« Something Cool, Way Cool | Main | Photons: They Ain't Just for Torpedoes »
New Mysteries of the Milky Way
The Galaxy >
Your assignment this week, should you decide to accept it, is to go out and take a look at the Milky Way. This is no impossible mission, especially during the summertime. And it will be a rewarding one.
But before you go out, read below. There's some news coming out about The Way that will make you more appreciate the splendor of the whole experience.
The Milky Way, as you know, is the common name we give to our home galaxy, a spiral beauty consisting of more than 100 billion stars and great collections of gas and dust.
During the summer our orbit takes us to the side of the sun where Earth's "night" side opens toward the center of the galaxy where stars reside in great and incomprehensible number. It is then that the Great White Way is easily discernible in the night sky.
By looking towards the south --- in Sagittarius, to be exact --- you may even have noticed that the Milky Way is at its bulkiest. There, about 28,000 light years away, lies the hyperactive center of our galaxy. And within that lies, probably, a supermassive black hole.
Wouldn't it be nice if our solar system were further out on the disk so we could catch a richer, fuller view of the whole shebang? Or, conversely, what if we were closer to the center and had a sky filled with tens of thousands of bright gemlike stars in a monstrous band of light bleeding across the sky?
Astronomers tell us we should be thankful for the view we have now --- that we have the best, and safest, seat in the whole House. How's that?
Well, of course we'd never want to be at the core of the galaxy. The supermassive black hole residing there can ruin an otherwise perfect day.
And just a little further out from center puts us in a place that is crammed with stars. These stars can tug our tiny planet out of its perfect orbit in a heartbeat. Moreover, supernovae and other great stars flood the place with intense, deadly radiation.
But even far from the center is no place to be, either, apparently. A group of astronomers from the University of Washington, headed by Guillermo Gonzalez, says looking for a life-support planet all the way out to about 15,000 light years would be a fruitless quest!
Gonzalez says that here there is so much dust and debris
from previously exploded stars --- planet building material, in other
words --- that rocky planets forming around single stars would be enormous.
This means flattened surfaces covered with water, probably surrounded
by a lethal atmosphere. No vacation spot, that.
Further out from the center than about 40,000 light years is no place
to settle down, either. There just isn't enough stuff out there to make
planets like ours, perfect rocky bodies fit for life.
It's turning out that if one wants to find a life-support planet in our galaxy, one should look between 15,000 and 40,000 light years away from the core where there is just enough material around to build nice little planets. This is called by some the Galactic Habitable Zone (GHZ).
And right smack in the middle of the GHZ --- you'll never guess! --- revolves an ordinary, single yellow star with a tiny rocky planet that hosts the only known life in the universe.
Go out and have a look at the Milky Way tonight and be thankful for the perfect and awesome view we all share.
Questions or comments? Mark Ritter can be reached here.
Posted by Administrator at 2002.07. 6 02:45 PM | Comments (0)
