is just the thickest part.
If you could jump into a magical spaceship and fling yourself out and away from the Milky Way, what you would see in your rearview mirror is a group of about 1 trillion stars in the shape of a giant CD, broken up into spiral arms with a large hump in the middle.
The Milky Way is a little more than 100,000 light-years in diameter and 10,000 light-years thick, with one light year equal to about 6 trillion miles. Our sun is about 60,000 light-years from the center of the galaxy in one of the arms.
When you see that milky band of light across the sky, you are looking edgewise into our galaxy. All the stars that we see orbit around the center of the Milky Way. Our sun takes more than 200 million years to make one circuit. In case you’re wondering, the center of the Milky Way lies in the direction of the constellation Sagittarius the Archer, more commonly known by its nickname, “the teapot”, because that’s what it really looks like.
The Milky Way band is not really much brighter around the teapot, because there is a lot of dark interstellar gas and dust that blocks the “hump” at our galaxy’s center. It’s been said that if we could see the Milky Way’s central region unobstructed, that area of the sky would be much brighter than a full moon.
Lie back on the ground and just roll your eyes all across the sky and especially around the Milky Way band. With just a pair of binoculars you’ll see all kinds of celestial treasures, such as bright nebulae clouds, star clusters and dark rifts. You might even see a few human-made satellites rolling across the heavens.
It’s a great time to get to know the summer constellations.
One more thing to keep in mind while you’re galaxy gazing: Our Milky Way galaxy is only one of millions of other galaxies out there. The Hubble telescope has seen galaxies more than 15 billion light-years away.
Kick back and enjoy the greatest show off Earth.
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and author of the new book “Washington Starwatch,” available at bookstores and on his Web site, www.lynchand thestars.com.
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