Astronomers have, for the first time, managed to determine the exact hue of a distant exoplanet; a gas giant some 63 lightyears away.
HD 189733b is a deep blue colored gas giant 63 lightyears from earth. The previous statement is one that humans have never been able to make before now. That’s because HD 189733b is the very first planet ever to have its true color determined by astronomers. The planet, which is a so called Hot Jupiter (a gas giant orbiting very close to its star) makes a complete orbit around its sun every 2.2 Earth days, and has been studied before by several science teams, but never to find out what it actually looks like: “[...] measuring its color is a real first. We can actually imagine what this planet would look like if we were able to look at it directly,” says Frédéric Pont, leader of the Hubble Observing Program.
The team managed to determine the color by measuring color changes reflected from the solar system as the planet passed behind its sun: “We saw the brightness of the whole system drop in the blue part of the spectrum when the planet passed behind its star,” said Tom Evans of Oxford University, “From this, we can gather that the planet is blue, because the signal remained constant at the other colors we measured.”
Artists’ illustration of the planet, for once kind of accurate.
From afar, the planet probably has a similar color to our home-world, but up close, things are less ideal. NASA’s Spitzer space telescope helped map the weather on the planet while producing one of the first temperature maps of an exoplanet back in 2007. While temperatures average around 1000 degrees Celsius, the temperature difference between day and night on the blue planet is around 260 C, leading to strong winds of up to 7,000 km/h.