a black hole and an orbiting star, bending the grid of space
What you're seeing
The cyan grid is a 2-D slice of space. Mass curves it — every line bends
toward mass. (Hugely exaggerated so you can see it.)
The black disk is the event horizon: grid lines that get too close converge
into it and never come back out. The bright ring is light circling the
photon sphere.
The orange star is not a black hole — but it has mass, so it drags its own
smaller dent through spacetime as it moves. Watch the grid flex around it.
(The black hole wobbles too: both bodies orbit their common centre of mass.)
The orbit traces a rosette — perihelion precession, the same
general-relativity effect measured in Mercury's orbit.
The faint spiral ripples are gravitational waves radiated by the pair,
strongest when the orbit is tight and fast.
Click anywhere to relocate the star. If it crosses the horizon it is
swallowed, and a new star appears.