15.6: Key Terms
- Page ID
- 66594
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- 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