Scientists Determine Blue Is Color of Distant Planet

[Vikrant]

For the first time, astronomers have discovered the true color of an alien planet orbiting another star—a deep azure blue like Earth seen from space—an international research team said Thursday.

Using the Hubble Space Telescope, the researchers analyzed the spectrum of visible light from a planet known officially as HD 189733b, which orbits a faint star about 63 light years away. This immense blue world—among the closest and most well-studied of the hundreds of exoplanets discovered in recent years—is a hazy hothouse swept by blow-torch winds where it regularly rains molten glass.

For their analysis, the scientists used the Hubble’s imaging spectrograph to measure visible light from the star and planet together, and then measured the light from the system when the planet passed behind the star and was hidden from observers on Earth. To isolate the planet’s light, they subtracted one from the other.

The wavelength of the missing light corresponds to a visible shade of blue, and that is the color of the light reflected by the planet, the astronomers reported in the upcoming August issue of the Astrophysical Journal Letters.

“We inferred the color,” said astrophysicist Tom Evans at the U.K.’s University of Oxford, who led the study. By knowing the wavelength, “we can imagine the color the planet would have if we could look at it with our own eyes.”

As viewed from space, the planet Earth is itself a vibrant blue because of its oceans, which absorb red and green wavelengths more strongly than blue ones. Some blue wavelengths of sunlight also are selectively scattered by oxygen and nitrogen molecules in the air. Mars, in turn, appears red to the eye because its rusty surface is rich in iron oxide that absorbs the blue and green wavelengths of the light spectrum while reflecting the red wavelengths.

But the blue color of HD 189733b arises solely from the interplay of light in its super-heated atmosphere. Based on earlier measurements, scientists believe that the planet’s exotic air is laced with grains of silicate, a common component of beach sand, whipped up in high clouds by winds that average more than 4,000 miles an hour.

In an atmosphere where the temperature appears to hover at 1,000 degrees Celsius, these silicate particles melt to make “raindrops” of glass that scatter visible blue light more than red light, the scientists reported. Consequently, the orb would appear blue because of its reflected light, but the planet is too far away for its hue to be seen directly with existing telescopes.

“We are really pushing the limits of what we can measure,” said Mr. Evans.

Scientists Determine Blue Is Color of Distant Planet - Wall Street Journal - WSJ.com

 

[BlueGin]

For the first time, astronomers have discovered the true color of an alien planet orbiting another star—a deep azure blue like Earth seen from space—an international research team said Thursday.

Using the Hubble Space Telescope, the researchers analyzed the spectrum of visible light from a planet known officially as HD 189733b, which orbits a faint star about 63 light years away. This immense blue world—among the closest and most well-studied of the hundreds of exoplanets discovered in recent years—is a hazy hothouse swept by blow-torch winds where it regularly rains molten glass.

For their analysis, the scientists used the Hubble’s imaging spectrograph to measure visible light from the star and planet together, and then measured the light from the system when the planet passed behind the star and was hidden from observers on Earth. To isolate the planet’s light, they subtracted one from the other.

The wavelength of the missing light corresponds to a visible shade of blue, and that is the color of the light reflected by the planet, the astronomers reported in the upcoming August issue of the Astrophysical Journal Letters.

“We inferred the color,” said astrophysicist Tom Evans at the U.K.’s University of Oxford, who led the study. By knowing the wavelength, “we can imagine the color the planet would have if we could look at it with our own eyes.”

As viewed from space, the planet Earth is itself a vibrant blue because of its oceans, which absorb red and green wavelengths more strongly than blue ones. Some blue wavelengths of sunlight also are selectively scattered by oxygen and nitrogen molecules in the air. Mars, in turn, appears red to the eye because its rusty surface is rich in iron oxide that absorbs the blue and green wavelengths of the light spectrum while reflecting the red wavelengths.

But the blue color of HD 189733b arises solely from the interplay of light in its super-heated atmosphere. Based on earlier measurements, scientists believe that the planet’s exotic air is laced with grains of silicate, a common component of beach sand, whipped up in high clouds by winds that average more than 4,000 miles an hour.

