Kepler-438b is only 12 percent bigger than Earth in diameter, and scientists gave it a 70 percent chance of being rocky like our own world. Scientists were further tantalized by its distance from its host star, Kepler-438. Kepler-438b is a red dwarf chillier than our own sun, but the exoplanet in question is close enough to its star that it boasts a 70 percent chance of holding liquid water -- or having the right temperature to hold it, anyway.
But it turns out that the star is ejecting superflares 10 times as powerful as any solar flare ever recorded in our own system. The flares carry the energy of 100 billion megatons of TNT, and they happen regularly, at least once every few hundred days.
Not exactly a pleasant vacation spot.
The real concern is that these flares might carry coronal mass ejections with them. When our own sun flares up, it sends out bursts of plasma and magnetic field. Our own planet's magnetic field protects us from most of the ill effects of such energetic particles, but others might not be so lucky. In fact, research now indicates that Mars lost its lush, warm climate of old because it lacked the magnetic field to protect itself from the sun's emissions.
"If the planet, Kepler-438b, has a magnetic field like the Earth, it may be shielded from some of the effects," lead researcher David Armstrong of the University of Warwick said in a statement. "However, if it does not, or the flares are strong enough, it could have lost its atmosphere, be irradiated by extra dangerous radiation and be a much harsher place for life to exist."
With no atmosphere and a violent host star, Kepler-438b would quickly become a pretty scary place to be. It would be barren and airless, subjected to the intense radiation of its sun's ongoing flares.
It's likely that most "Earth-like" planets will disappoint scientists. But since NASA estimates that there are a billion such planets in our galaxy alone, at least there are still plenty of options.
Correction: A previous version of this post referred to the planet as "radioactive" when "irradiated" is more accurate.