International Space Station (ISS) transiting the Sun during the partial solar eclipse of 21st August 2017. Solar eclipses occur when the Moon passes across the Sun as seen from Earth. A total solar eclipse tracked across a narrow portion of the contiguous United States from Lincoln Beach, Oregon, in the north west, to Charleston, South Carolina, in the south east. A partial solar eclipse was visible across the entire North American continent. Solar eclipses usually occur less than once a year, and can only be seen from a small area of the Earths surface. Photographed from Ross Lake, Northern Cascades National Park, Washington, USA.NasaBill IngallsScience Photo Library