[Karibu]

Originally posted by Grandpa Kim:
If the troops win, you have gained one intact, populated, facility laden planet. If the troops lose, alas, your fleet will glass the planet.

Exceptions: If the planet has a low population, say 10m or less, you may glass it anyway when the overage of the Last shot slops over to the population. Warning: Using missiles is dangerous and may glass much bigger planets.
If the planet has sufficient defenses, your attack ships may lose. The troop transport will then try to capture the still defended planet. Obviously this rarely succeeds.

One exception more: If planet has enough defensive troops, the ground battle may Last several turns. In this case your fleet simply blockades the planet until the fight is over. Once my troops fought three turns over one planet until they won.