Twelve different Grand Saros eclipse series are now occurring, with the one producing the eclipses of 1937, 1955, 1973, 1991, and 2009 having durations near the 7.5 minute limit.

Every eclipse begins at sunrise at some point in its track and ends at sunset about half way around the world from the start point. Partial solar eclipses can be seen up to 3,000 miles from the track of totality. Before the advent of modern atomic clocks, studies of ancient records of solar eclipses allowed astronomers to detect a 0.001 second per century slowing down in Earth’s rotation.

Total solar eclipses happen because the Sun is near one of the nodes of the lunar orbit, and the Moon is at perigee at this node at the same time. Annular solar eclipses happen because the Sun is near one of the nodes of the lunar orbit, and the Moon is at apogee at this node at the same time. Shadowbands are often seen on the ground as totality approaches.

Light filtering through leaves on trees casts crescent shadows as totality approaches.
Local animals and birds often prepare for sleep or behave confusedly during totality.
Local temperatures often drop 20 degrees or more near totality.During totality, the horizon is illuminated in a narrow band of light, because an observer is seeing distant localities not under the direct umbra of the Moon’s shadow.