For the first time ever we have discovered clouds of water around an astronomical body outside of our solar system. WISE 0855 is a brown dwarf about 7 light years from earth, so extremely close in cosmic terms, and was first discovered in 2014. Since then astronomers at UCSC have been trying to get a good, close look at the spectrum of the planet thereby gaining an understanding of its composition.
When you take light from a source and break it up into its component parts there will be certain gaps in the rainbow of colours. Those gaps are there because light of that frequency is being absorbed by whatever compounds happen to be present either in the source of the light or in what the light has subsequently passed through to reach your detector.
Many people assume that a brown dwarf is a star, but it isn’t; indeed, they are often referred to as ‘failed stars’. They have masses of 2-50 times that of jupiter and are too big to be planets but not big enough to sustain a fusion reaction and become a star. As they’re not fusing hydrogen atoms together they don’t produce much heat and are some of the coldest objects we are able to detect in the universe. In fact, WISE 0855 is the coldest thing we have ever observed outside of our solar system. WISE 0855 is a bracing -23 degrees Celsius compared to jupiter’s -143 degrees Celsius.
Using Hawaii’s Gemini North telescope at the top of Mauna Kea, the team were able to get good spectrum data from the planet and confirm that the planet’s atmosphere is laden with significant quantities of water vapour.
WISE 0855 is a rogue planet, one that doesn’t orbit a star, it just makes its own way through the galaxy; it’s also the closest known planet to us. Given its earth-like temperature and abundance of water it’s amazing to think that there could be life of some kind just bumbling through the universe minding its own business. It could be the case that these types of planets are quite common, but as they don’t give off visible light and very little infra red light they are devilishly difficult to discover; it’s quite remarkable that we found this example.
The more instances we find of reasonable candidates for life like this one the more we can hypothesise that life, at least in some kind of basic microbe-like form, could be really quite common out there. With so many billions of opportunities it seems perverse to think that we are alone. I think we need to really push our exploration of the moons of jupiter and saturn. Whilst we still only have an n of 1 the argument for life elsewhere in the universe will be hobbled. If we have n of 2, there’s every reason to think that n=∞