I found an arsenic rich moon while I was out exploring and I was finding a large number of outcrops along a mountain ridge and I kept driving and collecting. But what I was driving on turned out not to be a mountain range at all. It was the ridge of the biggest crater I personally have ever come across in the game.
If you look closely you can see my SRV towards the bottom left for a sense of scale
@Lightspeed Yeah, it was bit of a stroke of luck I noticed it in time. I was just cruising around searching for minerals, happened to look to the sky and realized the sister planet is moving directly towards the main star. The eclipse itself lasted about an hour. It was pretty cool sight to behold.