Total solar eclipse around totality. Time-lapse sequence of 11 images from before totality (lower left) to totality (centre) and after totality (upper right) for a total solar eclipse. Total solar eclipses occur when the Moon passes directly in front of the Sun. Total solar eclipses usually occur less than once a year, and can only be seen from a small area of the Earth's surface. At totality, the solar atmosphere (corona) becomes visible. This total solar eclipse was observed on 21 August 2017. Totality lasted for just over 2.5 minutes.