Between the planets in our solar system.
The leading edge of a cooler mass of air, replacing a warmer mass of air.
The lowest possible temperature, at which substances contain no heat energy.
A structure formed by diffused material in orbital motion around a massive central body.
A nocturnal coastal breeze that blows from land to sea, caused by temperature differences between land and water.
The study of the chemical processes and substances that occur in biological and geological contexts.
A celestial object that is too large to be a planet but too small to sustain hydrogen fusion reactions in its core.
Rocks floating around in space, varying in size from that of a pick-up truck to hundreds of miles across.
The average distance from the Earth to the sun, approximately 149,599,000 kilometers.
The study of climate, its variations, and impacts over long periods.
Aurora australis refers to the southern lights near the South Pole, while aurora borealis refers to the northern lights near the North Pole.
An area of low pressure where winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
The distance north or south of the equator, measured in degrees.
They are used in refrigerants and aerosol propellants.
The intrinsic brightness of a celestial object as it would appear at a standard distance of 10 parsecs.
A wall or partition designed to inhibit or prevent the spread of fire.
The plane of Earth’s orbit around the Sun, used for celestial coordinates.
The branch of physics dealing with electric charges, currents, and magnetic fields.
Two identical spin-1/2 particles cannot have the same position and velocity.
An almost colorless, gaseous form of oxygen with an odor similar to weak chlorine.
Referring to regions outside the Milky Way Galaxy.
A force acting briefly on a body and producing a finite change of momentum.
The shadow cast by the Earth or moon over an area experiencing a partial eclipse.
The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.
CFCs are responsible for ozone layer depletion.
A type of matter hypothesized to account for a large part of the total mass in the universe, not directly observable by emitted radiation.
A compact region at the center of a galaxy that has a much higher than normal luminosity.
The rate at which the temperature of an air parcel changes as it moves vertically.
The part of the Earth consisting of the crust and mantle.
An event that occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon.
Each type of matter particle has a corresponding antiparticle; when they collide, they annihilate, leaving only energy.
The pattern of temperature change over the course of a day.
A prolonged period of abnormally low rainfall.
A unit of distance equal to exactly 1.852 kilometers or about 6076.1 feet.
Production of light when electricity flows through a tube filled with a type of gas.
The bubble-like region of space dominated by the solar wind, a stream of charged particles released from the upper atmosphere of the Sun.
The wearing away of material caused by external forces.
A massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter.
A glacial period characterized by lower global temperatures and ice sheet expansion.
The apparent shift in position of a nearby star against the background of distant objects due to Earth’s orbit around the Sun.
The circular orbit at approximately 35,800 km above the equator where satellites appear stationary to an observer on Earth.
The erosive process that reduces the size of glaciers.
A vehicle whose blades rotate in a horizontal plane due to aerodynamic forces alone, creating lift.
A position in space where the gravitational forces of a two-body system produce enhanced regions of attraction and repulsion.
Technology used to improve the performance of optical systems by reducing the effect of wavefront distortions.
A large body of air with uniform temperature and humidity characteristics.
The process of capturing and storing atmospheric carbon dioxide.
The climate of a very small or restricted area, differing from the surrounding climate.
Electromagnetic radiation with wavelengths between about 1000 micrometers and one meter, part of the electromagnetic spectrum.
The inclination of an aircraft's wing from the horizontal, especially upwards.
A prolonged period of excessively hot weather.
A type of aircraft which derives both lift and propulsion from one or more sets of horizontally revolving overhead rotors.
A tide just after the first or third quarters of the moon when there is least difference between high and low water.
Organisms interacting with their physical environment.
Frequency, equal to one cycle per second.
A tropical cyclone with sustained winds of at least 74 mph.
An imaginary gigantic flat plate containing an Earth satellite's orbit.
A propellant combination used in a rocket engine that spontaneously ignites when its components come into contact.
A crater on a planet or satellite caused by the impact of a meteorite or other object.
