Terrified of Cosmic Loneliness? Astrobiologists Have a Dating Tip


This photo captured the transit of Venus across the sun on June 5, 2012. New research suggests that we should focus our search for extraterrestrial intelligence within Earth's transit zone. NASA/SDO, AIA
This photo captured the transit of Venus across the sun on June 5, 2012. New research suggests that we should focus our search for extraterrestrial intelligence within Earth's transit zone. NASA/SDO, AIA

Poor earthlings. You refuse to believe Earth is but a spark of life in a yawning, dead universe. You cling to the notion that aliens, somewhere, are dreaming of us, too. Will they hear our transmissions? Will they finally call us back? 

You need contact, but look: You're never gonna meet anyone with that sad panda attitude. Lucky for you, a new study to be published in the journal Astrobiology postulates exactly where in the observable universe we might find life.

As researchers René Heller and Ralph Pudritz point out, humans are their own best model of how intelligent life works — not only biologically, but methodologically as well. Look at one method humans use to seek aliens: They measure the dimming of starlight as a planet crosses in front of its host star during orbit. Astronomers may not be able to see the planet in question, but the resulting star dimming allows them to determine such key planetary life factors as illumination level and temperature.

Here's the thing, though: In order to view a planet in such a manner, you have to possess just the right vantage point in space.

Imagine someone sunbathing on a Manhattan rooftop. A lonely voyeur a block away is itching to train his telescope on such a scene, but he's only in luck if he has a direct line of sight between his window and that of the rooftop. If there's a billboard in the way or the viewing angle's too sharp, then he never sees a thing.

Earthlings, sorry, but you might be the voyeur in this scenario. There are so many rooftops, and you can't see them all. Similarly, you can only examine a planet in transit if you're in that planet's transit zone. You have to be in a position to observe the planet backlit by its own burning sun.

But here's the shred of hope: Aliens might be drastically different from us, but they still have to contend with the same properties of physical reality, as Heller and Pudritz remind us. They can only observe Earth in transit — and thus judge it a potential life-supporting world — if they exist within Earth's transit zone.

As Heller and Pudritz explain, that provides us with a potential cosmic dating pool of at least 100,000 stars — each with a possible smattering of planets and moons. They contend that this information allows us to focus our SETI pursuits, transmitted missives and deep eavesdropping efforts toward the like-minded voyeurs who just might be viewing, listening and signaling us back.