The other Pale Blue Dot

While our Earth is the original Pale Blue Dot, as imaged from Voyager 1 in 1990. Scientists have recently found another blue planet. Actually, it’s more a cobalt blue. I didn’t know about it until I read today’s XKCD comic. This planet is called HD 189773 b. This planet is a gas giant. Astronomers were able to figure out its color by looking at how the color of the host star changed when the planet went behind it. The blue colors dimmed when the planet was hidden from us. Thus, the blue planet must be blue. Cool.

Further, the probable reason it’s blue is that the atmosphere is mostly sodium, which absorbs red light. The temperature is around 1000 °C, with a variance of about 250 °C from day to night. This would make it have very strong winds, up to around 7000 kph. Temperatures this high would also cause the silicates to form glass, which would scatter blue in visible light. This planet is blue with winds over 7000 kph, and glass clouds. Now that’s cool.