But that's where the comparison ends, they said. On this distant world the daytime temperature is nearly 2,000 degrees Fahrenheit with howling 4,500-mph winds.
The cobalt blue color comes not from the reflection of sunlight off oceans as it does on Earth, but rather from a hazy, blow-torched atmosphere containing high clouds laced with silicate particles, a NASA release said Thursday.
Silicates condensing in the heat could form very small drops of glass that scatter blue light more than red light, astronomers said.
The distant blue planet dubbed HD 189733b is among a bizarre class of planets called hot Jupiters, which orbit precariously close to their parent stars, and the Hubble findings provide new insights into the chemical composition and cloud structure of this class of exoplanets, scientists said.
"We obviously don't know much on the physics and climatology of silicate clouds, so we are exploring a new domain of atmospheric physics," science team member Frederic Pont of Britain's University of Exeter said.