Whilst the mainstream media would have you believe that the bright spots on Ceres were a surprise to everyone they’ve actually been something we’ve known about for quite some time. However in the past they seemed to come and go making consistent observations of them rather difficult. With the Dawn craft now in a stable orbit around Ceres we are now in the position to observe them much more closely, bringing us ever closer to understanding what the heck it is. There’s still a lot more for us to understand but the first round of preliminary observations have provided some very good insight into the bright spot’s composition and its likely origin.
The first revelation to come out of Dawn’s observations was that the bright spot was in fact not a singular entity and is made up of several spots. There’s 2 large primary bright spots that are accompanied by a bunch of smaller ones which indicates that, as we make better observations, that those larger spots are most likely made up of multiple smaller spots as well. As the above ground map indicates there are actually a bunch of other bright spots dotted over Ceres’ landscape however none of them were close enough together to be observable before Dawn began making closer approaches. The origins of these spots remain something of a mystery however there are several prevailing theories about how they could have been created.
Ceres has been observed as having a very tenuous atmosphere which could only have arisen from outgassing or sublimation from its core. In early 2014 observations of Ceres detected some localized cryovolcanoes which are dumping some 3KG of water out into space every second supporting the theory that there’s some form of water hidden within Ceres. This supports the theory that these bright spots are most likely water ice (which would have the required reflectivity) but at the same time water in a vacuum tends to sublimate very quickly which begs the question of how long these bright spots have been around and how long they’ll last.
It’s quite possible that the ice in the crater was revealed by a recent impact and thus we’re just lucky that the bright spot is there for us to observe it. Considering that Ceres sits within the asteroid belt between Mars and Jupiter this is a very real possibility although that does then raise the question of why we’re not seeing more bright spots than we currently are. This is what then fuels other, more exotic, theories about what’s at the base of that crater such as a large metallic deposit. However evidence to support those theories isn’t yet forthcoming however once Dawn starts making closer approaches there is potential for some to come to light.
Needless to say the next few months of observations will prove extremely valuable in determining the bright spots’ elusive nature. Whilst the reality is likely to be far more dull and boring than any of the exotic theories make it out to be it’s still an exciting prospect, one that will give us insight into how solar systems like ours form.