My interview with an alien hunter


Kepler-62f with 62e as Morning Star, Image credit: NASA Ames/JPL-Caltech/Tim Pyle

On January 6, the world learned of eight new exoplanets – that is, planetary bodies orbiting stars other than the sun – existing somewhere deep in our universe. And of these newly discovered planets, one lying some 470 light-years away appears to be more Earth-like than any previous contender. The planet called Kepler 438b, though a little uninspired as far as names go, is where scientists are pinning their hopes. Why exactly? For starters, this potential Earth twin may have a rocky surface and even liquid water – two key features that render our planet so suitable for life.

But however monumental – even earth-shattering, these findings have managed to be eclipsed by a host of more terrestrial matters like who wore it best at the Golden Globes.  So, I wondered, are we missing the big picture here?  The real BIG picture?  How does a discovery of this magnitude so quickly slip from our species’ consciousness?

Shostak, Seth_2 for 8_5 x 11 paper

Dr. Seth Shostak, Senior Astronomer and Director, Center for SETI Research

In search of a little perspective, I turned my questions to astronomer Dr. Seth Shostak.  His business card may read, “Director of the Center for SETI Research,” but Shostak will answer just as quickly to “alien hunter.”  Surely, this cosmic news made more than a mere blip on his radar.

Dr. Shostak, from a scientific perspective, how significant are these findings? 

By now, many people are inured to announcements of new planets, and indeed, it’s no longer the big news it once was.  But one should always keep in mind the big picture here: this work is leading inexorably to a reasonably precise answer to the question, “What fraction of stars have planets that could support life?”  And that’s a very interesting question, indeed.

What is the next step in better understanding these planets?

What you really want to do is construct a telescope that can actually SEE such planets — to have enough sensitivity and ability to block out the light from a planet’s sun enough to image the planet.  The planet need be no more than just a dot in a photograph.  But by taking that light and sending it through a spectroscope, a souped-up kind of prism, we might detect water vapor in the planet’s atmosphere, or possibly even oxygen or methane.  Finding one of the latter two gases would be a strong clue that the planet has life.

Do we currently possess the technology to determine whether or not they support life?

We’re just on the edge of being able to do what’s described above: spectroscopically sniffing the atmosphere of an exoplanet.  We can possibly do it today in a few cases, but only a few.  However, within a decade or so, we’ll have instruments that extend this list ten-fold or more.  Our inventory of exoplanets that sport life will then begin … assuming that biology is commonplace.

How would you explain the probability of extraterrestrial life to those who doubt its existence?

There are a trillion planets just in our galaxy, and maybe one in ten or twenty would be suitable for life.  If Earth is the only world in the Milky Way with a bit of biology, then our planet is a miracle.  As a scientist, I’m disinclined to believe in miracles.

Do you think it is more likely that we will discover extraterrestrial life before it discovers us?  Why or why not?

There could be many societies in the depths of space that know about life on Earth.  Photosynthesis has filled our atmosphere with oxygen, and that’s a “signal” that Earth has been sending into space for two billion years.  But as far as intelligent life is concerned, I think it likely that we’ll find it before it finds us.  If the nearest aliens are 500 light-years away, they won’t yet have received any of our radio signals.  But we could receive theirs tonight or tomorrow if they’ve been on the air for a while.

As a self-proclaimed “alien hunter,” what are some of the exciting things you do while working at the SETI Institute?

Thinking about how we could improve our search for cosmic company: where should we point our antennas, and what new instruments might improve our chances of finding a signal.  I also greatly enjoy bringing science to the public via our weekly radio show, “Big Picture Science.”  We get a lot of reaction to that.