In an atmosphere where the temperature appears to hover at 1,000 degrees Celsius, these silicate particles melt to make “raindrops” of glass that scatter visible blue light more than red light, the scientists reported. Consequently, the orb would appear blue because of its reflected light, but the planet is too far away for its hue to be seen directly with existing telescopes.

“We are really pushing the limits of what we can measure,” said Mr. Evans.

Scientists Determine Blue Is Color of Distant Planet - Wall Street Journal - WSJ.com

I was just going to post this in the space exploration thread. Pretty cool. Can't even imagine a place that has 4000 mile an hour winds and raindrops of molten glass. Interesting article.

 

[Vikrant]

^ Sounds like a fun place I guess the blue color got us all excited but rest of the stuff does not seem very exciting at least to me.

 

[freedombecki]

Blue diamonds are pretty nice.

However, the article at NASA on July 11 has this to say:

RELEASE: 13-202
NASA'S HUBBLE FINDS A TRUE BLUE PLANET

​

WASHINGTON — Astronomers making visible-light observations with NASA's Hubble Space Telescope have deduced the actual color of a planet orbiting another star 63 light-years away.
The planet is HD 189733b, one of the closest exoplanets that can be seen crossing the face of its star.
Hubble's Space Telescope Imaging Spectrograph measured changes in the color of light from the planet before, during and after a pass behind its star. There was a small drop in light and a slight change in the color of the light. "We saw the light becoming less bright in the blue but not in the green or red. Light was missing in the blue but not in the red when it was hidden," said research team member Frederic Pont of the University of Exeter in South West England. "This means that the object that disappeared was blue."
Earlier observations have reported evidence for scattering of blue light on the planet. The latest Hubble observation confirms the evidence.
If seen directly, this planet would look like a deep blue dot, reminiscent of Earth's color as seen from space. That is where the comparison ends.
On this turbulent alien world, the daytime temperature is nearly 2,000 degrees Fahrenheit, and it possibly rains glass — sideways — in howling, 4,500-mph winds. The cobalt blue color comes not from the reflection of a tropical ocean as it does on Earth, but rather a hazy, blow-torched atmosphere containing high clouds laced with silicate particles. Silicates condensing in the heat could form very small drops of glass that scatter blue light more than red light.
Hubble and other observatories have made intensive studies of HD 189733b and found its atmosphere to be changeable and exotic.
HD 189733b is among a bizarre class of planets called hot Jupiters, which orbit precariously close to their parent stars. The observations yield new insights into the chemical composition and cloud structure of the entire class.
Clouds often play key roles in planetary atmospheres. Detecting the presence and importance of clouds in hot Jupiters is crucial to astronomers' understanding of the physics and climatology of other planets.
HD 189733b was discovered in 2005. It is only 2.9 million miles from its parent star, so close that it is gravitationally locked. One side always faces the star and the other side is always dark.
In 2007, NASA's Spitzer Space Telescope measured the infrared light, or heat, from the planet, leading to one of the first temperature maps for an exoplanet. The map shows day side and night side temperatures on HD 189733b differ by about 500 degrees Fahrenheit. This should cause fierce winds to roar from the day side to the night side.
For more information about the Hubble Space Telescope, visit:
http://www.nasa.gov/hubble
​

 

[itfitzme]

When are we going to find something cool and wet?

Geez....

 

[Vikrant]

^ I am pretty sure there are some cool and wet planets out there. I just am not sure if they are within our reach of observation.

 

[itfitzme]

^If we're gonna discover life, I'd like it to be in our lifetime. I remember when we launched our first probe, with a gold record and a couple of still nudes. It is just reaching the edge of the heliopause. Space exploration is really slow. And at this rate, the expanding universe is going to have the nearest planetary system out of reach before we get there. Damn Star Wars saga was disappointing enough, with that last cartoon installment. Gene Rodenbury promised we'd go where no man had gone before. We aren't even to Mars yet, in person. The sun is going to supernova before we get past this solar system. The Egyptians build pyramids out of multiton stones with nothing but ropes and logs.

If the Federal Reserve would pair up with NASA and just litter Mars with hundredndollar bills, we would have this thing done in no time.