A total solar eclipse occurs when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. People located in the center of the Moon’s shadow when it hits Earth will experience a total eclipse. The sky will darken, as if it were dawn or dusk. Weather permitting, people in the path of a total solar eclipse can see the Sun’s corona, the outer atmosphere, which is otherwise usually obscured by the bright face of the Sun. During any one eclipse, totality occurs at best only in a narrow track on the surface of Earth. This narrow track is called the path of totality. The visual phases observed during a total eclipse are called:

• First contact: when the Moons limb (edge) is exactly tangential to the Suns limb.
• Second contact: when the Moon completely covers the disk of the Sun, and observers are now within the Moons umbra, the darkest part of the Moons shadow. A diamond ring effect and Bailys beads are visible just before totality.
• Totality and maximum eclipse: the Moon completely covers the disk of the Sun. Only the Suns corona is visible. This is the most dramatic stage of a total solar eclipse. At this time, the sky goes dark, temperatures can fall, and birds and animals often go quiet. The midpoint of time of totality is known as the maximum point of the eclipse.
• Third contact: when the Moon begins to move away from the Suns disk, and the diamond ring effect and Bailys beads are visible again.
• Fourth contact: when the Moons limb finally clears the Suns disk.

Total solar eclipses are rare events, occurring somewhere on Earth every 18 months on average, but they recur at any given place only once every 360 to 410 years, on average. The total eclipse lasts for only a maximum of a few minutes at any location, because the Moon is moving relative to Earth.