Glossary term: Sunspot

Also known as starspot

Description: A sunspot is a temporary cool region, caused by a strong magnetic field in the Sun's photosphere. As they are cooler than the surrounding photosphere, sunspots can be seen through a telescope as dark patches/blotches on the surface of the Sun. Sunspots range in size from tens of kilometers across to over a hundred thousand kilometers across. They can persist for timescales between a few days and a few months. Other stars are also thought to have spots caused by their magnetic fields.

Related Terms:

See this term in other languages

Term and definition status: This term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

Related Media

Image showing groups of sunspots as dark patches which lie in bands above and below the Sun's equator


Caption: In this image the sun peppered with groups of sunspots over almost nine days between July and August 2012. The sunspots seen in this image have been sources of the solar flares and coronal mass ejections (CME). In this image particulary, the sun is approaching solar maximum in its cycle (solar cycle), where we see many spots forming along the suns' equator. These sunspots and activity are seen in the southern hemisphere, before then most of the activity was on the northern hemisphere.
Credit: NASA/SDO/HMI credit link
License: PD Public Domain icons