HD 189733b is a Jupiter-sized gaseous planet orbiting a yellow dwarf in the constellation of Vulpecula. With a good pair of binoculars ya can see this star just a hair’s breadth to the east of the Dumbbell Nebula.
With something a little more sophisticated, ya can see the star darkening as this planet passes in front of it, once every coupla days.
And with the best piece of glass on the planet, yer can see even more. Frederic “Ball” Pont from Geneva University and a few pals commandeered the Hubble Space Tleescope to take a look at HD 189733b with the aim of trying to work out what it’s atmosphere is made of. The idea is that, as it grazes its sun, the atmosphere should absorb all kindsa frequencies that Hubble ought to be able to pick up.
But don’t getcha hopes up. Turns out, the atmospheric spectrum is featureless. That means it’s full o’ haze: submicron bits of dust. The atmospheres of Titan, Triton and Venus in our Solar System demonstrate a similar lack of features at these frequencies. Ball Pont and pals speculate that it might be stuffed full of the condesates of iron, silicates and aluminin oxide. They make no mention of the possibility of organic gunk.
But they do say one thing with certainty: when this yellow sun sets on HD 189733b, it looks red, just like ours.
Ref: arxiv.org/abs/0712.1374: Detection of atmospheric haze on an extrasolar planet: The 0.55 – 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope