The only reason we have mountains is because the Earth is shrinking, causing its surface to buckle up into peaks. At least that’s what people believed 200 years ago. Nowadays we know that it’s all down to tectonic activity on Earth, but somewhere else in our Solar System, shrinking may actually be the reason for mountains. The planet: Mercury.
New images released by NASA following the flyby of Mercury by their Messenger probe in January have revealed strange new things about a planet that up until now was considered, well, boring.
So what caused Mercury to shrink, and then create these huge mountain chains? It’s all down to the fact that Mercury’s interior cooled after its formation; when things cool, they contract. Because Mercury has not had any tectonic activity (volcanoes, earthquakes) for billions of years, the effects of that contraction can still be seen today.
Also revealed in the new photos was a strange feature, dubbed ‘The Spider’ (see image on right). It is thought to be the remnants of an ancient volcano, though there is also a meteorite crater near the peak.
Another revelation was that Mercury’s not so bland and colorless after all – faint blue and red/pink tinges have been detected by Messenger’s cameras (see image at top).
Messenger makes another flyby in October this year, then again in 2009, before finally coming into orbit around the Solar System’s smallest planet in March 2011. I think we can expect plenty more fascinating news from Messenger over the next few years.