Tuesday, 27 November 2012

(Pac)Man on the moon



Ok, so it's not our moon... and there's been two 'men' found, on separate moons. This is still a really interesting finding, though. It would seem that the rotation and orbit of two of Saturn's moons, coupled with the impact of high energy electrons on their surfaces, have contrived to produce a striking image of 80's arcade game character 'Pacman' on both Mimas and Tethys when thermally imaged during the day.

So, how is this all happening? Well, it’s all rather complicated but to break it down; it appears that high energy electrons found within either moon’s ‘magnetosphere’ are flowing retrograde to the spin of each celestial body. It’s thought that this is causing to impact the surface of the moons leading hemisphere and somehow increase thermal inertia at lower latitudes. An increase in thermal inertia simply means that the lower latitudes of Mimas and Tethys are less prone to change in temperature in either direction. So how does this lead to the moons looking like Pacman under  thermal imaging?
Look specifically at the image at the top right hand corner of the figure above (taken from Howett et al, 2012). You can clearly see that the temperature near the equator of Tethys is cooler than that further away and that this difference disappears the further away you look from the leading hemisphere… creating what can only be described as Pacman.

I fully expect a report claiming the existence of multi-coloured ghosts on Mimas and Tethys to be published within the next couple of years!