The Moon’s rotation takes 27.3 days—the same amount of time it takes to revolve once around Earth. Because these two motions take the same amount of time,
the same side of the Moon always faces Earth.
The surface of the Moon reflects the light of the Sun.
Moon phases are the different ways the Moon appears from Earth. The phase of the Moon depends on the relative positions of the Moon, Earth, and the Sun

A new moon occurs when the Moon is between Earth and the Sun. During a new moon, the lighted half of the Moon is facing the Sun and the dark side of the Moon faces Earth.

Waxing means that more of the lighted half of the Moon can be seen each night
When more than one quarter of the Moon’s surface is visible, it is called waxing gibbous.

A full moon occurs when all of the Moon’s surface that faces Earth reflects light.

After the full moon, the phases are said to be waning.

Waning means that you can see less and less of the lighted half of the Moon each night.

It takes about 29.5 days for the Moon to complete its cycle of phases.

Recall that it takes about 27.3 days for the Moon to revolve around Earth. The difference in the numbers is due to Earth’s revolution. It takes about two extra days for the Sun, Earth, and the Moon to return to their same relative positions.

Eclipses take place when Earth blocks light from reaching the Moon, or when the Moon blocks light from reaching a part of Earth.

Sometimes, during a new moon, the Moon’s shadow falls on Earth. This causes a solar eclipse.

During a full moon, Earth may cast a shadow on the Moon. This
causes a lunar eclipse.
An eclipse can take place only when the Sun, the Moon, and Earth are lined up perfectly.

A solar eclipse occurs when the Moon moves directly between the Sun and Earth and casts its shadow over part of Earth.

The darkest portion of the Moon’s shadow on Earth is called the umbra

Surrounding the umbra is a lighter shadow on Earth’s surface. This lighter shadow is called the penumbra

When Earth moves directly between the Sun and the Moon and its shadow falls on the Moon, a lunar eclipse occurs.

Lunar eclipses happen only during the full moon phase.

A total lunar eclipse can be seen by anyone on the nighttime side of Earth

Dark, flat regions formed as the lava spread. These regions are called maria

The impact theory, states that the Moon formed billions of years ago from condensing gas and debris thrown off when Earth collided with a Mars-sized object.

When Galileo first used his telescope to look at the Moon, he saw that it was not
smooth but had craters and maria.