Eclipses Overview and Types
Overview
This lecture explains what eclipses are, distinguishes between solar and lunar eclipses, and discusses the conditions needed for each type to occur.
Introduction to Eclipses
- An eclipse is when one object blocks the view of another.
- The word "eclipse" is different from "ellipse" (unrelated terms).
Types of Eclipses
- Two main types: lunar eclipse and solar eclipse.
- Both involve the Sun, the Moon, and the Earth aligning.
Solar Eclipse
- A solar eclipse happens when the Moon moves between the Sun and the Earth, blocking our view of the Sun.
- The sequence is: Sun → Moon → Earth.
- Solar eclipses only occur during the new moon phase.
Lunar Eclipse
- A lunar eclipse occurs when the Earth is between the Sun and Moon, and the Earth blocks sunlight from reaching the Moon.
- The sequence is: Sun → Earth → Moon.
- Lunar eclipses only occur during the full moon phase.
Why Eclipses Don't Happen Every Month
- The Moon’s orbit is tilted compared to Earth's orbit, so the Sun, Moon, and Earth do not perfectly line up every month.
- Most of the time, the Moon is either above or below the necessary alignment for an eclipse to happen.
Frequency of Eclipses
- Lunar eclipses are more common than solar eclipses.
- Earth's shadow is larger than the Moon's, making it easier for the Moon to move into Earth's shadow than for Earth to move into the Moon's small shadow.
- Most people will see more lunar eclipses in their lifetime than solar eclipses.
Key Terms & Definitions
- Eclipse — the blocking of one object by another so that it is unseen.
- Solar Eclipse — the Moon blocks the Sun as seen from Earth.
- Lunar Eclipse — the Earth blocks sunlight from reaching the Moon.
- New Moon — moon phase when the Moon is between the Earth and Sun; required for solar eclipse.
- Full Moon — moon phase when the Moon is opposite the Sun relative to Earth; required for lunar eclipse.
Action Items / Next Steps
- Review the moon phase diagram to understand when eclipses can occur.
- Be able to identify the alignment for both types of eclipses.