Gases near a dying star in the Helix Nebula. This nebula is located in the Aquarius constellation. Each knot of gas is several billion miles across. Credit: C. Robert O'Dell and Kerry P. Handron [Rice University], NASA.
Why does a returning boomerang come back?
When most of us think of boomerangs, we imagine somebody throwing a curved stick that eventually turns around and comes right back to the thrower's hand. This device is simply amazing, and a wonderful application of some laws of physics relating to aerodynamic lift and angular momentum.