World is used to describe the whole human civilization, specifically history and the human experience. In general usage, Earth is considered as the world. The term ‘universe’ refers to everything including...

A planet is an object that orbits the Sun in an elliptical orbit, has compounded its matter in a spherical shape, and has cleared its orbit of other debris. While, a dwarf planet also orbits the Sun, has...

A dwarf planet is “a celestial body in direct orbit of the Sun that is massive enough for its shape to be controlled by gravitation, but that unlike a planet has not cleared its orbital region of other objects...

A "planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly...

A dwarf planet is “a celestial body in direct orbit of the Sun that is massive enough for its shape to be controlled by gravitation, but that unlike a planet has not cleared its orbital region of other objects...