See also orbital angular momentum , spin and Kepler's Laws of Motion . A spinning body also possesses spin angular momentum. A particle with precisely opposite properties to those of its matter counterpart. For example, the antimatter counterpart of an electron, known as a positron, has a positive charge, equal in strength to the negative charge of the electron. It also has an opposite spin.
Antimatter is created in a process known as pair production.
When antimatter comes into contact with its matter counterpart, the two particles are instantly annihilated by having their rest mass turned into energy and released as two photons electromagnetic radiation. The universe is predominantly composed of matter, since the laws of physics state that matter is produced with a slight but calculable bias over antimatter. The point on an elliptical orbit of a celestial object around a star where the radius has the greatest value. See also periastron . The furthest distance an object in an elliptical orbit around the Sun reaches from it.