This is a really nice piece. The concept of a huge asteroid or anything like that smashing into a planet overwhelms and frightens me, but at the same time it's so cool and awesome, lol.
Your gallery is amazing, but I think there's something missing from nearly all of your work, and that's a sense of atmosphere. Your landscapes are great and so well done, but there's not a whole lot of feeling in them.
For example, this one is a frightening event, so maybe putting in more of the reds and oranges to exaggerate that feeling; right now it's "WHOA, a huge ROCK is going to destroy most if not all of this planet!! Crazy!" but I think if you had more color in it the reaction would be more powerful.
Anyway, great work! Your gallery isn't getting as much attention as it ought to.