Overview
This lecture explains the concepts of solar and lunar eclipses, their causes, types, and important terminology related to these astronomical events.
Solar Eclipse
- A solar eclipse occurs when the Moon passes between the Sun and Earth, blocking sunlight from reaching Earth.
- Solar eclipses only happen during a new moon phase.
- There are three types of solar eclipses: total, partial, and annular.
- In a total solar eclipse, the Moon completely covers the Sun as viewed from Earth.
- In a partial solar eclipse, only part of the Sun is obscured by the Moon.
- In an annular eclipse, the Moon covers the center of the Sun, leaving a ring of sunlight visible.
Lunar Eclipse
- A lunar eclipse occurs when the Earth passes between the Sun and the Moon, causing Earth's shadow to fall on the Moon.
- Lunar eclipses only take place during a full moon.
- There are three types of lunar eclipses: total, partial, and penumbral.
- In a total lunar eclipse, the entire Moon moves into Earth's umbra (darkest shadow).
- In a partial lunar eclipse, only part of the Moon enters Earth's umbra.
- In a penumbral lunar eclipse, the Moon only passes through Earth's penumbra (lighter shadow), causing only a subtle shading.
Eclipse Terminology & Mechanics
- The umbra is the darkest part of the shadow where light is completely blocked.
- The penumbra is the lighter part of the shadow where light is only partially blocked.
- Eclipses do not happen every month because the Moon's orbit is tilted relative to Earth's orbit around the Sun.
Key Terms & Definitions
- Solar Eclipse — Moon blocks sunlight from reaching Earth.
- Lunar Eclipse — Earth blocks sunlight from reaching the Moon.
- Umbra — Darkest, central part of a shadow.
- Penumbra — Lighter, outer part of a shadow.
- Total Eclipse — One celestial body completely blocks another.
- Partial Eclipse — Only part of a celestial body is blocked.
- Annular Eclipse — Moon covers Sun's center, leaving a ring.
- Penumbral Eclipse — Only penumbra covers the Moon, causing faint shading.
Action Items / Next Steps
- Review diagrams of eclipse geometry.
- Make a comparative chart of solar and lunar eclipses.
- Complete assigned reading on eclipse safety and observation.