The sad fate of a demoted, briefly Earth-like exoplanet

Of the 1235 possible planets discovered by NASA's Kepler telescope, one of the most exciting was KOI 326.01, which appeared to be roughly Earth's size and temperature. But it turns out the planet's habitability is just a big clerical error.

It's all because the planet's star isn't as bright as astronomers thought. Its star, KIC 9880467, is located very close to another star. A reference catalog used by the Kepler astronomers listed KOI 326.01's star as the brighter of the two, but some cursory double-checking quickly revealed that that's not the case. The other star is much, much brighter, and that throws off all the calculations for the size and temperature for KOI 326.01.

In fact, Kepler astronomer Natalie Batalha says it's not even clear which of the two stars the planet is actually orbiting. If it is KIC 9880467 after all, then the planet must be bigger and hotter than previously thought, and its position relative to such a dim star would place it squarely outside the habitable zone. If it's the other, far brighter star, then KOI 326.01 would go from a little too warm to boiling hot.

And so KOI 326.01's run as a prospective new Earth is over before it even started. That said, this new finding shouldn't be taken as a broader rejection of Kepler's findings - the telescope's mission is primarily statistical, and its job is to determine what percentage of stars have planets and what the demographics of those solar systems look like. Sure, it's disappointing to lose a potentially Earth-like planet, but that's why these are just planet candidates, and not the confirmed, genuine article.

Indeed, KOI 326.01 was initially classified as only a "moderate probability candidate", meaning there was at least a 20% chance the planet would turn out to be a false positive, which is far worse odds than hundreds of other candidates in the study. If nothing else, this whole episode is a reminder that, when in doubt, make sure your star reference catalogs are up-to-date. That's a lesson I think we can all take away from this.

Via 80 Beats.