How did the maria form?

By lava flooding ancient impact basins and solidifying

How do most large craters on the Moon form?

Impacts of meteoroids and asteroids

The Moon has almost no atmosphere, water or geological activity

Its rotation period equals its orbital period (synchronous rotation)

A slight apparent rocking of the Moon as seen from Earth

The Moon's synchronous rotation keeps it turned away

12questions. Pick an answer and you'll see why right away.

What is the approximate mean diameter of the Moon?
How do the maria appear to the naked eye?
How did the maria form?
How do most large craters on the Moon form?
Why are craters much better preserved on the Moon than on the Earth?
What are the Moon's rotation and orbital periods?
Why do we always see the same side of the Moon?
What is lunar libration?
Roughly what fraction of the Moon's surface can be seen from the Earth over time?
Which named feature is the Apollo 11 landing site?
Why does the far side of the Moon stay hidden from the Earth?
Roughly how many times wider is the Earth than the Moon?