Really. Where are all the aliens? We should have been probed, exterminated, assimilated, infected, invaded or abducted by now, shouldn’t we?
The Fermi Paradox ponders the lack of evidence of another transmitting intelligent civilization — of all the stars and all the galaxies in the universe, you’d think one intelligent alien race would have bothered to call by now? Either we’re on the interstellar “do not call” list, or we’re the most advanced life form out here (scary thought), or (even scarier) we’re the only life form out here.
- 17 percent of the stars surveyed by NASA’s Kepler space telescope have Earth-sized worlds in orbit, underlining the preponderance of small exoplanets in our galaxy. DAVID A. AGUILAR (CFA)
The search for any extraterrestrial life is one of the most profound things we, as a species, can do. But as any other life beyond Earth’s shores has yet to be discovered, the search for extraterrestrial intelligence (SETI) can be a hard-sell. Still, the search continues and scientists are thinking up more and more extreme ways to fine-tune our high-tech array of astronomical instruments to detect intelligence in the stars.
Here are the weird and wonderful ways scientists hope to snare an intelligent alien.
Kepler’s SETI Candidates
The main assumption we have to make is that our hypothetical alien neighbors have evolved in a similar way to us. Because there’s a lack of other examples in the cosmos (so far) it’s a pretty good place to start and a logical assumption to make — even though it might be wildly improbable. I’m skeptical that any other galactic race evolved through the “reality TV phase.”
One phase of development we assume is that an intelligent race of aliens will have worked out how to transmit radio waves. We’ve been “radio loud” for nearly 120 years (although, with the advent of digital, our easily detectable analog signal will soon go silent) — so should any eavesdropping aliens be within 120 light-years from Earth, they may have detected us.
But that’s just accidental radio leakage — what if we could turn our radio antennae to the stars and “listen” for ET’s deliberate attempt to send a radio signal? Since the 1960’s SETI programs have hunted for alien radio signals, but only recently, with the help of NASA’s Kepler space telescope, have we been able to carry out directed searches on star systems that are known to contain exoplanets that could play host to an alien civilization. Although this directed SETI hasn’t turned up a signal yet, there’s potentially millions more “habitable” worlds out there — we’ve only just begun.
The radio signal detected by the 100-meter Green Bank Telescope in West Virginia while scanning the exoplanetary candidate KOI 817. This is the kind of signal SETI scientists would expect to find if an alien civilization is transmitting. UC BERKELEY/SETI
There have been a few false alarms when listening out for a SETI signal. As we’re looking for a specific, narrow-band radio signal (something that could only be generated by a form of technology), terrestrial interference can show up in SETI searches. Fortunately, astronomers are a savvy bunch and usually know the difference between aliens and Aunt Sally gossiping on her cellphone.
Alien Footprints… on the Moon?
- Apollo footprints and equipment are still visible on the lunar surface. NASA
- NASA’s Mars Phoenix lander as seen from orbit. NASA/JPL-CALTECH
HP 56948 — Sun’s “Twin”
- Artist’s impression of HP 56948. ESO
- Transits of artificial shapes across the face of stars can reveal their shape to the Kepler space telescope. LUC F. A. ARNOLD/OBSERVATOIRE DE HAUTE-PROVENCE IN PARIS
From Kepler’s vantage point, as it observes the slight “dip” of light it receives from a star as an accompanying world passes in front (or “transits”), the space telescope can analyze the “light curve” it records. Although planets are, you know, circular, there may be a surprise if the light curve reveals that an irregular shape has just passed in front of a star. Irregular planetary shapes do not exist in nature, so if Kepler detected anything other than a circle — a massive pyramid, perhaps — that could be evidence of alien shenanigans.
Where Did That Star Go?
- The spiral galaxy M51 — see any bubbles of darkness? NASA, ESA
- Asteroids in orbit around a star — could alien mining activities be detected? NASA
Black Hole Starship Engines!
- Black holes. To power spaceships. Why not? NASA
Did That Alien Flash Us?
- Any beacons out there? ESO
- A female bottlenose dolphin at the U.S Navy’s Marine Mammal Research Program. WIKIMEDIA COMMONS
- Quiet galaxy… green aliens? NASA
- “Surf’s up dude! Ah, no. It’s an alien invasion.”COLUMBIA PICTURES