Total solar eclipse, totality and diamond ring effects. Time-lapse sequence of three images showing just before (left), during (centre) and just after (right) totality during a total solar eclipse. The diamond ring effects are seen just before and just after totality, when a tiny fragment of the solar disc flares out from behind the Moon for a few seconds, looking like a diamond on a ring. A few minutes later, as the Moon completely covers the Sun, the solar corona (a cloud of plasma that surrounds the Sun) becomes visible, as seen here. 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 was observed from the USA on 21 August 2017. Totality lasted for just over 2.5 minutes. Photographed from Idaho, USA.