What is a solar eclipse?

A solar eclipse happens when the Sun, Moon and Earth are perfectly aligned. The Moon blocks light from the Sun and casts a shadow on Earth. The eclipse is visible to anybody within this shadow.

A solar eclipse can be either total or partial. During a total solar eclipse, the Sun, Moon and Earth are perfectly aligned and the Moon covers the entire disc of the Sun. During a partial solar eclipse, the three are not perfectly aligned, so only part of the Sun is covered by the Moon – it looks as though the Moon takes a bite from the Sun!

Solar eclipses occur about every 16 months and ‘totality’ (when the Sun is completely covered by the Moon) can last up to seven and a half minutes depending on the Earth-Moon-Sun geometry. Considering that the Moon takes 28 days to orbit Earth, why do we not see a solar eclipse every month? Because the orbit of the Moon around Earth is tilted, so the Moon often crosses above or below the imaginary line connecting the Sun and Earth. It is only when the Moon crosses this line that we see a solar eclipse.

Discover more about eclipses here.