The gases held by gravity around Earth and other planets, and can also refer to gases around stars.
CFCs are responsible for ozone layer depletion.
A celestial object that is too large to be a planet but too small to sustain hydrogen fusion reactions in its core.
A compound consisting of chlorine, fluorine, and carbon, used in refrigerants and aerosol propellants.
The pattern of temperature change over the course of a day.
A weather condition in the Pacific Ocean that affects global weather, characterized by unusually warm surface waters.
The uppermost layer of the atmosphere, where atmospheric gases can escape into outer space.
A wall or partition designed to inhibit or prevent the spread of fire.
The erosive process that reduces the size of glaciers.
The second of the three main layers in the Sun’s atmosphere, situated above the photosphere and below the corona.
The leading edge of a cooler mass of air, replacing a warmer mass of air.
The smallest unit of a substance that still acts like the main substance, which can be a single atom or a group of atoms.
A region of the Solar System beyond the orbit of Neptune, believed to contain many small icy bodies.
A nocturnal coastal breeze that blows from land to sea, caused by pressure differences.
A structure formed by diffused material in orbital motion around a massive central body.
A portion where an aircraft decreases altitude, opposite of ascent or climb.
The atmospheric temperature below which water droplets begin to condense.
The force that directly opposes the weight of an airplane and holds it in the air.
The space around a magnet where the magnetic force is active, protecting us from space weather.
The instruments that are accommodated on a spacecraft.
A type of aircraft which derives both lift and propulsion from one or more sets of horizontally revolving overhead rotors.
The pathways through which water is cycled in the terrestrial biosphere.
A glacial period characterized by lower global temperatures and ice sheet expansion.
Aurora australis is seen near the South Pole, while aurora borealis is seen near the North Pole.
To measure wind speed.
The distance north or south of the equator, measured in degrees.
The part of the Earth consisting of the crust and mantle.
The apparent shift in position of a nearby star against the background of distant objects due to Earth’s orbit around the Sun.
Fine dry or wet particles of dust, salt, or other impurities that can concentrate in a layer next to the Earth when air is stable.
The gradual boundary between the heliosphere and the interstellar gas outside our solar system.
A compact region at the center of a galaxy with much higher than normal luminosity.
The inclination of an aircraft's wing from the horizontal, especially upwards away from the fuselage.
A synthetic fiber of high tensile strength used especially as a reinforcing agent in the manufacture of tires and other rubber products.
A planet that orbits a star outside our solar system.
A cloth canopy that fills with air and allows a person or heavy object to descend slowly when dropped from an aircraft.
The bubble-like region of space dominated by the solar wind, a stream of charged particles released from the upper atmosphere of the Sun.
Frequency, equal to one cycle per second.
Water condensation occurring on surfaces below freezing, turning to ice.
A loose collection of atoms moving around each other.
The study of everything that lies beyond the Earth's atmosphere.
Natural precipitation that becomes acidic after reacting with air pollutants.
The average distance from the Earth to the sun, approximately 149,599,000 kilometers.
A rotorcraft that uses a single rotating blade.
Objects that are round and orbit the sun but cannot clear their path around it.
A small body of matter from outer space that becomes incandescent as it enters the Earth’s atmosphere.
A highly energetic explosion observed in distant galaxies, associated with the collapse of massive stars or the merger of neutron stars.
The trapping of heat in the Earth’s atmosphere by greenhouse gases, which warms the planet.
A phenomenon stating that moving air will have a lower pressure than the still air around it.
The study of the origin, evolution, and possibility of life in the universe.
Someone who travels in space.
Unusually cold sea surface temperatures across the east-central Equatorial Pacific.
A tide just after the first or third quarters of the moon when there is least difference between high and low water.
A spherical shell around our solar system that may contain more than a trillion icy bodies.
The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.
The amount of energy that passes through a unit area per unit time in a specified direction.
