The stars of a cluster of stars were created together from a huge gas cloud. They are only a few light-years apart and spend their entire life in groups. Sometimes there are also outliers who eventually break away from the group and drift away. Usually, however, the stars of a cluster of stars cling to each other with their gravitation and circle around their common center.

Comets, also known as tail stars, are celestial bodies of gaseous and solid particles, which usually orbit the sun on very eccentric orbits. The actual body, the so-called core, consists of ice (frozen carbon monoxide and carbon dioxide, methane, water ice, etc.).