Moon Basics
What is the source of light that makes the Moon visible from Earth?
The Sun
What happens to the side of the Moon that faces the Sun?
It is lit by sunlight.
When the lit portion of the Moon appears to get larger each night, what is this called?
Waxing
What object does the Moon orbit?
Earth
Why doesn’t the Moon look the same every night?
Because its position changes as it orbits Earth.
Does the Moon produce its own light or reflect light?
It reflects sunlight
Does Earth’s shadow usually cause the dark part of the Moon?
No. It is the side not facing the Sun.
When the lit portion gets smaller each night, what is this called?
Waning
About how long does it take the Moon to orbit Earth?
About 1 month (27–29 days)
What does the “terminator” on the Moon refer to?
The border between the light and dark sides.
How much of the Moon is always lit by the Sun?
Half of the Moon
When does Earth’s shadow actually fall on the Moon?
During a lunar eclipse
What phase occurs when the Moon appears fully lit from Earth?
Full Moon
If the Sun is shining on the left side of the Moon, which half will be bright?
The left half facing the Sun
Why is the Moon not completely bright even though sunlight hits it?
Only half of the Moon faces the Sun at any time.
Why do we only see part of the lit half of the Moon from Earth?
Because the Moon moves around Earth and we see different portions of the sunlit half.
Why does half the Moon always appear dark in space?
Because the Sun can only illuminate one half at a time.
What phase occurs when the Moon appears completely dark from Earth?
New Moon
Why might the light portion of the Moon appear larger several days later?
Because the Moon moved in its orbit so we can see more of the sunlit side.
If the Moon moves so we see less of its lit side, what happens to the visible-light portion?
It gets smaller.
What is the name for the changing appearance of the Moon as seen from Earth?
Moon phases
True or False: The Moon becomes dark because clouds block sunlight.
False
Why does the Moon sometimes appear to grow brighter and sometimes dimmer?
Because the Moon orbits Earth, we see different parts of the sunlit half.
Can the half of the Moon facing Earth ever be completely dark?
Yes, during a New Moon when the lit half faces away from Earth.
Explain why the Moon looks different from Earth even though the Sun always lights half of it.
Because the Moon moves around Earth, changing the angle we see of the sunlit half.