View an animation of a brown dwarf surrounded by a swirling disk of planet-building dust

Encyclopædia Britannica, Inc.

Learn how alpacas (Vicugna pacos) are raised in the Andes Mountains of Peru and Bolivia to be sheared every two years so that the wool can be shipped to cities such as Arequipa, Peru, for processing into fine fabrics.

Contunico © ZDF Studios GmbH, Mainz

Learn about lightning and thunder.

Encyclopædia Britannica, Inc.

The average tornado has a short lifespan—but large potential for destruction.

© MinutePhysics (A Britannica Publishing Partner)

Learn how the solar system, which formed from a roughly spherical cloud, became flat.

© Open University (A Britannica Publishing Partner)

A discussion of the Nice model (named for Nice, France) of the formation of the orbital structure of the outer planets and the Kuiper belt. The Nice model also accounts for the age of some Moon rocks.

Encyclopædia Britannica, Inc.

Discussion of four attempts to explain the structure of the solar system, from Aristotle to Johannes Kepler.

Encyclopædia Britannica, Inc.

Copernicus's theory of the solar system.