The amazing SPACE

In our entire solar system, the only object that shines with its own light is the Sun. That light always beams onto Earth and Moon from the direction of the Sun, illuminating half of our planet in its orbit and reflecting off the surface of the Moon to create moonlight. Sometimes the entire face of the Moon glows brightly. Other times we see only a thin crescent of light. Sometimes the Moon seems to disappear. These shifts are called moon phases.

The eight lunar phases are, in order: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent. The cycle repeats once a month (every 29.5 days).

 Like Earth, the Moon has a day side and a night side, which change as the Moon rotates. The Sun always illuminates half of the Moon while the other half remains dark, but how much we are able to see of that illuminated half changes as the Moon travels through its orbit.

(Source: https://science.nasa.gov/moon/moon-phases/)

The far side of the Moon can never be seen from Earth:

The Moon whirls around Earth with one side always facing our planet ― and it’s not as unusual as you would think.

Earth’s Moon rotates, but it takes precisely as long for the Moon to spin on its axis as it does to complete its monthly orbit around Earth. As a result, the Moon never turns its back to us, like a dancer circling ― but always facing ― its partner.

This phenomenon, called “synchronous tidal locking,” sounds like a weird coincidence ― but it’s actually quite common. All the solar system’s large moons are tidally locked with their planets. The bigger moons synchronize early in their existence, within hundreds of thousands of orbits. Some binary stars are tidally locked to one another, and evidence is building that many planets beyond our solar system are tidally locked with their stars.