By Julia Drake — Updated March 24, 2022
For millennia, eclipses have fascinated humanity, prompting myths and rituals across cultures. Modern astronomy now explains these dramatic events in terms of the relative positions of the Earth, Moon, and Sun.
Early societies interpreted eclipses as ominous signs. Chinese lore described a dragon devouring the Sun, while similar dragon or monster stories appeared in African, Asian, European, and Native American traditions. To ward off these perceived threats, people gathered to shout or strike instruments, producing booming noises. In some cultures, lunar eclipses were linked to earthquakes, plagues, or other calamities.
A solar eclipse occurs when the Moon passes directly between the Earth and the Sun during a new‑moon phase, aligning the three bodies. If the Moon’s apparent diameter fully covers the Sun’s disk, a total solar eclipse is seen, revealing the Sun’s corona to the naked eye. When the Moon appears slightly smaller, an annular eclipse produces a bright “ring of fire” around the Moon. The variation is due to the Moon’s elliptical orbit, which places it closer or farther from Earth at different times.
During a full moon, the Earth can block the Sun’s light, casting its shadow on the Moon. The shadow has two parts: the umbra (the darker inner zone) and the penumbra (the outer, fainter zone). Total lunar eclipses occur when the Moon fully enters the umbra, while partial eclipses involve only a portion. Penumbral eclipses happen when the Moon passes through the penumbra alone. The Earth’s atmosphere bends (refracts) sunlight, giving the Moon a reddish or coppery hue during a total eclipse.
Because the Moon’s orbital plane is tilted relative to the Earth’s orbit around the Sun, perfect alignment is rare. Typically, the Moon passes above or below the Sun at new moons, and its shadow misses the Moon at full moons. When alignment does occur, it produces either a solar or lunar eclipse. According to "The Cambridge Eclipse Photography Guide: How and Where to Observe and Photograph Solar and Lunar Eclipses" by Jay M. Pasachoff and Michael A. Covington, about seven eclipses of all types are visible worldwide each year. Total solar eclipses, however, appear roughly every 18 months.
