WASP-12b a “Blistering Pitch-Black Planet”.

NASA has put out a press release about Hubble Space Telescope observations of WASP-12b. Taylor Bell et al find that WASP-12b “traps at least 94 percent of the visible starlight falling into its atmosphere”, making it “as black as fresh asphalt”.

WASP-12b “as black as asphalt” (Credit: NASA, ESA, and G. Bacon, STScI)

The article explains that WASP-12b, in a very close, 1.2-day orbit, is so irradiated by its host star that “clouds probably cannot form to reflect light back into space. Instead, incoming light penetrates deep into the planet’s atmosphere where it is absorbed by hydrogen atoms and converted to heat energy”. NASA’s press release has led to coverage on several dozen websites.

WASP-12b is one of the more important of the WASP discoveries, with over 30 refereed papers so far focused on understanding it. Most notably, the fierce stellar irradiation means that material is boiling off the planet and forming a cloud surrounding it.