The planetary core consists of the innermost layer(s) of a planet.

The core may be composed of solid and liquid layers. The cores of Mars and Venus are thought to be completely solid as they lack an internally generated magnetic field. In our solar system, core size can range from about 20% (the Moon) to 85% of a planet's radius (Mercury).

Gas giants also have iron-rich cores.^{[citation needed]} Although these cores are proportionately much smaller than those of terrestrial planets, gas giants are so large that their cores can actually be larger than Earth. Jupiter's core is thought to be approximately 12 times the mass of Earth (3% of Jupiter's total mass), and the exoplanet HD 149026 b is thought to have a core approximately 70 times the mass of Earth.

It is thought that some gas giants orbiting very close to their primaries may have their atmospheres stripped away, leaving only their core behind. This as-yet hypothetical class of planets are called "Chthonian planets".

Some moons, asteroids and other minor planets may also have well-differentiated cores depending on their size and history. Jupiter's moons Io and Europa are in many ways sisters of the terrestrial planets and have very substantial cores comprising about a third of their radii. The large asteroid 4 Vesta is likewise believed to have a differentiated structure with a distinct core.

Core may refer to:

Geology (from the Greek γῆ, gê, "earth" and λόγος, logos, "study") is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates. In modern times, geology is commercially important for mineral and hydrocarbon exploration and for evaluating water resources; is publicly important for the prediction and understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change; plays a role in geotechnical engineering; and is a major academic discipline.

The study of the physical material of the Earth dates back at least to ancient Greece when Theophrastus (372-287 BCE) wrote the work Peri Lithon (On Stones). In the Roman period, Pliny the Elder wrote in detail of the many minerals and metals then in practical use, and correctly noted the origin of amber.

Chapter 14 is an American alternative metalcore rock band from Carlsbad, California currently consisting of vocalist Chad Ackerman (Destroy the Runner, As I Lay Dying, Austrian Death Machine), guitarist Tanner Sparks (Destroy the Runner), bassist Edwin Peraza, and Jonathan Knauer on drums.

Founded in 2003 by Ackerman and Sparks the band also consisted of drummer Mike Catalano (Chiodos, Destroy the Runner), guitarist Noah Slifka (In Fear and Faith) and bassist Eddie Hudson (Paper Mache). The band was unable to put together a full-length album but did complete two full U.S. tours and several demos without a label or financial backing.

After four years trying to land a record deal the band split up in 2007 when Ackerman and Sparks were offered the roles of vocalist and bassist for Destroy the Runner’s departing Kyle Setter and Jeremiah Crespo respectively. Noah Slifka went on to join In Fear and Faith the same year while Mike Catalano would join back up with Ackerman and Sparks in Destroy the Runner in 2008. Eddie Hudson moved on to play bass for the band Paper Mache. Chad explains what happened with Destroy The Runner and what Chapter 14 has for future plans