Solar physics
type: Concept
narrower: Sunspots

Sunspot groups
type: Concept
broader: Sunspots

Delta sunspots
type: Concept
broader: Sunspots

Solar active regions
type: Concept
narrower: Sunspots

Wilson effect
type: Concept
broader: Sunspots

Sunspot number
type: Concept
broader: Sunspots

Sunspot cycle
type: Concept
related: Sunspots

Sunspot flow
type: Concept
broader: Sunspots

Ephemeral active regions
type: Concept
broader: Sunspots

Maunder minimum
type: Concept
broader: Sunspots

Sunspots
type: Concept
narrower: Sunspot groups
narrower: Wilson effect
narrower: Sunspot number
narrower: Sunspot flow
narrower: Ephemeral active regions
narrower: Maunder minimum
narrower: Delta sunspots
alternative label: Sun spots
related: Sunspot cycle
related: Starspots
definition: An area seen as a dark patch on the Sun's surface. Sunspots appear dark because they are cooler (of about 4000 °C) than the surrounding photosphere (about 6000 °C). They range in size from a few hundred kilometers to several times the Earth's diameter and last from a few hours to a few months. Very small sunspots are called pores. The number of sunspots varies from maximum to minimum in about 11 years, the sunspot cycle. Their appearance during a cycle follows the Sporer law. A typical spot has a central umbra surrounded by a penumbra, although either features can exist without the other. Sunspots are associated with strong magnetic fields of 0.2 to 0.4 tesla. A given sunspot has a single magnetic polarity. The opposite polarity may be found in other sunspots or in the bright and diffuse facular region adjacent to the sunspot. The first recorded naked-eye sightings of sunspots were by Chinese astronomers in the first century B.C. Johannes Fabricius (1587-1617) was the first to argue that sunspots are areas on the solar surface.
modified: 2020-11-04T18:50:12.933Z
modified: 2020-12-16T20:39:45.185Z
broader: Solar active regions
broader: Solar physics
contributor: AAS Frey.Katie Admin

Starspots
type: Concept
related: Sunspots