It is for the 1st time that astronomers determined a planet’s true color, the one orbiting one other star.This world, known to be HD189733b, appears to have deeper azure hue, most likely result of the glass or silicate rain in atmosphere that scatters the blue light.
The details of this discovery, which is made with Hubble Space Telescope, would appear in the Astrophysical Journal Letters.Though, it could be said to resemble the Earth from distance, HD189733b happens to be big gas giant that orbits near the host star.
Temperature of this planet’s atmosphere tends to be scorching 1000oC, and it does rain glass, sideways, with the howling 7000km/hr winds.The atmosphere it has is exotic and dramatically changeable, with hazes as well as violent evaporation bursts.
At distance of sixty-three light years, this alien world happens to be one among the nearest of exoplanets to the Earth which could be seen to be crossing face of the star it’s orbiting.It is extensively been studied by the space- and ground-based telescopes. The astronomers now have measured the visible color it acquires.
University of Exeter’s Prof. Frederic Pont said that measuring the colour is the real first – one could actually imagine that what the planet will look like once he could look directly at it.
To measure that what the planet will appear to be in front of our eyes, astronomers did measure the amount of light that was reflected right from the surface, property called albedo.
HD 189733b tends to be faint and it is quite near to the sun. Though, when this planet passed from the back of the host star, astronomers could measure the changes in spectrum while light that was reflected by planet was blocked out temporarily.
1st author of this paper, Oxford University’s Tom Evans explained, “We saw the brightness of the whole system drop in the blue part of the spectrum when the planet passed behind its star.
“From this, we can gather that the planet is blue, because the signal remained constant at the other colours we measured.”
The Earth appears to be blue when seen from space because oceans absorb the green and red wavelengths much strongly than the blue ones as well as reflect sky’s bluish hue.
The azure colour of the exoplanet doesn’t come from reflection of any ocean, according to researchers, but it’s probably because of the turbulent and hazy atmosphere that’s being laced with the silicate particles, the ones responsible to scatter the blue light.Favorable case was presented by HD189733b for such type of measurements because it does belong to class of the planets known to be hot Jupiters. Such massive planets tend to be same in size as gas giants of Solar System, though, instead they lie quite close to the parent stars.