Earth and the Moon (Phases of the Moon)

 

The moon – Earth’s natural satellite

Phases of the Moon

The Moon looks different over time when we see it from Earth. Sometimes, the Moon is hard to see in the sky and at other times it can look like a thin curve, a full circle – or something in between.

A Moon phase is the shape of the part of the Moon that we can see, and this changes slowly over a lunar month.

 

What is a lunar month?

A new Moon begins a lunar month, which lasts about 29.5 days. The new Moon is hard to see in the sky because the Sun’s light hits the side of the Moon that faces away from Earth.

As the Moon orbits around Earth, the lit part of the Moon’s surface starts to face towards Earth, and we see a thin crescent Moon.
The Moon has these phases during a lunar month:

 

The eight phases of the moon

 

 

Section 2: Knowledge Check

🌍 Knowledge Check: Earth and Moon

Test your knowledge on the rotation, orbits, and characteristics of the Earth and the Moon.

1. How long does it take for the Earth to complete one full rotation on its axis?

• 28 days
• 24 hours
• 365.25 days

2. Why do we have years (365.25 days)?

• Because that is how long the Moon orbits the Earth.
• Because the Earth rotates 365 times a day.
• Because that is how long the Earth takes to orbit the Sun.

3. Where does the light we see from the Moon come from?

• The Moon is a star and produces its own light.
• The Moon reflects light from the Sun.
• The Moon reflects light from the Earth.

4. How long is the orbital period of the Moon around the Earth?

• Approximately 28 days
• Exactly 24 hours
• 12 hours

5. Which of the following is true about Earth's movement?

• The Sun orbits the Earth once a year.
• The Earth is stationary while the Moon and Sun move.
• The Earth orbits the Sun while rotating on its axis.

Click to Reveal Answers

1. 24 hours (This causes our day and night cycle).
2. Because that is how long the Earth takes to orbit the Sun (One full orbit equals one year).
3. The Moon reflects light from the Sun (The Moon is non-luminous).
4. Approximately 28 days (This is roughly the length of a calendar month).
5. The Earth orbits the Sun while rotating on its axis (Earth has both orbital and rotational motion).

 

Summary:

 

• Orbiting many of the planets are natural satellites, called moons.
• Our Earth has one moon.
• It moves in an orbit round the Earth.
• It is held in this orbit by the pull of Earth's Gravity.
• It goes around the Earth in an anti-clockwise direction.
• The Earth also spins in an anti-clockwise direction at the same time from west to east.
• It takes one lunar month (28 days) to complete one orbit of the Earth.
• It has no light of its own.
• As it goes around the Earth, we see the moon surface reflecting the Sun's light.
• It looks different at different times of the month, changes its shape.
• It has phases.  The phases are about 4 days apart.