Dense, Dark and Hot

Spitzer has done something amazing.

No, not the Governor of New York, although that Spitzer did recently nominate a new Executive Director of the New York State Foundation for Science, Technology and Innovation.

Rather, we’re talking about the first map of an extrasolar planet, HD 189733b, a "hot Jupiter" planet — and the hottest planet yet observed in the universe — which is located approximately 60 light-years from Earth.

The planet is so hot that astronomers believe it’s absorbing almost all of the heat from its star, and reflecting almost no light and thus making its appearance black, as this artist’s rendition of the planet illustrates:


(Live animations of the picture above can be found here.)

NASA explains the mapping project and the resulting discoveries: 

 Roughly 50 of the more than 200 known planets outside our solar system, called exoplanets, are hot Jupiters. Visible-light telescopes can detect these strange worlds and determine certain characteristics, such as their sizes and orbits, but not much is known about their atmospheres or what they look like.

Since 2005, Spitzer has been revolutionizing the study of exoplanets’ atmospheres by examining their infrared light, or heat. In one of the new studies, Spitzer set its infrared eyes on HD 189733b, located 60 light-years away in the constellation Vulpecula. HD 189733b is the closest known transiting planet, which means that it crosses in front and behind its star when viewed from Earth. It races around its star every 2.2 days.

Spitzer measured the infrared light coming from the planet as it circled around its star, revealing its different faces. These infrared measurements, comprising about a quarter of a million data points, were then assembled into pole-to-pole strips, and, ultimately, used to map the temperature of the entire surface of the cloudy, giant planet.

The observations reveal that temperatures on this balmy world are fairly even, ranging from 650 degrees Celsius (1,200 Fahrenheit) on the dark side to 930 degrees Celsius (1,700 Fahrenheit) on the sunlit side. HD 189733b, and all other hot Jupiters, are believed to be tidally locked like our moon, so one side of the planet always faces the star. Since the planet’s overall temperature variation is mild, scientists believe winds must be spreading the heat from its permanently sunlit side around to its dark side. Such winds might rage across the surface at up to 9600 kilometers per hour (6,000 miles per hour). The jet streams on Earth travel at 322 kilometers per hour (200 miles per hour).

"These hot Jupiter exoplanets are blasted by 20,000 times more energy per second than Jupiter," said co-author David Charbonneau, also of the Harvard-Smithsonian Center for Astrophysics. "Now we can see how these planets deal with all that energy." 

As Wired points out,  Spitzer’s technology could be used to map Earth-like planets — like the recently-discovered Gliese 581c, which we wrote about here.

For more on the Spitzer Space telescope, check out this great video found in the motherlode of online video, aka YouTube: