Blue Planet Discovered Where It Rains Glass

Astronomers have found a deep azure blue planet orbiting a star 63
light years away - the first time they've been able to determine the
actual color of a planet outside our solar system, NASA and the
European Space Agency said Thursday.

The planet, known as HD 189733b, is a gas giant with a daytime
temperature of 2,000 degrees Fahrenheit where it possibly rains liquid
glass sideways amid 4,500 mph winds, NASA says.

The blue color comes not from the reflection ofan ocean, as on Earth,
"but rather a hazy, blow-torched atmosphere containing high clouds
laced with silicate particles," NASA says.

"Silicates condensing in the heat could form very small drops of glass
that scatter blue light more than red light."

The space agencies said astronomers using the Hubble Space Telescope
discovered the planet in 2005 but only now have they been able to use
Hubble's observations to determinethe deep blue color.

The findings are in the August 1 issue of The Astrophysical Journal
Letters. To deduce the planet's color, astronomers measured how much
light was reflected off its surface.

They used the Hubble's Space Telescope to look at the planet before,
during and after it passed behind its star as it orbited.
"We saw the brightness of the whole system drop in the blue part of
the spectrum when the planet passed behinds its star," said Tom Evans
of the University of Oxford, the first author of the paper.

"From this, we can gather that the planet is blue, because the signal
remained constant at the other colors we measured."

The planet is only 2.9 million miles from its parent star, so close
that it is gravitationally locked, NASA says.

One side always faces the star and the other side is always dark. By
contrast, Mercury, the closest planet in our solar system to the sun,
is 29 million miles away from the sun at its closest.

In 2007, NASA's Spitzer Space Telescope measured the infrared light,
or heat, from the HD 189733b.

It showed day side and night side temperatures differ by about 500
degrees Fahrenheit, which should cause fierce winds to roar from the
day side to the night side, NASA said.

The atmosphere, the space agencies say, is changeable and exotic.

HD 189733b is in a class of planets called "hot Jupiters," which are
similar in size to the gas giants in our solar system but instead lie
very close to their parent star, the European Space Agency says.
"We know that hot Jupiters are numerous throughout the universe," the
ESA said in a statement.

"As we do not have one close to home in our own solar system, studies
of planets like HD 189733b are important to help us understand these
dramatic objects."