On August 12th, crowds across Europe and the North Atlantic region looked skyward as the Moon passed in front of the Sun. Viewers in parts of Spain, Iceland, and Greenland experienced a total solar eclipse, while much of Europe saw the Sun partially covered. For those in the path of totality, daylight diminished, and the Sun disappeared completely.

A solar eclipse occurs when the Moon moves directly between Earth and the Sun, blocking some or all of the Sun’s light. Although the Sun is about 400 times wider than the Moon, it is also roughly 400 times farther from Earth. As a result, the two objects can appear almost equivalent in size from our perspective.

However, a total eclipse can only be seen from a narrow region. As the Moon blocks sunlight, it casts a shadow on Earth. People in the central part of that shadow, called the umbra,* see the Sun completely obscured. This track across Earth’s surface is known as the path of totality. People outside the path see only a partial eclipse, with part of the Sun remaining visible.

Solar eclipses are spectacular, but they must be observed carefully. Except during totality, looking directly at the Sun, even when most of it is covered, can permanently damage the eyes. Ordinary sunglasses do not provide adequate protection. Instead, observers should use certified eclipse glasses or solar viewers. Indirect viewing methods, such as a pinhole projector, are safe.

Solar eclipses should not be confused with lunar eclipses. During a solar eclipse, the Moon passes between Earth and the Sun. During a lunar eclipse, on the other hand, Earth moves between the Sun and Moon, causing Earth’s shadow to fall across the lunar surface. Both events require precise alignment, but each produces a different phenomenon.

* umbra 본그림자 (빛을 받지 못해 아주 깜깜하게 나타나는 그림자)