Types of Solar Eclipses

Overview

This lecture explains the different types of solar eclipses, how their visibility depends on your location relative to the Moon's shadow, and defines key terms associated with eclipses.

Parts of a Solar Eclipse

The Moon casts a shadow on the Earth with two main parts: the central dark Umbra and the lighter Penumbra.
Only people within the Moon's shadow see a solar eclipse; unlike lunar eclipses, not everyone on the night side of Earth can see it.

Types of Solar Eclipses

A Partial Solar Eclipse occurs if you are standing in the penumbra; only part of the Sun is blocked.
A Total Solar Eclipse occurs if you are standing in the umbra; the entire Sun is blocked out, making it much darker.
During a total solar eclipse, the Sun’s corona becomes visible as a glowing ring.
An Annular Solar Eclipse happens if the Moon appears too small to cover the entire Sun due to varying distances; a bright ring of the Sun remains visible.

The Sun’s Corona

The corona is the Sun’s outer atmosphere, visible only when the Sun’s bright surface is totally blocked during a total eclipse.
The corona is normally too dim to see because the Sun’s main brightness overwhelms it.
Even the corona is bright enough to damage your eyes; never look directly at any stage of a solar eclipse without protection.

Effects of Orbits on Eclipses

Both the Earth's and Moon's orbits are ellipses, so their distances from each other and the Sun change.
The apparent size of the Sun and Moon changes with distance, which affects whether an eclipse is total or annular.

Key Terms & Definitions

Umbra — The darkest central part of a shadow, where the Sun is completely blocked.
Penumbra — The lighter, outer part of a shadow, where the Sun is only partly blocked.
Corona — The Sun’s outer atmosphere seen as a halo during a total solar eclipse.
Partial Solar Eclipse — Only part of the Sun is blocked by the Moon.
Total Solar Eclipse — The Moon completely blocks the Sun, showing the corona.
Annular Solar Eclipse — The Moon covers the center of the Sun, leaving a bright ring visible ("annular" means "ring").

Action Items / Next Steps

Study the differences between partial, total, and annular solar eclipses.
Remember: never look directly at the Sun or an eclipse without proper eye protection.