Free Astronomy Magazine March-April 2019

MARCH-APRIL 2019 What’s more, the star hosting GJ 3470b is only 2 billion years old, compared to the 4-billion- to 8-bil- lion-year-old star that planet GJ 436b orbits. The younger star is more energetic, so it bombards the planet with more blistering radia- tion than GJ 436b receives. Both are red dwarf stars, which are smaller and longer-lived than our Sun. Uncovering two evaporating warm Neptunes reinforces the idea that the hotter version of these distant worlds may be a class of transitory planet whose ultimate fate is to