Roche limit

[ rohsh; French rawsh ]

noun

, Astronomy.

1. the minimum distance below which a moon orbiting a celestial body would be disrupted by tidal forces or below which a moon would not have formed.

Roche limit

/ rɒʃ /

noun

1. astronomy the distance from the centre of a body, such as a planet, at which the tidal forces are stronger than the mutual gravitational attraction between two adjacent orbiting objects

Roche limit

/ rōsh /

1. The shortest distance at which a satellite not held together by any force other than its own gravity can orbit another celestial body without being torn apart by the tidal force between them. The distance depends on the densities of the two bodies and the orbit of the satellite. If the satellite and the object are of similar densities, the Roche limit is about two and a half times the radius of the larger object. Since most natural satellites are rigid bodies, their tensile strength allows them to orbit much closer than their Roche limit; however, rigid bodies too may be broken up by tidal forces. The rings surrounding Saturn and the other gas giants in the outer solar system may be the orbiting debris of moons that approached much closer than the Roche limit and were fragmented by tidal forces. The limit is named after the French mathematician Edouard Roche (1820–83).

Word History and Origins

Origin of Roche limit¹

1885–90; named after French astronomer Édouard Roche (1820–83), who first calculated it

Word History and Origins

Origin of Roche limit¹

C19: named after E. A. Roche (1820–83), French mathematician

Example Sentences

The scientists behind the study believe the rings may have been created by intense meteoric bombardment of Earth, followed by a close encounter with a large asteroid passing through the Earth's Roche limit, which then created a ring of debris.

From Salon

Both rings occur in locations near what are known as resonances with Weywot, and the resonances may turn out to be more important than the Roche limit for determining whether rings turn into moons or remain as rings.

From New York Times

Like the first ring around Quaoar, announced by a team of astronomers in February, the second ring lies beyond what is known as the Roche limit.

From New York Times

Thus, a ring within the Roche limit would tend to remain a ring, while a ring of debris outside the Roche limit would usually coalesce into a moon.

From New York Times

For Quaoar, the Roche limit is calculated to be 1,100 miles.

From New York Times