Glossary

active region--Part of the solar atmosphere that is associated with a magnetic field where solar events often take place.

adiabatic expansion--The expansion  and cooling of a gas in which it neither gains or loses energy

atmosphere--The layer of gases surrounding a body in space

aurora--A collision of the solar wind with the Earth's atmosphere that causes a release of energy seen as colored lights in the sky

aurorae--Aurora plural

auroral ovals--Oval-shaped bands centered on the north and south poles where substorms and bright aurorae are observed

auroral substorm--A development of the aurora best seen in the auroral ovals that has three main phases: onset, expansion, and recovery

chromosphere--The layer of the Sun above the photosphere where the temperature begins to rise with height

composition--The types of ions that make up the solar wind

convective zone--The layer of the Sun above the radiative zone in which energy transfer continues through convection, like bubbles transfer energy in boiling water

coronal hole--An extended region of the corona that is especially low in density

core--The center of the Sun where the synthesis of helium takes place through the process of fusion

corona--The layer of the Sun above the chromosphere which is hotter than the Sun's surface and where many solar events can be seen

coronagraph--A telescope that blocks out the Sun with a black disk so that its corona is visible

coronal mass ejection--An explosion that takes place in the corona that ejects particles into the solar wind, caused by an energy release in the Sun's magnetic field

differential rotation--The difference in the pace of rotation between the polar and equatorial regions on the Sun

disk--The surface of the Sun as it is seen in the sky

electric field--The forces in action between two charged objects

filament--A mass of gas that appears as dark lines suspended over the photosphere by magnetic fields

fusion--The process by which two atoms unite to form a heavier atom in which energy is released

heliopause--The place where the influence of the Sun's magnetic field stops

heliosphere--The entire large bubble of the Sun's influence that stretches far beyond the major planets

helmet streamer--Gas from the Sun that accumulates in a closed magnetic field line and looks like a long pointed peak coming off of the Sun

interplanetary dust grains--Particles left behind by asteroids and comets, or that are leftover from the formation of the solar system

interplanetary magnetic field--The magnetic field among and between planets, brought out from the Sun by the solar wind

interstellar medium--The gas and dust that is found between the stars

ion--A particle that is charged through the gain or loss of an electron(s)

ionosphere--Region of the Earth's atmosphere that is ionized by the Sun's emissions

limb--The edge of the Sun's disk

mass spectrometer--An instrument that measures the types of ions found in the solar wind

magnetic field-- The portion of space near a body in which a magnetic force can be detected

magnetic storm--Occurs when magnetospheric substorms become strong, prolonged, and intense

magnetohydrodynamic waves--Wave motions that affect magnetic field lines in an ionized gas

magnetometer--An instrument that measures magnetic fields and sometimes the composition of the solar wind

magnetopause--The place where the influence of the Earth's magnetosphere stops

magnetosphere--The entire area of magnetic influence of a body

magnetospheric substorm--A flow of increased energy flowing from the solar wind into the magnetosphere

photons--A form of electromagnetic radiation, such as visible light or radio waves

photosphere--The layer of the Sun above the convective zone where light is emitted

pick-up ions--Neutral particles that become ions and are then "picked-up" by the solar wind from the interstellar medium and interplanetary dust grains.

plane of the ecliptic--The imaginary flat area that stretches out from the Sun's equator into space

plasma--Any ionized gas that conducts electricity and is affected by magnetic fields

prominence--A mass of cloud-like gas that rises from the Sun's chromosphere

proton cycle--The fusion reactions that take place in the Sun which make it release energy

radiative zone--The layer of the Sun above the core in which energy transfer begins through radiation

solar cycle--The period of 22 years in which the Sun's magnetic field rotates a full 360 degrees, causing its poles to switch

solar eclipse--The obstruction of the moon by the Sun that happens when the moon's orbit causes it to pass between the Sun and the Earth

solar flare--An eruption of hydrogen gas that occurs in an active region that causes a quick brightening and usually a magnetic disturbance

solar maximum--The time during the solar cycle when the Sun is out of line with its magnetic poles and turning, causing more solar activity

solar minimum--The time during the solar cycle when the Sun is in line with its magnetic poles as it has completed an 180 degree reversal, causing less solar activity

solar wind--The constant flow of charged particles coming from the Sun in all directions

solar-terrestrial relations--The way in which solar activity affects the Earth and its magnetic field

solid state detector--The plate in the time-of-flight region of the mass spectrometer that measures the kinetic energy of an ion

spicules--Fine, jet-like narrow columns of solar material found in the chromosphere that ascend into the corona

sprays--Extremely explosive ejections that take place during a solar flare at high velocities

surges--An ejection from the Sun that takes place during a solar flare that ascend and descend in a straight path

sunspots--Spots on the Sun that are dark, surrounded by lighter regions that are cooler than the photosphere