Solar vs Lunar Eclipses: What’s the Difference?

Solar eclipse: the Moon blocks the Sun

• A solar eclipse happens when the Moon passes between the Sun and Earth, so it can only occur at new moon. The Moon’s shadow is small compared with Earth, so a total solar eclipse is only visible from a narrow path, and totality at any one spot lasts at most about seven and a half minutes.

• Types: total (the Moon covers the whole Sun), annular (the Moon is too far away to cover it, leaving a bright “ring of fire”), partial (only part of the Sun is covered), and the rare hybrid, which changes between total and annular along its path.

Lunar eclipse: Earth’s shadow falls on the Moon

• A lunar eclipse happens when Earth passes between the Sun and the Moon, so it can only occur at full moon. Anyone on the night side of Earth can see it, which is why lunar eclipses are seen by far more people than solar ones.

• During a total lunar eclipse the Moon usually turns copper-red, because sunlight bent through Earth’s atmosphere still reaches it. That is the “blood moon.”

Why eclipses don’t happen every month

The Moon’s orbit is tilted about 5° compared with Earth’s orbit around the Sun. Most months the new and full moons pass above or below the Sun–Earth line. Eclipses only happen in “eclipse seasons,” about every six months, when the alignment is close enough. Every year has at least four eclipses, two of them solar.

Watching safely

• Lunar eclipses are completely safe to watch with your eyes, binoculars, or a telescope.

• Never look at a solar eclipse without proper eye protection, except during the brief moment of totality. Regular sunglasses are not enough; use certified eclipse glasses (ISO 12312-2) or a pinhole projector. Cameras, binoculars, and telescopes need their own solar filters.