Portrayal of the exoplanet HD 189733b in Celestia.
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.
As a tangent to yesterday’s post (and also because discussing bleak prospects for Mars appears popular), there’s another point in James Lovelock’s Gaia: A New Look At Life on Earth that seems relevant for today. It’s just been announced that NASA will send another rover to Mars in 2020 to compliment the work of the current Curiosity rover in its search for life. While Curiosity has been generally examining the environment with its hi-tech equipment to see if it could ever have been fit for life, this new rover would focus on studying the planet’s geology.
When writing the book, it was Lovelock’s view that the development of life on a planet inevitably acts to terraform that planet to make it even more fit to harbour life – such as how on Earth life has regulated our atmosphere in the last 3 billion years to keep the temperature constant, despite the fact it ought to be lowering. If Mars has ever had life on it, then this life should have modified the planet to make it more habitable, thereby leading to more life. This doesn’t necessarily mean that Mars should still be habitable now if it ever sustained life – some catastrophe could have destroyed the atmosphere, for example – but signs of former life ought to be more obvious. Certainly, it would suggest with certainty that no life exists now. In this theory I think it’s still possible that life never developed past basic bacteria before being wiped out, but the chances of such a short lifespan can be considered unlikely. If this is true then our search for life on Mars is probably in vain.
That’s not to say I don’t think we should be sending rovers to Mars. Quite the contrary! There is still so much we can learn from our neighbours whilst developing our own technological capabilities. I just don’t think we should be getting our hopes up for any big announcements.