Aurora

An aurora, sometimes referred to as a polar light, is a natural light display in the sky, predominantly seen in the high latitude (Arctic and Antarctic) regions. Auroras are produced when the magnetosphere is sufficiently disturbed by the solar wind that the trajectories of charged particles in both solar wind and magnetospheric plasma, mainly in the form of electrons and protons, precipitate them into the upper atmosphere (thermosphere/exosphere), where their energy is lost. The resulting ionization and excitation of atmospheric constituents emits light of varying colour and complexity. The form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere. Proton auroras are usually observed at lower latitudes. Different aspects of an aurora are elaborated in various sections below.

World

World is a common name for the whole of human civilization, specifically human experience, history, or the human condition in general, worldwide, i.e. anywhere on Earth or pertaining to anywhere on Earth.

In a philosophical context it may refer to:

In a theological context, world usually refers to the material or the profane sphere, as opposed to the celestial, spiritual, transcendent or sacred. The "end of the world" refers to scenarios of the final end of human history, often in religious contexts.

World history is commonly understood as spanning the major geopolitical developments of about five millennia, from the first civilizations to the present.

World population is the sum of all human populations at any time; similarly, world economy is the sum of the economies of all societies (all countries), especially in the context of globalization. Terms like world championship, gross world product, world flags etc. also imply the sum or combination of all current-day sovereign states.

Tenacious D

Tenacious D is an American rock duo that was formed in Los Angeles, California in 1994. Composed of lead vocalist and guitarist Jack Black and lead guitarist and vocalist Kyle Gass, the band has released three albums – Tenacious D (2001), The Pick of Destiny (2006) and Rize of the Fenix (2012). Tenacious D's studio releases, and (as of 2006) its live performances, feature a full band lineup, including such musicians as guitarist John Konesky and bassist John Spiker. Drummer Dave Grohl (Foo Fighters, Nirvana) has played on every studio release.

The band first gained popularity in 1997 when they starred in their eponymous television series and began to support large rock acts. In 2001, they released Tenacious D, their debut album featuring a full band. The first single, "Tribute," was the band's most successful achieving their only Top 10 in any chart, until they released "The Metal", which was shown on Saturday Night Live. In 2006, they starred in, and recorded the soundtrack for, the film Tenacious D in The Pick of Destiny. In support of the film, the band went on a world tour, appearing for the first time with a full band. They released their newest album Rize of the Fenix on May 15, 2012.