Comets and asteroids

In short: Comets and asteroids are remnants from the formation of the solar system, but they differ clearly in composition and appearance. Comets consist of ice and dust, while asteroids are usually made of rock or metal.

In more detail: As a comet approaches the sun, its ice evaporates, forming a glowing coma and often a visible tail, while asteroids remain permanently solid bodies without such outgassing.

In detail

• Origin of comets: Many come from the distant Kuiper Belt or the even more distant Oort Cloud.
• Tail: Solar wind and radiation pressure blow dust and gas away from the comet’s nucleus, always pointing away from the sun.
• Asteroid belt: Between Mars and Jupiter, millions of asteroids orbit, remnants of a planet that never formed.
• Near-Earth objects: Some asteroids cross Earth’s orbit and are therefore closely monitored (planeten-im-ueberblick).
• Meteorites: Small fragments from asteroids or comets that survive Earth’s atmosphere and strike the surface (meteoriten-und-sternschnuppen).
• Famous comets: Halley’s Comet is visible from Earth roughly every 76 years.
• Space probes: Missions such as Rosetta or OSIRIS-REx have directly studied comets and asteroids, even bringing samples back to Earth.