The discovery of planets orbiting other stars continues apace. Science nerds love this stuff, but I've come to find it very silly and more than a little disturbing.

The theory that our own planetary system developed out of a cloud of dust and gas dates back, you may be surprised to learn, more than 200 years. The theory is now fairly well developed, though of course it's developed using mathematical models. Nobody actually gets to watch the process happening, because there would be nothing to see until after the planets had formed, and anyway it takes millions of years. Nonetheless, it's not at all surprising that many stars (quite likely most of them) are orbited by planets. That some of those planets would have about the same mass as Earth and would orbit in the "Goldilocks zone" of temperature where water is a liquid is not at all surprising.

It's nice that we now have telescopes powerful enough to do some research in this field. What disturbs me is the unexamined spiritual aura around the search. It's not enough that we find balls of rock -- no. We're searching for planets that may have life.

Let's take a step back and examine what that means.

Life is a chemical process. It's just molecules. So any planet that has the right temperature and combination of ingredients (plenty of water, plenty of carbon, nitrogen, magnesium, and so forth) and that isn't rendered uninhabitable by meteor bombardment will quite likely support living organisms, or living processes if you prefer. And ... so what?

In the first place, we're never going to go there. Nor will our great-grandchildren ever have the opportunity. Space is simply too vast and the available methods of transportation too slow, too expensive, and too dangerous.

But it's worse than that. What we now understand about our own planet is that life has existed here for at least 2.5 billion and possibly 3 billion years. And what we know about this is that for the first 2 billion of those years, life consisted entirely of single-celled organisms. Toward the end, maybe a few worms crawling along in the mud at the bottom of some shallow ocean, but basically we're talking about organisms that would be too small to see with the naked eye, except in large clumps.

For most of the history of our own planet, if a space-faring alien race had happened to drop in for a visit, they would have found ... pond scum. That's it. Pond scum. Not an inspiring prospect, is it? Even if you could fly off to a planet orbiting another star, and even if you had chosen one that almost certainly harbored life, why would you want to visit a place where the big tourist attraction was pond scum?

And then, 500 million years ago, came the Cambrian revolution. Multi-celled life! Zowie! So our imaginary aliens drop in for a visit, and what do they find? A planet overrun by trilobites. Trilobites everywhere, little multi-legged critters crawling over one another, scuttling around in the water, and probably nothing on land but bare rock.

The search for exoplanets that support life is really no more than a Star Trek fantasy. There's nothing out there that would genuinely be of any interest, except to science geeks like you and me.

Instead of spending millions on these sophisticated instruments and more millions in salaries to the staff that examines the data the instruments scrape up, why not spend the money trying to make sure our own planet remains habitable?

There is no Planet B, folks. There's no place like home. We're stuck here, and our descendants will be stuck here quite likely for as long as there are any of them. If we don't take care of this planet, when our interstellar visitors finally come to visit they'll probably find nothing but pond scum. And maybe cockroaches. I expect the cockroaches will do all right. We probably don't have the power to actually bring about the end of life on Earth, but we're certainly on track to destroy every single species of land-dwelling vertebrate.

We humans quite regularly go haring off after bizarre irrelevancies. The Crusades were not an aberration. We have a real hard time keeping our eye on the ball.

The Earth is the ball. Maybe we could figure out how to keep an eye on it, rather than gazing off into blazing infinity. Fiddling while Rome burns.