ANALYSIS: Quarter of Sun-Like Stars Host Earth-Size Worlds
When HD 189733b slipped behind the star, the light seen by Hubble dropped deeply into the blue part of the electromagnetic spectrum, while all other colors remained the same, a telltale sign of the planet's color.
HD 189733b is far too hot for liquid water, but there are other molecules that could scatter blue light, mirroring what happens in Earth's atmosphere. Scientists believe HD 189733b has clouds made of liquid glass.
"Our best guess is that the color is due to a combination of reflection by silicate clouds and absorption by sodium atoms," astronomer Frederic Pont, with the University of Exeter in the United Kingdom, wrote in an email to Discovery News.
"Other factors may be photochemical aerosols -- i.e. smog -- and absorption by other atoms or molecules than sodium," though presently are no specific candidates," he added.
ANALYSIS: 'Earth-like' Planets May Be Nothing Like Earth
Driving the planet's extreme environment is its unenviable position 30 times closer to its parent star than Earth orbits the sun. At that distance, surface temperatures reach more than 1,800 degrees Fahrenheit.