MOON BASICS
Does the Moon make its own light?
No. It reflects light from the Sun.
Which phase occurs when we cannot see the illuminated side of the Moon from Earth?
New Moon
What does waxing mean?
The visible illuminated part of the Moon is increasing.
Which object provides the light that makes the Moon visible?
The Sun
True or false: The Moon physically changes shape during the month.
False
What does the Moon travel around?
Earth
Which phase occurs when the whole visible face of the Moon appears illuminated?
Full Moon
What does waning mean?
The visible illuminated part is decreasing.
During a new Moon, which object is approximately between the Sun and Earth?
The Moon
New Moon → Waxing Crescent → ______
First Quarter
About how long does one complete Moon-phase cycle take?
About 29.5 days
Which phase comes directly after waxing crescent?
First quarter
Is waxing gibbous before or after the full Moon?
Before
During a full Moon, Earth is approximately between which two objects?
The Sun and the Moon
A Moon is:
What phase is it?
Waning crescent
Why does the Moon appear to change shape even though the Moon itself does not actually change shape?
Because as the Moon orbits Earth, we see different amounts of its sunlit half.
The Moon is more than half illuminated and still becoming more illuminated. Name the phase.
Waxing gibbous
The Moon was full a few nights ago and now less of it appears illuminated. Is it waxing or waning?
Waning
Why can we see a full Moon when it is on the opposite side of Earth from the Sun?
The side of the Moon facing Earth is illuminated by sunlight.
A student sees a first-quarter Moon.
Approximately where are they in the 29.5-day lunar cycle?
A. Just beginning
B. About one-quarter through
C. Halfway through
D. Nearly finished
B — about one-quarter through
A student says:
“The dark part of the Moon is caused by Earth's shadow.”
Are they correct? Explain.
No. Normally the phases are caused by our changing view of the Moon's sunlit half as it orbits Earth. Earth's shadow causes a lunar eclipse, not ordinary Moon phases.
Put these phases into the correct order:
Full Moon – New Moon – Waxing Gibbous – First Quarter – Waxing Crescent
New Moon → Waxing Crescent → First Quarter → Waxing Gibbous → Full Moon
A Moon is more than half illuminated. How could you tell whether it is waxing gibbous or waning gibbous without just saying “it looks gibbous”?
You need to know whether the illuminated portion is increasing or decreasing / whether it is moving toward or away from the full Moon.
The Moon is always half illuminated by the Sun. So why don't we always see a half Moon from Earth?
Because the Moon changes position as it orbits Earth, so we see different portions of its illuminated half.
Imagine the Moon stopped orbiting Earth.
Would we continue to see the normal repeating 29.5-day sequence of Moon phases?
Explain your answer.
No. The regular cycle of phases depends on the Moon changing position relative to Earth and the Sun as it orbits Earth.