Astronomers make landmark planet color discovery

LONDON — Astronomers have for the first time managed to determine the color of a planet outside the solar system, a blue gas giant around 63 light years away.

An international team of astronomers working with the Hubble Telescope made the discovery observing HD 189733B, one of Earth’s nearest planets outside the solar system.

Frederic Pont of the University of Exeter in England said Friday that “measuring the planet’s color is a real first — we have never managed it before with a planet outside our own solar system.”

While Earth looks blue from space because of its oceans, the astronomers claim the gas giants’ color was created by a hazy turbulent atmosphere of silicate particles that scatter blue light.

To ascertain the planet’s color, the astronomers measured the amount of light reflected off its surface as it eclipsed its host star.

HD 189733B belongs to a class of giant gas planets called “hot Jupiters” that orbit close to their parent stars, and has an atmosphere temperature of around 1,000 C (1,832 F).

The heat on the planet causes rocks to evaporate and glass to rain sideways in howling 4,500 mph (about 7,250 kph) winds.

Astronomers chose the particular planet for observation because of its proximity to Earth, and size in relation to the host star which it orbits.

Pont said the technology the astronomers used had pushed the Hubble Telescope’s abilities to the limit given the distance and light from other stars obscuring their view.

“People keep coming up with a better ways of viewing planets indirectly so I’m sure the technology will eventually improve,” Pont said.