# Does this video show a water droplet in gravitational orbit?

Andrew Rader, an author and engineeer, tweeted a GIF video showing a droplet of water rotating around some sort of probe.

Everything has gravity - here's a droplet of water orbiting a needle in 0G.

No source is provided. The scale is unclear. The result is counter-intuitive, and I am skeptical.

I realize that there is a stitching point somewhere to make the GIF repeat. I'm not challenging that aspect.

Does this video show a water droplet in (gravitational) orbit around a needle?

• I'm curious now quite how slow a water droplet would have to travel to actually orbit a needle (assuming you could actually set this system up far enough from any other masses for it to work at all.) – reirab May 1 '16 at 6:23
• @reirab For a rough approximation let's take a much more massive needle (say, M = 0.1 kg), also join all its mass in a ball (the mass of a needle is mostly "far away" and thus pulls less). And let the droplet orbit at a distance of just 1 mm. Then the orbital speed for a circular orbit is approximately sqrt(G M / r) or about 80 micrometers per second (i.e., during a full day it moves by just about half a centimeter) – Hagen von Eitzen May 1 '16 at 8:09
• The camera has more gravity than the water droplet. – PyRulez May 1 '16 at 12:27
• @PyRulez depends how close the camera is to the needle... – Nathan Osman May 2 '16 at 16:27
• Can we get this image embedded in this question so we don't lose it to link-rot? – Almo May 3 '16 at 19:20