- This article discusses astronomical eclipses. For other meanings, see Eclipse (disambiguation).
From Earth's point of view, eclipses can be:
- Lunar eclipses - the Earth obscures the Sun, from the Moon's point of view. The Moon moves through the shadow cast by the Earth. This can only happen at full moon.
- Solar eclipses - the Moon obscures the Sun, from the Earth's point of view. The Moon casts a shadow that touches the surface of the Earth. This can only happen at new moon.
Partial eclipses occur at places where only part of the luminary is covered (solar eclipses), or when only part of a body is eclipsed by the shadow (lunar eclipses). For solar eclipses, the viewer is in the penumbra part of the moon's shadow.
An annular eclipse is a total eclipse of luminary where a thin ring of light is visible around the intervening object. It is sheer coincidence that the Moon and Sun have nearly equal apparent sizes, making annular eclipses possible. Annular eclipses are ideal times for observing solar prominences.
As seen from Earth, an eclipse can only occur when the Sun, Earth and Moon are in a line. Because the plane of the orbit of the Moon is tilted with respect to the plane of the orbit of the Earth (the ecliptic), eclipses occur only when the three bodies are near the intersection of these planes: these are nodes. The Sun passes either node once a year, and eclipses occur in a period of about 2 draconic months around these times. There can be from 2 to 7 eclipses in a calendar year. They repeat according to eclipse cycles.
Eclipse is also a open source IDE (Integrated Development Environment) platform developed by IBM.