Eclipse

The 1999 solar eclipse.

An eclipse is an astronomical event. It is when one object in the sky moves into the shadow of another such object. When an eclipse happens within a system of stars, like the Solar System, it makes a type of syzygy. This means that three or more objects in the sky are lined up in a straight line in the same gravitational system.^[1]

The term eclipse is most often used to describe a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the shadow of Earth. No solar eclipse can last longer than 7 minutes and 58 seconds because of the speed at which the Earth and Moon move.

When the Sun is not involved, the event is called occultation.

Etymology

The word comes from the ancient Greek noun ἔκλειψις (<span title="Lua error in package.lua at line 80: module 'Module:Language/data/ISO 639 override' not found. transliteration" class="Unicode" style="white-space:normal; text-decoration: none">ékleipsis), which is from the verb ἐκλείπω (<span title="Lua error in package.lua at line 80: module 'Module:Language/data/ISO 639 override' not found. transliteration" class="Unicode" style="white-space:normal; text-decoration: none">ekleípō). This means "to cease (stop) to exist (be there)".^[2]^[3]^[4]

Eclipse Media

Totality during the 1999 solar eclipse. Solar prominences can be seen along the limb (in red) as well as extensive coronal filaments.
The shadow of an eclipse on Earth as seen from space
Umbra, penumbra and antumbra cast by an opaque object occulting a larger light source
Types of solar eclipses
As the Earth revolves around the Sun, approximate axial parallelism of the Moon's tilted orbital plane (inclined at five degrees to the Earth's orbital plane) results in the revolution of the lunar nodes relative to the Earth. This causes an eclipse season approximately every six months, in which a solar eclipse can occur at the new moon phase and a lunar eclipse can occur at the full moon phase.
A symbolic orbital diagram from the view of the Earth at the center, with the Sun and Moon projected upon the celestial sphere, showing the Moon's two nodes where eclipses can occur.
2008-08-01 Solar eclipse progression with timestamps
Each icon shows the view from the centre of its black spot, representing the Moon (not to scale)
Geometry of a total solar eclipse (not to scale)
Moon eclipse in Belgium (Hamois).