Key Terms
- active region
- an area on the Sun where magnetic fields are concentrated; sunspots, prominences, flares, and CMEs all tend to occur in active regions
- aurora
- light radiated by atoms and ions in the ionosphere excited by charged particles from the Sun, mostly seen in the magnetic polar regions
- chromosphere
- the part of the solar atmosphere that lies immediately above the photospheric layers
- corona
- (of the Sun) the outer (hot) atmosphere of the Sun
- coronal hole
- a region in the Sun’s outer atmosphere that appears darker because there is less hot gas there
- coronal mass ejection (CME)
- a solar flare in which immense quantities of coronal material—mainly protons and electrons—is ejected at high speeds (500–1000 kilometers per second) into interplanetary space
- differential rotation
- the phenomenon that occurs when different parts of a rotating object rotate at different rates at different latitudes
- granulation
- the rice-grain-like structure of the solar photosphere; granulation is produced by upwelling currents of gas that are slightly hotter, and therefore brighter, than the surrounding regions, which are flowing downward into the Sun
- Maunder Minimum
- a period during the seventeenth century when the number of sunspots seen throughout the solar cycle was unusually low
- photosphere
- the region of the solar (or stellar) atmosphere from which continuous radiation escapes into space
- plage
- a bright region of the solar surface observed in the light of some spectral line
- plasma
- a hot ionized gas
- prominence
- a large, bright, gaseous feature that appears above the surface of the Sun and extends into the corona
- solar flare
- a sudden and temporary outburst of electromagnetic radiation from an extended region of the Sun’s surface
- solar wind
- a flow of hot, charged particles leaving the Sun
- sunspot
- large, dark features seen on the surface of the Sun caused by increased magnetic activity
- sunspot cycle
- the semiregular 11-year period with which the frequency of sunspots fluctuates
- transition region
- the region in the Sun’s atmosphere where the temperature rises very rapidly from the relatively low temperatures that characterize the chromosphere to the high temperatures of the corona
This book was adapted from the following: Fraknoi, A., Morrison, D., & Wolff, S. C. (2016). Key Terms In Astronomy. OpenStax. https://openstax.org/books/astronomy/pages/15-key-terms under a Creative Commons Attribution License 4.0
Access the entire book for free at https://openstax.org/books/astronomy/pages/1-introduction
