The opening of the sequel,2010, states that the second monolith was discovered under the Sea of Tranquility. However, this does not jive with the original film and novel which finds the monolith near (and named for) this prominent lunar carter which is nowhere near the Sea of Tranquillity. Identify this crater, one of the largest and easily seen on the moon, named for a Danish scientist, that is located near the moon's south pole.
Tycho (Brahe)