Solar Eclipse
A solar eclipse occurs when the Moon passes directly between the Earth and the Sun, casting a shadow on Earth and blocking part or all of the Sun's light. A total solar eclipse, visible from within the Moon's umbra (central shadow), causes day to turn to darkness for up to about 7.5 minutes and reveals the Sun's corona — the otherwise invisible outer atmosphere. Solar eclipses occur at new Moon when the Moon's orbital plane intersects Earth's orbital plane, typically 2–5 times per year worldwide, though any specific location experiences a total eclipse roughly once every 375 years on average.
Types of solar eclipses and their characteristics
| Type | Description | Moon's Apparent Size | Max Duration | Visibility |
|---|---|---|---|---|
| Total | Sun completely blocked | Larger than Sun | ~7.5 minutes | Narrow path (~160 km wide) |
| Annular | Ring of sunlight visible | Smaller than Sun | ~12 minutes | Narrow annular path |
| Partial | Part of Sun blocked | Varies | Hours (partial phase) | Wide area on Earth |
| Hybrid | Total along part of path, annular along rest | Near equal to Sun | ~3 minutes | Rare; curved path |
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Related Terms
Inner Planet
Inner planets, also called terrestrial planets, are the four rocky planets of the Solar System — Mercury, Venus, Earth, and Mars — that orbit within the asteroid belt at distances less than about 1.5 AU from the Sun. They are characterised by solid, rocky surfaces with metallic iron cores, relatively small sizes and masses compared to the gas giants, and slower rotation in some cases due to tidal interactions with the Sun. Their proximity to the Sun means they experience intense solar radiation, shorter orbital periods, and in most cases lack large moons, making them distinct in composition and environment from the outer planets.
Gravitational Force (Astronomy)
Gravitational force in astronomy is the attractive force between any two masses, governed by Newton's Law of Universal Gravitation, which states that the force is proportional to the product of the masses and inversely proportional to the square of the distance between them. This force is responsible for holding planets in orbit around the Sun, governing the motion of moons, shaping the structure of galaxies, and dictating the trajectories of spacecraft. It is the dominant long-range force at astronomical scales and underlies phenomena from tidal locking to the formation of planetary systems.
Tidal Force
A tidal force is the differential gravitational force exerted on one body by another, arising because gravitational pull varies across the extended body — the side closer to the source experiences stronger gravity than the side farther away. This stretching effect causes Earth's ocean tides (due to the Moon and Sun), drives tidal heating on moons like Io and Europa, and can eventually lead to tidal locking, where a body's rotation period equals its orbital period. In extreme cases near compact objects, tidal forces become strong enough to disrupt and shred orbiting material, a process called spaghettification.
From Latin eclipsis and Greek ekleipsis, meaning "abandonment, forsaking, disappearance," from ekleipein ("to fail to appear, leave out"), from ek- ("out") + leipein ("to leave"). The word reflects ancient observers' perception of the Sun "abandoning" its light.