eclipse

The two types of eclipse: lunar and solar. A lunar eclipse occurs when the Moon passes through the shadow of the Earth. A solar eclipse occurs when the Moon passes between the Sun and the Earth, blocking out the Sun's light. During a total solar eclipse, when the Moon completely covers the Sun, the Moon's shadow sweeps across the Earth's surface from west to east at a speed of 3,200 kph/2,000 mph.

During a total solar eclipse the Sun's corona (halo of hot gases) becomes visible.

A total solar eclipse occurs when the Moon moves across the face of the Sun so that the Moon's shadow falls over the Earth. As a result of the elliptical orbits of the Earth around the Sun, and the Moon around the Earth, the Moon will not always completely cover the Sun, and the Sun's rim sometimes remains visible around it. This type of eclipse is known as an annular eclipse.

Total solar eclipse showing solar corona.

A solar eclipse occurs when the Moon, passing between the Earth and the Sun, blocks the Sun's rays and casts a shadow on the Earth. A lunar eclipse occurs when the Earth, passing between the Moon and Sun, blocks the Sun's rays and casts a shadow on the Moon. Both solar and lunar eclipses can be partial or total.

Passage of one astronomical body through the shadow of another. The term is usually used for solar and lunar eclipses. A solar eclipse occurs when the Moon is between the Earth and the Sun (which can happen only at new Moon), the Moon blocking the Sun's rays and casting a shadow on the Earth's surface. A lunar eclipse occurs when the Earth is between the Moon and the Sun (which can happen only at full Moon), the Earth blocking the Sun's rays and casting a shadow on the Moon's surface.

During a total solar eclipse the Moon appears to cover the Sun's disc completely, as viewed from a small region around the centre of the Moon's shadow. In this area day turns into night. A total solar eclipse can last up to 7.5 minutes, and the Sun's corona can be seen. Between two and five solar eclipses occur each year but each is visible only in the band of the Earth's surface traversed by the Moon's shadow. Away from the centre of the shadow, the solar eclipse is partial; sunlight reaches the Earth around the edge of the Moon. When the Moon is at its furthest from the Earth it does not completely cover the face of the Sun, leaving a ring of sunlight visible. This is an annular eclipse (from the Latin word annulus meaning ‘ring’).

Lunar eclipses can also be partial or total. Total lunar eclipses last for up to 100 minutes; the maximum number each year is three. A lunar eclipse is visible from the whole night-time hemisphere of the Earth.

Other bodies can be eclipsed. For example, Jupiter's satellites can be eclipsed by Jupiter itself. An eclipse of a star by a body in the Solar System is also called an occultation.