Astronomy: Part 2. Phases of the Moon The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The phases always.

Astronomy: Part 2

Phases of the Moon

The Moon passes through four major shapes during a cycle

that repeats itself every 29.5 days.  The phases always follow one another in the

same order:New moon

First quarterFull moon

Third quarterNew moon

Phases of the Moon

• The lighted side of the moon faces away from the Earth. 

• This means that the sun, Earth, and moon are almost in a straight line, with the moon in between the sun and the Earth. 

The right half of the Moon appears lighted and the left side of the Moon appears dark

The lighted side of the moon faces the Earth and the Sun

The Earth, Sun, and moon are almost in a straight line, with the Earth in the middle

Photo by Robin Afinowich

• Also called a last quarter moon.

• Only the left side of the moon appears lighted

• The next main phase will be a new moon again

There are other phases that fall between the ones we already looked at

Like… Waxing cresent Waxing gibbous Waning gibbous Waning cresent

Solar Eclipse Lunar Eclipse

The moon gets between the sun and the Earth

So the moon’s shadow is cast on the Earth

Occurs during a new moon

Occurs during a full moon

The Earth is between the Sun and the Moon

The Earth’s shadow is cast on the moon

The moon is ¼ the size of the Earth or 3475 km in diameter (the Earth is 12,756 km in dia.)

Gravity is only 1/6 that of Earth – a 150lb man would weigh only 25lbson the moon

Caused by impact from another moving body

The moon has many, the Earth only a few

The light colored part of the moon are highlands

These contains the moon’s mountain ranges

The dark colored parts are called mare or maria – smooth areas of the moon

These are long valleys or trenches found in the maria

Possibly caused by lava flows

The Giant-Impact Theory: A Mars sized body slammed into the early Earth

What was knocked out formed the moon