I know this is a joke, but it's weird that scientist know the Dinosaur were wiped out on a Tuesday.

I think there are misconception here.

Scientists are not "smart" in many people context. They can not learn or know things without experiments, discuss, research, studying. So, any assumptions and theories (like the earth have gravity, there are microbes around us) can not be made without strong proofs and evidences.

When the proofs and evidences are strong enough, scientists will call that assumptions as (mostly) fact. if it's not – just wait and find more evidences, do everything all over again.

And if the (mostly) fact is challenged by new strong evidences, that (mostly) fact dies. If the new evidences is not strong enough, that (mostly) fact survives.

And… there are so many type of "scientist". Biologist, chemist, physician, astronomer, for example. A scientist who studies in a branch of biology may or may not know a lot about astronomy. So, just don't get mixed up.