Once-hyped planet does not exist


In 2010, I told you about Gliese 581g, a potentially habitable exoplanet that astronomers thought they had spotted orbiting a star more than 20 light years from Earth.

Turns out, they are most likely wrong about that.

The existence of Gliese 581g has been shaky for a while — other scientists were questioning the first team's data just a few weeks after the initial announcement.

Now, writes Matthew Francis at The Daily Beast, the opposing scientists have put together a damning case against Gliese 581g's existence, enough that it's now reasonable to say that what we thought was an exoplanet was never anything more than a blip in the data.

A new study, published in the journal Science, showed that what seemed to be the sign of a planet was more likely to be from the star's "weather"—the same sort of magnetic fluctuations that cause prominences and sunspots on the Sun. Not only that, but a second planet in the same system, Gliese 581d, probably doesn't exist either, for the same reasons.

Your first response may be to say, "Stupid scientists! How could they get this so wrong?!" (You aren't a very nice person, you know.) But that's a mistake. The story of Gliese 581g highlights how hard exoplanet-hunting is, and how science at its best is self-correcting. All results have to be taken as tentative at first; if they survive under scrutiny or (ideally) replication by other researchers, we can trust them. It's often messy or slow and can lead to ego clashes, but it's how science works.

That is a good description of how science works. But it's also important to remember the ridiculous level of hype that came with the initial announcements about Gliese 581g. At the time, Stephen Vogt, the lead author on the paper about the would-be exoplanet, told a press conference that, "My own personal feeling is that the chances of life on this planet are 100 percent."

And many, many news outlets ran with that as the story. Now, like Vogt, they are wrong, too. But, unlike the scientific record, human memory isn't self-correcting. And what version of this story is the average person more likely to remember?

So, yes, I agree with Matthew Francis that Gliese 581g is a great example of how the process of science can catch and correct mistakes. But it's also a great example of how science can be hyped in ways that undermine that process outside the halls of academia.