Phases of the Moon · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

The Moon's Changing Faces

Science · Space Systems & Earth's History · ages 11-12
Name ______________________   Date ____________

  1. Which sentence describes a lunar eclipse?

    • Earth moves between the Sun and the Moon
    • The Moon moves between the Sun and Earth
    • The Moon vanishes completely for a whole month

  2. What causes the Moon to look like a full circle some nights and a thin sliver on others?

    • Earth's shadow covering part of the Moon
    • The changing angle of sunlight hitting the Moon as seen from Earth
    • The Moon changing size as it moves through space

  3. The Moon's phases take about a full year to repeat.

    Circle one:   True   False

  4. Look at the Moon's cycle below. Which phase comes right after First Quarter, as the Moon keeps growing toward Full?

    New MoonWax Cres1st QtrWax GibFull MoonWan GibLast QtrWan Cres
    • Waxing Gibbous
    • Waning Crescent
    • New Moon

  5. If tonight is a new moon, about how many days will pass before the next new moon?

    Answer: ______________

  6. One afternoon, Maria watches the Moon slide in front of the Sun and block its light. What is happening?

    • A solar eclipse, because the Moon is between the Sun and Earth
    • A lunar eclipse, because Earth is between the Sun and the Moon
    • A new moon phase, with no eclipse at all

  7. Tonight is a Full Moon. The whole cycle of phases takes about 28 days. Using the cycle below, about which phase will the Moon be in 21 days?

    Full MoonWan GibLast QtrWan CresNew MoonWax Cres1st QtrWax Gib
    • Full Moon again, right where it started
    • New Moon, the darkest phase
    • First Quarter, about a week away from Full again

  8. Diego explains the phases like this: 'The Moon changes shape because Earth's shadow covers a different part of it every night.' What is wrong with his explanation?

    • Nothing, his explanation is correct
    • Phases come from the changing angle of sunlight and the Moon's position; Earth's shadow only causes eclipses, not everyday phases
    • The Moon actually changes size a little every night
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Answer key

For grown-ups. Fold this page away before handing over the rest.

The Moon's Changing Faces W1-mt_4V-vYhFUcm-s1

  1. Earth moves between the Sun and the Moon · In a lunar eclipse, Earth sits between the Sun and the Moon, so Earth's shadow falls on the Moon.
  2. The changing angle of sunlight hitting the Moon as seen from Earth · The Moon just reflects sunlight. As it orbits Earth, you see different amounts of its lit half, and that changing angle creates the phases.
  3. False · The cycle of phases takes about 28 days, roughly a month, not a year.
  4. Waxing Gibbous · After First Quarter, more of the lit half becomes visible each night, so the next phase is Waxing Gibbous.
  5. 28 · The full cycle from new moon back to new moon takes about 28 days.
  6. A solar eclipse, because the Moon is between the Sun and Earth · The Moon can only block the Sun from Earth's view during a solar eclipse, when it passes directly between them.
  7. First Quarter, about a week away from Full again · 21 days is three quarters of the 28-day cycle, which lands close to First Quarter, one week before the next Full Moon.
  8. Phases come from the changing angle of sunlight and the Moon's position; Earth's shadow only causes eclipses, not everyday phases · Earth's shadow does fall on the Moon, but only during a lunar eclipse. Everyday phases come from the changing sunlight angle as the Moon orbits.
Worksheet · LightMySky