For the first time ever, astronomers have managed to discern the colour of a planet outside of our solar system. The exoplanet, HD 189733b,* is thought to be blue in colour. They achieved this remarkable discovery by measuring light from the planet when exposed then measuring again when it slipped behind the star. They noticed a substantial drop of wavelengths corresponding to the colour blue when this happened. Unfortunately for the possibilities of finding life, this is unlikely to be water. The planet is thought to be a gas giant which practically hugs its star, giving it a temperature of around 1,000C. The blue colour probably comes from silicate precipitating in the atmosphere, which reflects light from the star. That’s right – the planet contains glass rain. Molten silicate rains horizontally in a sideways direction at around 7,000 km/h. Just imagine the geographical processes of that planet! The geology, the chemistry, the…
Every now and then a phrase or an idea leaps out from an astronomical discovery which excites the imagination; ‘glass rain’ is one of those. I don’t suppose molten silicate is even a particularly unusual occurrence, but it does indicate just how vast and diverse the Universe must be. This planet is only 63 light years away and scarcely observable as it is – what wonders could exist beyond our reach? If scientists expand on this technology and method, the possibilities of future discoveries are breathtaking. It’s moments like these I wish I had become an astrophysicist.
*And scientists wonder why exoplanets never enter the public imagination.