The Astroid

The astroid is a special form of a mathematical equation called a “hypocycloid.” A hypocycloid is a curve produced by a fixed point on the circumference of a small circle of radius “b” rolling around the inside of a large circle of radius “a.”

An n-cusped hypocycloid has a/b = n. If a/b = 4, the resulting curve contains 4 cusps and is referred to as an “asteroid.”