A celestial object is any object that exists in outer space, such as stars, comets, pulsars, and orbs. A pulsar is a rapidly rotating neutron STAR that emits a beam of electromagnetic radiation. A COMET is a small icy body that orbits the sun and has a visible coma and sometimes a tail. An ORB is a spherical object that orbits a larger object, such as a planet or STAR. A STAR is a luminous ball of gas held together by its own gravity.