Alfvén wave: A type of magnetic wave that can develop in hot plasma.
Antarctica: A continent mostly covered in ice, which sits in the southernmost part of the world.
arc: A curve, often mapping out what appears to be part of a circle.
atmosphere: The envelope of gases surrounding Earth, another planet or a moon.
atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
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.
aurora borealis: Also known as the northern lights, this light display in the Northern Hemisphere sky is caused when incoming energetic particles from the sun collide with gas molecules in Earth’s upper atmosphere.
comet: A celestial object consisting of a nucleus of ice and dust. When a comet passes near the sun, gas and dust vaporize off the comet’s surface, creating its trailing “tail.”
crest: The highest part of a hill, a mountain or a swell of water. (in physics) The top, or highest point, in a wave.
diffuse: adj.) To be spread out thinly over a great area; not concise or concentrated. (v) To spread light or to broadly release some substance through a liquid (such as water or air) or through some surface (such as a membrane).
distort: (n. distortion) To change the shape or image of something in a way that makes it hard to recognize, or to change the perception or characterization of something (as to mislead).
ejection: A sudden or forceful removal or jettisoning of something from its position, container or housing.
electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
equator: An imaginary line around Earth that divides Earth into the Northern and Southern Hemispheres.
Europa: One of the moons of Jupiter and the sixth-closest satellite to the planet. Europa, 1,951 miles across, has a network of dark lines on a bright, icy surface.
excite: (in chemistry and physics) To transfer energy to one or more outer electrons in an atom. They remain in this higher energy state until they shed the extra energy through the emission of some type of radiation, such as light.
field: (in physics) A region in space where certain physical effects operate, such as magnetism (created by a magnetic field), gravity (by a gravitational field), mass (by a Higgs field) or electricity (by an electrical field).
frequency: The number of times some periodic phenomenon occurs within a specified time interval. (In physics) The number of wavelengths that occurs over a particular interval of time.
friction: The resistance that one surface or object encounters when moving over or through another material (such as a fluid or a gas). Friction generally causes a heating, which can damage a surface of some material as it rubs against another.
gale: A very strong wind at sea or coming off of the sea. To qualify as a gale, winds must be at least 51 to 102 kilometers per hour (32 to 63 miles per hour).
gas giant: A giant planet that is made mostly of helium and hydrogen, which on Earth are gases. Jupiter and Saturn are gas giants.
Greenland: The world’s largest island, Greenland sits between the Arctic Ocean and North Atlantic. Although it is technically part of North America (sitting just east of Northern Canada), Greenland has been linked more politically to Europe. Ice covers roughly 80 percent of Greenland. Indeed, the Greenland ice sheet is the world’s largest. If its frozen water were to melt, it could raise sea levels around the world by 6 meters (about 20 feet).
Iceland: A largely arctic nation in the North Atlantic, sitting between Greenland and the western edge of Northern Europe. Its volcanic island was settled between the late 800s and 1100 by immigrants from Norway and Celtic lands (ones governed by the Scots and Irish). It is currently home to roughly a third of a million people.
infrared: A type of electromagnetic radiation invisible to the human eye. The name incorporates a Latin term and means “below red.” Infrared light has wavelengths longer than those visible to humans. Other invisible wavelengths include X-rays, radio waves and microwaves. Infrared light tends to record the heat signature of an object or environment.
Jupiter: (in astronomy) The solar system’s largest planet, it has the shortest day length (9 hours, 55 minutes). A gas giant, its low density indicates that this planet is composed mostly of the light elements hydrogen and helium. This planet also releases more heat than it receives from the sun as gravity compresses its mass (and slowly shrinks the planet).
magnetic field: An area of influence created by certain materials, called magnets, or by the movement of electric charges.
mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.
moon: The natural satellite of any planet.
New Zealand: An island nation in the southwest Pacific Ocean, roughly 1,500 kilometers (some 900 miles) east of Australia. Its “mainland” — consisting of a North and South Island — is quite volcanically active. In addition, the country includes many far smaller offshore islands.
nitrogen: A colorless, odorless and nonreactive gaseous element that forms about 78 percent of Earth's atmosphere. Its scientific symbol is N. Nitrogen is released in the form of nitrogen oxides as fossil fuels burn. It comes in two stable forms. Both have 14 protons in the nucleus. But one has 14 neutrons in that nucleus; the other has 15. For that difference, they are known, respectively, as nitrogen-14 and nitrogen-15 (or 14N and 15N).
oxygen: A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).
parallel: An adjective that describes two things that are side by side and have the same distance between their parts. In the word “all,” the final two letters are parallel lines. Or two things, events or processes that have much in common if compared side by side.
particle: A minute amount of something.
phenomena: Events or developments that are surprising or unusual.
photon: A particle representing the smallest possible amount of light or other type of electromagnetic radiation.
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. (in medicine) The colorless fluid part of blood.
plume: (in biology) A single large feather. (in environmental sciences) The movement of some gas or liquid, under the direction of gravity, winds or currents. It may be in air, soil or water. It gets its name from the fact that it tends to be long and relatively thin, shaped like a large feather. (in geology) Fluids (air, water or magma typically) that move, largely intact, in a feather-like shape over long distances.
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. (in physics and electrical engineering) The ends of a magnet. (in chemistry) two areas of opposite electrical charge, one positive and one negative.
Saturn: The sixth planet out from the sun in our solar system. One of the two gas giants, this planet takes 10.6 hours to rotate (completing a day) and 29.5 Earth years to complete one orbit of the sun. It has at least 82 moons. But what most distinguishes this planet is the broad and flat plane of bright rings that orbit it.
shroud: A cloth sometimes used in burials to cover the body. It can also mean any cover that drapes over something, hiding its details.
Siberia: A region in northern Asia, almost all of which falls within Russia. This land takes its name from the language of the Tatar people, where Siber means sleeping land. This region is vast. It has become famous for its long, harsh winters, where temperatures can fall to −68° Celsius (−90° Fahrenheit).
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. This is called a stellar wind, when emitted by a star other than the sun.
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.
Tasmania: A major, mountainous island of Australia, south of the eastern part of the mainland across the Bass Strait. Until 1856, Tasmania had been known as Van Diemen's Land. Home to nearly 500,000 people, it’s capital city is Hobart. The name also refers to a state in Australia that comprises this island and several smaller ones.
thermal: Of or relating to heat. (in meteorology) A relatively small-scale, rising air current produced when Earth’s surface is heated. Thermals are a common source of low level turbulence for aircraft.
thermosphere: An upper region of the atmosphere that extends from 85 to 600 kilometers (53 to 372 miles) above Earth’s surface. In the thermosphere, temperature increases with height because of the sun’s energy. It's upper boundary is known as the thermopause.
ultraviolet: A portion of the light spectrum that is close to violet but invisible to the human eye.
unique: Something that is unlike anything else; the only one of its kind.
velocity: The speed of something in a given direction.
wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.
wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.
X-ray: A type of radiation analogous to gamma rays, but having somewhat lower energy.