Mass concentration (astronomy)

In astronomy, astrophysics and geophysics, a mass concentration (or mascon) is a region of a planet's or moon's crust that contains a large positive gravity anomaly.

In general, the word "mascon" can be used as a noun to refer to an excess distribution of mass on or beneath the surface of an astronomical body (compared to some suitable average), such as is found around Hawaii on Earth.

Theoretical considerations imply that a topographic low in isostatic equilibrium would exhibit a slight negative gravitational anomaly.

Since their identification in 1968 by Doppler tracking of the five Lunar Orbiter spacecraft,[4] the origin of the mascons beneath the surface of the Moon has been subject to much debate, but they are now regarded as being the result of the impact of asteroids during the Late Heavy Bombardment.

This discovery observed the consistent 1:1 correlation between very large positive gravity anomalies and depressed circular basins on the Moon.

This fact places key limits on models attempting to follow the history of the Moon's geological development and explain the current lunar internal structures.

Lunar orbital effects principally resulting from the strong gravitational perturbations of the mascons were ultimately revealed as the cause.