Another Exoplanet - When Will the Search End?

The American Astronomical Society announced the discovery of the first "exoplanet" (outside our solar system) that is small and rocky, instead of a gas giant.

Someone at the annual meeting called the discovery "among the most profound in human history."

Goodness! Let's not get carried away, shall we?

Only a few years ago, it was widely believed that it was impossible to verify the existence of a distant star's planet. Then someone figured out how to do it! Now there's a lot of excitement in the world of science and a lot of money being spent to discover more exoplanets. If it's possible to ask a practical question with all this celebrating going on, how about this: When is enough enough? When do we stop searching?

Hundreds of exoplanets have been discovered so far, and they claim there are billions of planets in our galaxy alone. Do we stop at 1,000? 10,000? At 100,000? Do we stop searching after a million exoplanets have been identified? That would still leave billions and billions of undiscovered planets.

The best explanation of the value of the current effort is that it's teaching us more about the nature of planets and how they form.

Another reason we hear about is the search for life beyond our planet. Do we continue searching because we hope to find a planet that's ideal for supporting intelligent life?

We might find such a rocky planet in a star's "habitable zone," meaning it's far away from its star (but not too far) to allow liquid water to exist. But how young would the planet be? Asteroids rain down on young planets. Does it have an electromagnetic field to protect life from deadly solar radiation (Mars, for example, does not)? Does it wobble erratically on its axis? Does it have an eccentric orbit? How evolved would the life be? It's impossible to know these things without going there.

The latest exoplanet, the one everyone is so excited about, is 560 light years away. Considering that our galaxy is 100,000 light years across, 560 light years is pretty close. Scientists say this newly discovered planet is not a candidate. It's too hot (thousands of degrees) to support life.

But say a true Earth-like planet were discovered only 560 light years away, and we had an amazing space craft that could blaze through space at a million miles per hour (20 times faster than the fastest spacecraft in history). At this speed it would take our space travelers 3,880 centuries to make the trip - one way. To put that into perspective, Jesus Christ walked the Earth only 21 centuries ago.

So the search for extra-terrestrial life is not a valid reason for continuing to scan the heavens for distant planets. Yes, intelligent life probably is out there somewhere, or once was. But we will never know. I know it's not fashionable to say so, but it truly is too far to go. Once you run the numbers, you grasp this simple, practical fact.

And so, all the romance about "our destiny" as explorers aside, I ask again: How many exoplanets do we have to discover before it no longer makes sense to continue?

Post by Dennis E. Coates, Ph.D., Copyright 2010. Building Personal Strength . (Image courtesy of NASA)