Part of the electromagnetic spectrum, also called gamma radiation, with high energy from events like solar flares and exploding stars.
A subject of natural science concerned with the physical processes and properties of the Earth and its surrounding space environment.
The ongoing rise in global average temperature near the Earth’s surface.
Between the stars.
Natural light displays in the Earth’s sky, typically seen in high-latitude regions.
It suggests that the universe began with an explosion of all matter from an infinitely compressed state 10 to 20 billion years ago.
The weather in some location averaged over a period of time.
The sum of all aerodynamic or hydrodynamic forces opposing the motion of a solid object moving through a fluid.
The distance light travels in one year, approximately 9.46 trillion kilometers.
An event that occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon.
A fourth state of matter where electrons are pulled free from atoms and can move independently.
That the Sun is at the center, as opposed to the Earth.
All the waters on the Earth’s surface, such as lakes and seas.
The intrinsic brightness of a celestial object as it would appear at a standard distance of 10 parsecs.
Technology used to improve the performance of optical systems by reducing wavefront distortions.
A celestial object consisting of a nucleus of ice and dust, which develops a tail of gas and dust particles when near the sun.
A type of instability that occurs when there is a velocity difference across the interface between two fluids.
A unit of distance equal to exactly 1.852 kilometers or about 6076.1 feet.
A star showing a sudden large increase in brightness and then slowly returning to its original state over a few months.
A prolonged period of excessively hot weather.
The increase in signal power produced by an amplifier.
A surface of constant gravitational potential around the Earth, averaged and perpendicular to the force of gravity.
A satellite orbiting the Earth at the same rotational speed, appearing stationary relative to the surface.
An orbit around Earth of a satellite with an orbital period that matches Earth's rotation on its axis.
A theory that unifies the electromagnetic, strong, and weak forces.
The circular orbit at approximately 35,800 km above the equator, where satellites travel at the same speed as the Earth's rotation.
The deflection of moving objects when they are viewed in a rotating reference frame.
A seasonal prevailing wind that brings heavy rains.
All the different kinds of light and energy in the universe, including radio waves, microwaves, and gamma rays.
The contradiction between the lack of evidence for extraterrestrial civilizations and high estimates for their probability.
The point in an orbit where an object is closest to the Earth.
Production of light when electricity flows through a tube filled with gas.
The amount of water vapor in the air.
A massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter.
Magnetic storms on Earth.
A multi-year surplus accumulation of snowfall resulting in a mass of ice that shows some evidence of movement in response to gravity.
The force of attraction between all masses in the universe.
A line on a map connecting points having the same temperature.
The basic building block of matter, made of protons, neutrons, and electrons.
The lowest possible temperature, at which substances contain no heat energy.
A region of space with a gravitational field so intense that no matter or radiation can escape.
The measure of the reflectivity of a surface or body, usually expressed as a percentage.
A type of matter hypothesized to account for a large part of the total mass in the universe, not directly observable by emitted radiation.
The plane of Earth’s orbit around the Sun, used as a primary reference plane for celestial coordinates.
A process that generates a liquid from a solid or gas, behaving in accordance with fluid dynamics.
The scientific study of the atmosphere and weather patterns.
Number of cycles and parts of cycles completed per second.
Water vapor content in the air and communicates changes in humidity.
A crater on a planet or satellite caused by the impact of a meteorite or other object.
An orbit where a satellite moves at the same rate as the Earth’s rotation, staying over the same spot.
Gases in the atmosphere that trap heat from the sun, including carbon dioxide, methane, and water vapor.
A large-scale atmospheric convection cell in which air rises at the equator and sinks at medium latitudes.
The study of climate, its variations, and impacts over long periods.
The process of capturing and storing atmospheric carbon dioxide.
A detachable self-contained unit of a spacecraft.
The change in frequency or wavelength of a wave for an observer moving relative to its source.
A pair of stars that appear close to each other in the sky as seen from Earth.
