Equations · equation

Schwarzschild Radius

Astrophysics · 1916

Equation: r_s = 2GM/c²
Field: Astrophysics
Named After: Karl Schwarzschild
Symbols: r_s the event-horizon radius · G gravitational constant · M mass · c speed of light
Year: 1916

Significance

Squeeze any mass inside this radius and not even light escapes — a black hole. Derived from Einstein's field equations within months of their publication, by an astronomer serving on the Russian front. For the Sun: three kilometres; for Earth: nine millimetres.

Timeline

Black Holes Evaporate The Last Black Holes Go

Celestial Objects

Sun

Theories

Quantum Gravity Holographic Principle Black Hole Thermodynamics General Relativity

Related

Escape Velocity Einstein Field Equations Chandrasekhar Limit Gravitational Time Dilation

Instruments

Keck Observatory Chandra X-ray Observatory Very Large Telescope (VLT)

Constants

Solar mass Newtonian constant of gravitation Speed of light in vacuum

Requires

Einstein Field Equations

Spectral Types

O-type Stars

Referenced by

constant

Newtonian constant of gravitation Solar mass Speed of light in vacuum

equation

Chandrasekhar Limit Einstein Field Equations Escape Velocity Gravitational Time Dilation

event

Black Holes Evaporate The Last Black Holes Go

instrument

Chandra X-ray Observatory Keck Observatory Very Large Telescope (VLT)

theory

Black Hole Thermodynamics General Relativity Holographic Principle Quantum Gravity

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From the Equations database in Notion, last edited 2026-08-26. This page is the row, rendered by the build; nothing on it is written by hand.