Get the latest updates as we post them Ч right on your browser

. Last Updated: 07/27/2016

Exploring Otherworldly Worlds

You can go outside at night, even in Austin, and point at it and say Сthat star there has a planet around it,Т" said William Cochran of the University of Texas Astronomy Department. Epsilon Eridani, the star in question, is not especially bright, but it is very close: ThatТs why itТs visible to the naked eye. Nobody has found a star with planets that close to us before Ч but then, until 1995 nobody had found any stars with planets orbiting them at all.

Then astronomers developed techniques for detecting planets (though only very big ones) around other stars, and the flood gates opened. In the past five years, 40 new planets have been discovered, gas giants on the same scale as Jupiter, our own systemТs biggest planet. This week, at the International Astronomical UnionТs 24th general assembly in Manchester, England, another 10 have been revealed, including the planet found around Epsilon Eridani by CochranТs team.

"ItТs a very exciting discovery," explained Geoff Marcy of the rival planet-hunting team at the University of California at Berkeley, "[because] itТs only 10 light years away. In the next 100 or 200 years, it will be one of the first stars humans visit." And it is on planets, not stars, that we may find life more or less like ourselves.

Fifty new planets in only five years, all detected by cumbersome techniques that can only spot massive planets in relatively close, fast-moving orbits whose plane is more or less near to us Ч and each one took years of patient work to find. But the Berkeley team announced in Manchester that it had checked stars already known to have one planet Ч and in five out of 12 cases they found a second.

It begins to look like a universe where it is normal for a star to have a family of planets. While existing techniques still cannot discern smaller, rocky planets like our own around other stars, our solar systemТs familiar pattern of several gas giants in outer orbits and some smaller, more habitable planets nearer the sun also seem more and more likely.

So if suitable planets are as common as dirt, and life is not rare on them Ч where is everybody?

The puzzle has been growing ever since the Search for Extra-Terrestrial Intelligence project was set up in the 1970s. Every plausible frequency of the electromagnetic spectrum has been monitored more or less continuously for signs of intelligent life forms on other planets. The result? Silence. Either thereТs nobody intelligent out there, or theyТre not talking.

This raises three possibilities; each would have large implications for our view of our place in the universe.

One is that an intelligent species capable of producing high technology is not a normal evolutionary outcome, but a freakish event. In that case, there is a whole universe of friendly habitats with no intelligent natives out there waiting for us, and the human raceТs distant future could resemble the kind of "galactic empire" so beloved of early science fiction.

The second, darker possibility is that, while intelligent life crops up relatively often, it doesnТt last long: Species that develop technology wipe themselves out quite fast. That could explain the silence, for if the average survival time of a high-tech civilization is only a few hundred years, then even if there are tens of billions of suitable planets in our galaxy, there would on average be only one civilization (or none) in existence at any given time.

The third, darkest possibility is that there are indeed lots of intelligent species in the galaxy, but the smarter ones are keeping their heads down. If you have no idea whatТs out there Ч or if you know whatТs out there, and it scares you half to death Ч then the last thing you want to do is attract attention by broadcasting your position across the cosmos.

A fanciful speculation, but then all three of these options seem quite unlikely Ч yet one of them must be true. Our ignorance about the universe is still very great, and unless the human race wipes itself out, later generations will probably lump us together with the Ottomans and the Tang Chinese and the Roman empire as "dawn civilizations." But it is an interesting time to be alive.

Gwynne Dyer is a London-based independent journalist. He contributed this comment to The Moscow Times.