Quote from the rules(p. 15):
17.4 Doomsday Machine Effects wrote:
... If, after combat, a DM is in a hex with an asteroid or planet (with or
without a colony), it will destroy it. Remove it and any colony from
play. DMs get no benefits from destroying planets or asteroids. Any
other terrain has no effect on DMs.
The last sentence states that DM is not effected by Black Holes.