Moon of the Month

So I haven't written for this blog in a while. I know- I'm an awful blogger and I'm very sorry. My record is truly poor considering that I have only just started this whole internet venture and I am now thoroughly ashamed of myself. To make up for this I thought I'd try and start a monthly feature on the many moons of our solar system because, to be honest, these little failed planets are often even more fascinating than their much larger spouses.

To begin then, I thought I'd kick things off with a doozy; Jupiter's moon Europa, first discovered by Galileo in 1610 and the smallest of the four Galilean moons, with an equatorial radius of 1,569km. Europa is undeniably a looker as moons go, shining with bizarre pink and blue hues and covered in enormous, artistic cracks in its outer icy layer. As it turns out it is also the smoothest object in the solar system, with an almost completely level surface and very few large craters. A useful fact for future pub quizzes if nothing else.

It's what lies beneath the harsh, icy crust of this moon however that is getting a lot of scientists, in particular astrobiologists who must normally spend a lot of time playing tetris and feeling depressed, rather excited. This is because it is believed that Europa harbours a gigantic moon-wide ocean of salt water, which may well also be rich in oxygen. Sound familiar? We all know that life can survive in our seas in temperatures well below freezing: Just take a look at the whales, seals, sea spiders and other amazing fauna that spend their whole lives in the Arctic Ocean despite winter temperatures of -30 degrees celsius. We also know from recent probing into the deepest depths of our oceans, that life can evolve in intense pressures and without sunlight  if thermal vents are present to provide vital warmth and nutrients. So surely it doesn't seem that far fetched to suppose that, just possibly, there may well be life (even if it is of the single-celled, slimy, microbial kind) lurking in the inhospitable cold of Europa's oceans?

Thermal vents are certainly likely to exist on the moon because of its eccentric orbit around its gargantuan gas giant. Europa experiences such strong tidal forces as it moves between perigee and apogee (its closest and furthest distances from Jupiter) that its surface has cracked and broken up, producing the crevices that run across the surface. All that squeezing also causes an intense amount of friction inside the moon and with that a whole lot of heat; it seems entirely likely therefore that hydrothermal vents may populate Europa's ocean floor pumping out water heated from deep within the moon by Jupiter's stranglehold. If that is the case, then life is in it's vast ocean is all the more likely.

It's particularly easy to see Europa at the moment as Jupiter is still putting on a show at almost its closest distance to the Earth for 60 years. Even small scopes should be able to pick out the bright dots of the galilean moons with ease, so you really don't have an excuse not to have a good look if you can. In March of this year NASA and the ESA announced their plans to launch a mission to Europa in 2020. They hope, not exactly to find life, but to evaluate the conditions for it and to improve our knowledge of Europa's icy crust and underlying ocean (of which we really know nothing at all). Who knows, they may well find little alien microbes blobbing around Europa within our lifetimes. Maybe I'll even be lucky enough to be working on the project? I look forward to the phone call...