Tag: Doppler shift

No, SETI has not detected an alien signal from a Kepler planet

By Phil Plait | January 6, 2012 11:41 am

Last night, I started getting emails and tweets asking about a possible detection of a radio signal coming from two of the newly-discovered planets orbiting other stars.

Cutting to the chase: yes, a signal has been seen, but no, it’s not coming from some alien civilization. It’s almost certainly something much closer, like a satellite interfering with the observation.

So what’s the deal?


You talkin’ to me?

The Search For Extraterrestrial Intelligence (SETI) is a privately-funded group of scientists and engineers who are trying* an ongoing effort to figure out ways to detect signals from space that could be coming from other intelligences: aliens. They focus (haha) mostly on radio signals, since it’s very easy to send radio waves across the vast light years separating stars, it’s easy to detect radio waves (so primitive life like us can pick up the call), and it’s easy to encode information that way. Heck, we’ve been broadcasting coded radio waves for over a century now!

Currently, no unambiguous alien "Hello there!" has been detected. The sky is big, there are a lot of stars out there, and the radio spectrum is really wide, too. Think of how many radio stations there are on a typical radio dial from top to bottom; now divide that up into a billion tiny slices and try to find the one that’s playing the song you want to hear. It’s something of a painstaking process.

Recently, astronomers came up with a clever idea: the Kepler space mission is finding tons of planets orbiting other stars. It may find an Earth-like planet orbiting a Sun-like star at just the right distance to allow life to evolve, though no such planet has been found just yet. Still, why look all over the sky when we know where there are lots of planets?


Can’t stop the signal

So a search targeting those stars with planets has been set up. And that’s where our story picks up: using the ginormous 100 meter Green Bank Telescope, astronomers from UC Berkeley found what look like artificial signals when observing two different stars. The stars are called Kepler Object of Interest 812 and 817 (or just KOI 812 and 817 for short). Here’s an example of a signal they found from KOI 817:
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Wrong way planets screw up our perfectly good theories

By Phil Plait | April 13, 2010 11:00 am

Stupid reality, always mucking about with our ideas. How dare it!

In this case, reality is interfering with how we think planets form around stars. And the monkey in the wrench belongs to a handful of newly discovered planets that go around their stars the wrong way.

wrongwayplanet

That’s an artist’s illustration of one of these planets. As you can see in the diagram, the star rotates left-to-right, but the planet orbits right-to-left. That’s a bit of a puzzler, and here’s why.
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