Total solar eclipse, corona at totality. The corona is a cloud of low-density plasma (hot ions) surrounding the Sun. Normally it is not visible, being obscured by the brightness of the Sun's visible surface, but it is revealed during a total solar eclipse. The moment of totality lasts for only a few minutes. Total solar eclipses usually occur less than once a year, and can only be seen from a small area of the Earth's surface. This total solar eclipse took place on 2 July 2019, and was visible from parts of the southern Pacific Ocean and southern South America.