The moons   More Triton   Proteus   Halimede

The planet Neptune was first discovered in 1846 and just several weeks later an English astronomer called Willian Lassell spotted Triton, a moon with a very peculiar orbit indeed! All the major moons in our solar system rotate in the same direction as the planet that they belong to, but Triton alone goes in the opposite direction, which has led to speculation that Triton was not formed at the same time as Neptune but developed elsewhere and was trapped by Neptune's gravity. Neptune itself was named after the Greek sea god Poseidon (Neptune is the Roman name for Poseidon) and Triton was one of the sons of Poseidon so it was an apt name for the moon.

Another strange thing about Triton is that it rotates around its own axis in exactly the same time as it rotates around Neptune, and this means that the same face points towards Neptune all the time.

Hardly surprisingly very little was known about a moon which is such a huge distance away from Earth until Voyager 2 flew within 25,000 miles on it in 1989, and it was found to measure roughly the same size as our Earth Moon but it appears to be composed mainly of water ice covering a rocky core with the surface covered by solid nitrogen and methane; it is pretty darned cold on Triton! There is still a thin atmosphere, despite this, of mainly gaseous nitrogen and dark streaks on the surface indicate the presence of winds, although just how these are formed remains a mystery at present.

So how did this mysterious object get there in the first place? The currently accepted theory is that it came from the outer solar system and, travelling a little too close to Neptune, was slowed down by drag from Neptune's atmosphere, or, possibly, by a collision with a smaller moon. This could have placed it in to a highly elongated orbit around the planet, with the gravitational effects of both of them gradually dragging it into a circular orbit over a very long period of time. This must have been a very traumatic period for both the planet and the moon as the gravitational forces would have been likely to have generated immense heat. This could have been the reason why Triton appears to have a very dense core and lighter materials around the outside since this would have occurred naturally had it been a molten body.

Out of this world -  my Mercedes 

Copyright 2009