Phases and Eclipses of the Moon

Moon and Eclipses

• The main source of light for the moon is the sun.
• The different shapes of the moon are called phases, caused by the moon's rotation on its axis and its orbit around Earth.

Moon's Motions and Phases

• The moon has two main motions: rotation on its axis and orbit around Earth.
• The moon's rotation on its axis determines the side of the moon that always faces Earth, known as the near side.
• The main cause of the moon's phases is the changing angle of sunlight that reaches the moon as it orbits Earth.

Lunar Eclipses

• During a lunar eclipse, Earth blocks sunlight from reaching the moon.
• A total lunar eclipse occurs when the moon passes through Earth's umbra, the darker inner shadow.
• The penumbra is the lighter outer shadow that surrounds the umbra during a lunar eclipse.

Solar Eclipses

• A solar eclipse occurs when the moon passes between Earth and the sun, blocking sunlight.
• A total solar eclipse is a rare event in which the moon's shadow has a narrow path on Earth, causing total darkness.

Moon's Rotation and Phases

• The moon rotates on its axis once every 27.3 days, which is the same amount of time it takes to orbit Earth.
• The phase of the moon that we see from Earth is determined by the amount of sunlight that reflects off the moon's surface.

Eclipses and Moon's Surface

• The pattern of light-colored and dark-colored areas on the moon's surface is called terra and maria, respectively.
• The moon is bright enough to read by when it is full and is on the opposite side of Earth from the sun.

Eclipse Types

• A partial lunar eclipse occurs when the moon passes through Earth's penumbra, causing a partial shadow on the moon's surface.
• The moon always shows the same side to Earth due to tidal locking, a result of the gravitational interaction between Earth and the moon.