A Refinement for SETI

 SETI is a branch of astronomy that seeks direct detection of alien life. We can currently only visit the other planets of our solar system, and none appear to have any intelligent beings on them. Therefore, SETI, which stands for Search for Extraterrestrial Intelligence, looks for radio signals from other civilizations. While we have detected a few signals we can’t yet explain, they were only one-time events and likely come from some as-yet unknown natural physical process.

We have been broadcasting our own radio signals into space for about 100 years, so any civilization within 100 light-years of us could potentially detect our existence. With our current technology, we can detect any civilization with our own level of radio signals from twice that distance. A civilization with more advanced radio technology might be detected by us from even farther away.

At our current level of technology, it is nearly impossible for us to determine if any signal we might receive originates from the star itself or an orbiting planet. The separation is generally too small for our equipment to distinguish between the two. Any signal we do detect is far more likely to be caused by a natural process in the star and not from a civilization on an orbiting planet unless we can determine it came from the planet.

The Beta Pictoris system with Beta Pictoris b. Credit ESO

The star Beta Pictoris lies only 63.4 light-years from us. In 2008, astronomers discovered it has a planet, Beta Pictoris b. It is a massive gas giant planet, ten times more massive than Jupiter. Recently, astronomers discovered a radio signal emanating from that star system, but they couldn’t tell if it came from the star or its orbiting planet. A team of scientists led by Kevin Ortiz Ceballos at the Center for Astrophysics, Harvard & Smithsonian found a clever way to determine the source using the MeerKAT Radio Telescope Observatory in Australia.

MEERKAT Observatory. Credit Universiay of Manchester

They overlaid a map of distant quasars, the active black holes at the center of virtually all galaxies, over the Beta Pictoris system. Using the well-established positions of the quasars, they could determine that the radio emissions came from a point just beside the star, proving the emissions came from the planet. They determined the signals resulted from aurora, like our Northern Lights, but much stronger due to Beta Pictoris b’s much more powerful magnetic field.

Suzanne Aigrain, a professor of astrophysics at the University of Oxford, who was not involved in the study, said, "Astronomers have been looking for radio signals from exoplanets for some time. There have been tentative, indirect detections before, but this is the first truly convincing direct detection, and it hopefully paves the way for many more."

We didn’t discover aliens, but we have found a way to distinguish whether any signal we do detect comes from a star or one of its planets, and therefore possibly from an alien civilization.

  

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.