atmosphere: The envelope of gases surrounding Earth, another planet or a moon.
atomic: Having to do with atoms, the smallest possible unit that makes up a chemical element.
aurora: A light display in the sky caused when incoming energetic particles from the sun collide with gas molecules in a planet’s upper atmosphere. The best known of these is Earth’s aurora borealis, or northern lights. On some outer gas planets, like Jupiter and Saturn, the combination of a fast rate of rotation and strong magnetic field leads to high electrical currents in the upper atmosphere, above the planets’ poles. This, too, can cause auroral “light” shows in their upper atmosphere.
corona: The envelope of the sun (and other stars). The sun’s corona is normally visible only during a total solar eclipse, when it is seen as an irregularly shaped, pearly glow surrounding the darkened disk of the moon.
coronal holes: Parts of the sun’s corona (outer envelope) that are cooler and thinner than average.
electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
gravity: The force that attracts anything with mass, or bulk, toward any other thing with mass. The more mass that something has, the greater its gravity.
grid: (in electricity) The interconnected system of electricity lines that transport electrical power over long distances. In North America, this grid connects electrical generating stations and local communities throughout most of the continent.
magnetic field: An area of influence created by certain materials, called magnets, or by the movement of electric charges.
particle: A minute amount of something.
planet: A large celestial object that orbits a star but unlike a star does not generate any visible light.
plasma: (in chemistry and physics) A gaseous state of matter in which electrons separate from the atom. A plasma includes both positively and negatively charged particles.
poles: (in Earth science and astronomy) The cold regions of the planet that exist farthest from the equator; the upper and lower ends of the virtual axis around which a celestial object rotates.
proton: A subatomic particle that is one of the basic building blocks of the atoms that make up matter. Protons belong to the family of particles known as hadrons.
satellite: A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.
solar: Having to do with the sun or the radiation it emits. It comes from sol, Latin for sun.
solar wind: A flow of charged particles (including atomic nuclei) that have been ejected from the surface of the star, such as our sun. It can permeate the solar system. When emitted by a star other than the sun, this radiation is known as a stellar wind.
space weather: Conditions on the sun, in the solar wind and within Earth’s upper atmosphere that can affect technologies on Earth and that have the potential to endanger human health. Triggering these weather events are the stream of plasma, or solar wind, emitted by the sun. In addition, there are clouds of material spewed by the sun, known as coronal mass ejections. Together, these can contribute to large magnetic and electrical storms in Earth’s upper atmosphere.
sun: The star at the center of Earth’s solar system. It is about 27,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.
technology: The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.
weather: Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.