A rocket is an experiment; a star is an observation.
You can say the opposite of something you've said but you can't do the opposite of something you've done.
We say of an animal that it is intelligent, and we say the same thing of a woman; but in neither case is it usually appropriate, clearly for very different reasons.
When the English have scored a goal, they think nothing more remains to be done.
Try not to turn your life into a race, least of all an obstacle race.
Even if you're not going anywhere, don't get in the way.