A natural object that travels around a bigger natural object, such as a planet or dwarf planet.
A type of stellar remnant that results from the gravitational collapse of a massive star after a supernova, made mostly of neutrons.
The galaxy that contains our Solar System.
An event focused on space education and research.
The boundary between two different air masses.
The study of the interactions between the hydrological cycle and climate.
Speeds of more than five times the speed of sound (Mach 5).
The angle of the orbit plane to the central body's equator.
Global Positioning System, a system that uses satellites to determine exact location on Earth.
An imaginary line of longitude 180 degrees east or west of the prime meridian.
Water held underground in the soil or in pores and crevices in rock.
A circle of white or colored light around the sun or moon caused by refraction through ice crystals in the atmosphere.
To reduce the velocity and increase the static pressure of a fluid passing through a system.
A position in space where the gravitational forces of a two-body system produce enhanced regions of attraction and repulsion.
It alters the motion of electricity, causing current flow in a circuit.
The gravitationally curved trajectory of an object around a point in space.
Typically caused by heavy rain.
A thick cloud of tiny water droplets suspended in the atmosphere near the Earth’s surface.
A state of motion engaged by an object in orbit, whereby constant attitude is not maintained.
The balance between the gravitational force and the pressure gradient force in a fluid.
A satellite instrument that measures and maps the Earth and its atmosphere.
The matter that exists in the space between the star systems in a galaxy.
A giant cloud of dust and gas in space, some of which are regions where new stars are being born.
A layer in the Earth’s stratosphere that absorbs most of the Sun’s harmful ultraviolet radiation.
A dry, warm, down-slope wind that occurs in the lee of a mountain range.
A half of the Earth, usually divided into northern and southern halves by the equator, or into western and eastern halves by an imaginary line passing through the poles.
The physical elements of the Earth's surface, crust, and interior.
A technique used to determine the properties of waves by analyzing the patterns created when they overlap.
A region near the equator where the trade winds of the Northern and Southern Hemispheres come together.
A method of propulsion that uses the reaction force of a high-speed jet of fluid expelled from a rocket engine.
An area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.
The observation that the farther away a galaxy is, the faster it is moving away from us.
The main body of an aircraft.
Having or representing the earth as the center, as in former astronomical systems.
A wind that results from a balance between the Coriolis force and the pressure gradient force.
Solar radiation incident upon a unit horizontal surface on or above the Earth's surface.
The layer of the Earth's atmosphere that contains a high concentration of ions and free electrons and can reflect radio waves.
The instantaneous variation of the frequency of a carrier wave in response to changes in the amplitude of a modulating signal.
A tropical cyclone with sustained winds of at least 74 mph.
A propellant combination used in a rocket engine that spontaneously ignites when its components come into contact.
A brief epoch in the early universe, just after the Big Bang, during which the universe underwent rapid expansion.
The energy above which the electromagnetic force, weak force, and strong force become indistinguishable.
The link between the control system and a satellite in orbit, tracking signals and distributing information.
A fast flowing, narrow air current found in the atmospheres of some planets, including Earth.
The luminous flux per unit area on an intercepting surface at any given point.
The nozzle and valve through which fuel is sprayed into a combustion chamber.
A force that pulls matter together.
The area or region where a particular type of plant or animal lives and grows.
A force acting briefly on a body and producing a finite change of momentum.
Part of the electromagnetic spectrum that we cannot see but can feel as heat, made of waves released by hot objects.
Between the planets in our solar system.
A device consisting of a wheel or disc mounted to spin rapidly about an axis that can alter in direction.
Flares that accelerate mostly electrons, with some protons.
The process by which an atom or a molecule acquires a charge by gaining or losing electrons.
Precipitation composed of balls or irregular lumps of ice produced in cumulonimbus clouds.
A line on a map connecting points having the same atmospheric pressure.
A wind that carries high-density air from a higher elevation down a slope under the force of gravity.
