Gravitational Lensing

Point-mass gravitational lens bending light rays. Drag the lens (circle) or source (star). When aligned, an Einstein ring appears.

Controls

Einstein radius:
θ_E = √(4GM·D_ls/(c²·D_l·D_s))

Deflection angle:
α = 4GM/(c²b) — twice Newton!

Click canvas to move lens.
Drag works too.
θ_E (px): —
Magnification: —