The evolute of an astroid is an astroid twice as large. These are the equations of a non symmetric astroid. An astroid is a particular mathematical curve&colon; a hypocycloid with four cusps. A hypocycloid curve with four cusps is known as an astroid. This implies that an astroid is also a superellipse. The astroid is, therefore, a real algebraic curve of degree six. Similarly, the envelope glissette of the line segment in the example above is an astroid.