An artist's impression of a fluffy planet orbiting a red dwarf star. (NOIRLab/NSF/AURA/J. da Silva/Spaceengine/M. Zamani) If exoplanet research is to be believed, the Milky Way galaxy could be like some sort of fantastical candy-land. First, there was the discovery of exoplanets with the density of cotton candy. Now, astronomers say they've discovered a world that is comparable to the density of marshmallow. It is, they say, the fluffiest exoplanet discovered to date orbiting a red dwarf star. This is important. It means that worlds with significant gas envelopes can be found closely orbiting the small, tempestuous dwarf stars, which...