Lunar and Solar Eclipses – Lesson Summary

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Learning Objective

In this lesson we will learn how lunar and solar eclipses result from specific alignments of the Moon, Earth and Sun.

Learning Outcomes

By the end of this lesson you will be able to:

  • Explain how the Moon’s orbital plane affects the alignment of the Moon, Earth and Sun.
  • Describe the alignment of the Moon, Earth and Sun during a Full Moon and a New Moon.
  • Describe how shadows consist of an umbra, penumbra and antumbra.
  • Explain how lunar eclipses and solar eclipses result from specific alignments of the Moon, Earth and Sun.
  • Describe the three types of lunar eclipses and the three types of solar eclipses.
  • Compare lunar eclipses and solar eclipses.

 
lunar and solar eclipses lesson contents

(Image: paul, Adobe Stock)

Lesson Topics

1 | The Moon’s Orbital Plane

2 | The Positions of the Moon, Earth and Sun During a Full Moon

3 | The Positions of the Moon, Earth and Sun During a New Moon

4 | Shadows – Umbra, Penumbra and Antumbra

5 | Lunar Eclipses

6 | Solar Eclipses

7 | Comparing Lunar and Solar Eclipses

8 | Summary

Lesson Summary

  • The Moon’s orbital plane is titled by approximately 5° relative to Earth’s orbital plane.
  • This means that there are only two points during the Moon’s orbit around Earth where the Moon is in line with Earth’s orbital plane, but these vary for each lunar cycle.
  • If the Moon crosses Earth’s orbital plane during a Full Moon, a lunar eclipse occurs as a result of direct alignment of the Moon, Earth and Sun.
  • During a lunar eclipse, Earth is directly between the Moon and the Sun, casting a shadow over the Moon.
  • If the Moon crosses Earth’s orbital plane during a New Moon, a solar eclipse occurs as a result of direct alignment of the Earth, Moon and Sun.
  • During a solar eclipse, the Moon is directly between Earth and the Sun, casting a shadow over Earth.
  • Shadows cast by objects in front of the Sun consist of three parts:
  • The umbra is the inner region of a shadow, from which no part of the Sun is visible.
  • The penumbra is the outer region of a shadow, from which some of the Sun is visible.
  • The antumbra is a region that extends from the tip of the umbra, from which the outer part of the Sun is visible.
  • There are three types of lunar eclipses:
  • A total lunar eclipse occurs when all of the Moon is within Earth’s umbra.
  • A partial lunar eclipse occurs when part of the Moon is within Earth’s umbra.
  • A penumbral lunar eclipse occurs when the Moon is within Earth’s penumbra.
  • There are three types of solar eclipses:
  • A total solar eclipse occurs when the Sun is fully covered by the Moon.
  • It is viewable from within the Moon’s umbra.
  • A partial solar eclipse occurs when the Sun is partially covered by the Moon as a result of imperfect overlap.
  • It is viewable from within the Moon’s penumbra.
  • An annular solar eclipse occurs when the Sun is partially covered by the Moon as a result of the Moon being too distant to fully cover the Sun.
  • It is viewable from within the Moon’s antumbra.
  • Differences between lunar and solar eclipses include:
  • A totally eclipsed Moon is still visible from Earth, but a totally eclipsed Sun is not visible.
  • A lunar eclipse can be viewed from anywhere on Earth that has a view of the Moon, but a solar eclipse can only be viewed from a small region on Earth.
  • For any given location on Earth, a lunar eclipse is much more likely to occur.
  • Lunar eclipses last longer than solar eclipses.

 
solar eclipse graphic

(Image: NASA)

(Header image: davidhoffmann.com, Adobe Stock)