SPACE

Why the Moon shows one face

A child compares the Moon’s familiar dark markings through a small telescope. Look closely — what might matter?

The Moon travels around Earth, yet the same patches keep looking at us. Is it frozen, or turning in a special rhythm?

Orbit and body spin are separate motions.

A moon can travel around a planet and turn around its own center at the same time.

Tap through one matched trip and watch the painted face stay inward.

Tap four orbit stops. The body turns one quarter at each stop, keeping its gold face toward Earth.

Change a generic moon’s spin-to-trip ratio and watch alignment markers.

slow spinfast spin

The locked moon starts again with orbit doubled and spin unchanged.

A new model begins locked. Then its trip becomes twice as fast while its spin rate stays the same.

The trip becomes twice as fast. The old spin rate stays unchanged.

The moon’s trip becomes TWICE as fast, but its spin rate stays unchanged. After one new fast trip, which side faces Earth?