Meet HD 189733b, The Blue Planet Where It Rains Hot Glass

Eerily reminiscent of Earth, this artist illustration depicts the azure-hued planet HD 189733b, located 63 light years away. Hazy, prone to violent explosions of vapor and deathly hot, the planet is anything but earth-like. Credit: NASA, ESA, M. Kornmesser

Astronomers using the Hubble Space Telescope have surmised the color of another planet beyond our solar system. HD 189733b’s azure blue globe resembles Earth from afar but don’t be fooled. This is a frightening place.

Photo showing the star HD 189733, home to the blue planet discovered in 2005. The bright patch to the right is the Dumbbell Nebula also known as M27 in the constellation Vulpecula. Credit: NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

The scorching hot, Jupiter-sized world orbits a faint star 63 light years from the sun in the summer constellation Vulpecula; it’s one of the nearest exoplanets observed to transit or cross the face of its host star. If you could somehow survive a descent through its 1,800 F (1000 C) atmosphere, you’d better batten down the hatches. Howling winds of 4,350 mph (7000 km/hr) fling fine particles of searing glass sideways through the fiery air.

This plot compares the color of solar system planets to the color of the hot Jupiter-like HD 189733b. With the exception of Mars, the colors are primarily determined by the chemistry of the planets’ atmospheres.  HD 189733b’s deep blue color is produced by silicate droplets, which scatter blue light. Credit: NASA, ESA, and A. Feild (STScI/AURA)

This planet makes Hades feel like a pleasant summer afternoon. Blame its hot temperament on a tight orbit – only 2.8 million miles separate HD 189733 b from its host star. Our local hothead Mercury orbits almost 13 times farther from the sun. Day- and night-side temperatures differ by about 500 degrees F (260 C) at HD 89733b, causing fierce winds to roar across the planet.

This illustration shows the position of the sun, Alpha Centauri and the winter star Sirius from HD 189733b. Since the star-planet system is only 63 light years away, we share many of the same stars in our skies though the constellation figures would be altered. Credit: NASA, ESA, and G. Bacon (AURA/STScI)

Astronomers measured the light of the planet-star system before, during and after the planet passed in front of the star as it orbited. Once the planet disappeared behind the star, not only did the light of the whole system drop slightly, but the overall color balance changed. Instruments on Hubble recorded a decrease in the amount of blue light.

You can guess where the blue went – out of view with the planet. Earth’s blue hue comes from the atmosphere and oceans, but HD 189733b draws its color from a hazy, turbulent atmosphere rich with silicate (rock, glass) particles which scatter blue light.

Click HERE to read the full paper on this colorful discovery. Future exo-meteorologists may find this website on exo-climates illuminating.

18 Responses

  1. Giorgio Rizzarelli

    .. or should I say, the deep blue dot.
    Thanx also for the ExoClimes link, very interesting

  2. Marcelo Silva

    How is this possible? Hubble can not see Pluto details ! ( It’s a small planet, but too many close from Earth)

    1. astrobob

      Hubble can only see its color. Not even a shape. The “photo” is an artist illustration.

      1. caralex

        It seems a lot of these exoplanets are extremely close to their suns. I wonder if our solar system is an exception here, with Mercury so ‘far’ away from the sun in comparison?

        1. astrobob

          Hi Carol,
          Possibly, but more likely it’s a selection effect. We’re better at detecting large planets close to their host stars because they’re easier to measure with both the transit method and by changes in radial velocity (wobble). As detection methods become more refined more Earth-like planets farther from their suns should show up. The fact that we’re already nabbing some of them is hopeful.

          1. Aloha Astro Bob and All!

            One thing we have to remember is just how very, VERY far away these “planets” are. It takes extremely powerful, yet oh-so delicate, instruments to not only “find” these but once they do, they can measure and do many other functions using a variety of “filters” and things. Anyone ever notice how well our unmanned space program is going? Seems the only “bad” thing we hear about any equipment malfunctions is when some “space junk” hits a working satellite and disables it and that happens by “chance” really. They are to be commended (NASA).

            They can give artists enough information so they can come up with a reasonable and fairly accurate picture of what something “out there” would look like to our eyes and these artists have incredible talent! I’ve always been in awe of people who can sit down to a blank canvas and create works of “impossible”, at least to me, creations. How do they do it?!? Amazing…

            Just wanted to remind everyone that these places are NOT close-by. That’s all.

            Aloha For Now! ;-}

  3. randy

    I’ve always loved the artist’s renditions that accompany astronomy stories. What I really want though, is a website that accumulates all of them in one place. Anyone know if something like that exists?

    1. astrobob

      It rains glass – silicate particles – because the astronomers involved know the approximate temperature of this planet (extremely hot because it orbits its host star very close) and have detected the signature of silicates in its atmosphere using spectroscopy. That’s what colors it blue. The sideways reference refers to high winds caused by the extreme difference between dayside and nightside temperatures, which drives strong winds.

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