Photon Sphere Radius
r_ph = 3·G·M / c^2
What it says
The radius at which light itself orbits a black hole in a circle — one and a half times the event horizon.
Symbols
| Symbol | Quantity | Dimension |
|---|---|---|
r_ph | Photon sphere radius (m) | L |
M | Mass (kg) | M |
Work it out
Enter what you know. No account needed.
Fill in all but one: M, r_ph are all empty.
Filed under Astrophysics · derive through it in the explorer