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There's a Whole Lot of Space in Space
The Galaxy >
How close is the nearest star? Do you know? I have to fess up that this is kind of a trick question. If you are reading this during the day, it's a gimme. Just look outside and up; that big bright blinding ball in the sky is your answer. The sun is the nearest star to our planet.
Some of us who have taken an interest in astronomy may have assumed I was asking about the nearest star outside the solar system. Those astrophiles may have answered alpha Centauri, the brightest star in the constellation of Centaurus, shining brilliantly at a distant 4.4 light years.
That would have been almost correct. Actually alpha Centauri has a wee companion called proxima Centauri which is just a tad closer at about 4.3 light years. There's a free bonus fact for you.
But the point here and for the rest of this column today is that the nearest stars outside of our system are not just a stone's throw away; they are at very, very great distances --- light years, in fact!
A light year is about 6 trillion miles, the distance light can travel in a year. Once we humans hear numbers that huge, though, it gets pretty difficult to imagine. And this is the time when we nerdy science types try to think up some analogy to make it a little more real for all of us. Here goes ...
If you could fly a jet at 500 miles per hour it would take well over a million years to get to proxima Centauri, which would require nearly 4 million inflight meals. Yikes! Not a pretty thought. And that is just the one-way ticket!
But four light years is close compared to the average distance between stars. In our part of the galaxy, in our "neighborhood," the average distance between stars is about 7 light years. We need another model here to picture this.
If our sun were the size of a grapefruit, the next nearest grapefruit star wouldn't be in the same room, or even in California. It wouldn't be in Arizona, it wouldn't be in the Mississippi. The next nearest grapefruit star would be across the nation in Washington D.C.!
There is a whole lot of space in space!
Is this great distance between stars good or bad? Here's a hint: Next time Thanksgiving rolls around you'll have one more giant thing to be thankful for.
These great distances in stars are a great thing. We don't want them closer. To paraphrase another great star, "Vee vant to be alone."
More nearby stars would have disrupted the Solar System Building Project early on by inhibiting the development of unborn planets.
If the sun had gotten together with another star even after we were born, the other star would have severely interfered with our nearly perfect circular life-giving orbit. Worst Case Scenario has us being gravitationally slingshot out of that solar system altogether!
Moreover, if a nearby neighbor were a giant star, the lethal radiation from the explosive destruction of that short-lived monster would sterilize this planet in a flash.
On the other hand, a place in the galaxy with stars fewer and farther between is not good, either. We need those occasional big bad stars --- properly spaced --- to blow their guts out into space to provide the very material we need for planets, and for life.
These incomprehensible distances between stars are not too great, not too short --- they're just right.
Questions or suggestions? Write Mark Ritter here.
Posted by Administrator at 2002.10.26 02:23 PM | Comments (0)