The physical elements of the Earth's surface, crust, and interior.
Solar radiation incident upon a unit horizontal surface on or above the Earth's surface.
The study of everything that lies beyond the Earth's atmosphere.
The basic building block of matter, made of protons, neutrons, and electrons.
A region of the Solar System beyond the orbit of Neptune, believed to contain many small icy bodies.
The development or strengthening of cyclonic circulation in the atmosphere.
A region of space having 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.
The atmospheric temperature below which water droplets begin to condense.
It is the only known life-habitable planet.
A weather condition in the Pacific Ocean affecting global weather patterns.
A star showing a sudden large increase in brightness and then slowly returning to its original state over a few months.
A device designed to control the direction or characteristics of a fluid flow as it exits or enters an enclosed chamber.
A highly energetic explosion observed in distant galaxies, associated with the collapse of massive stars or the merger of neutron stars.
The study of the history of the oceans in the geological past.
The study of past climates using evidence from tree rings, ice cores, and other sources.
A celestial object consisting of a nucleus of ice and dust, with a tail of gas and dust particles when near the sun.
The scientific method of dating tree rings to the exact year they were formed.
A mechanical device for moving or controlling something.
A detachable self-contained unit of a spacecraft.
Two hydrogen atoms and one oxygen atom, written as H2O.
A natural object that travels around a bigger natural object, such as a planet or dwarf planet.
A measure of how an orbit deviates from being circular.
An extremely light (possibly massless) particle that is affected only by the weak force and gravity.
A thick cloud of tiny water droplets suspended in the atmosphere near the Earth’s surface.
The number of cycles and parts of cycles completed per second.
A spherical shell around our solar system that may contain more than a trillion icy bodies.
The main body of an aircraft.
The study of the possibility and nature of life on other planets.
A layer in the Earth’s stratosphere that absorbs most of the Sun’s harmful ultraviolet radiation.
The point in an orbit where an object is closest to the Earth.
A quantity measuring the influence of a substance on the magnetic flux in the region it occupies.
The measurement of light intensity, often used in the study of stars and other celestial objects.
A force that pulls matter together.
The link between the control system and a satellite in orbit, tracking signals and distributing information.
The second of the three main layers in the Sun’s atmosphere, situated above the photosphere and below the corona.
The deflection of moving objects when viewed in a rotating reference frame.
A synthetic fibre of high tensile strength used especially as a reinforcing agent in the manufacture of tyres and other rubber products.
The study of objects moving through the air that have been given a short-lived acceleration.
The force that directly opposes the weight of an airplane and holds it in the air.
The total amount of greenhouse gases emitted by an individual, organization, event, or product.
The study of the origin, evolution, and possibility of life in the universe.
Any portion where an aircraft decreases altitude, opposite of an ascent.
A dry, warm, down-slope wind that occurs in the lee of a mountain range.
A type of stellar remnant that results from the gravitational collapse of a massive star after a supernova, made mostly of neutrons.
When a celestial body passes in front of a more distant star or object, obscuring it from sight.
The pathways through which water is cycled in the terrestrial biosphere.
The balance between the gravitational force and the pressure gradient force in a fluid.
One component of fuel used to support the combustion of a rocket propellant.
The increase in the volume of fuel on combustion in the cylinder.
A cloth canopy that fills with air and allows a person or heavy object to descend slowly when dropped from an aircraft.
The contradiction between the lack of evidence for extraterrestrial civilizations and their high probability.
A tiny amount or small piece of something.
A wind that results from a balance between the Coriolis force and the pressure gradient force.
The ongoing rise in global average temperature near the Earth’s surface.
A large body in outer space that circles around the sun or another star.
The gases held by gravity around Earth and other planets, and can also refer to gases around stars.
Natural light displays in the Earth’s sky, typically seen in high-latitude regions.
The frozen water part of the Earth system, including glaciers and sea ice, affecting climate and weather.
The scientific study of the atmosphere and weather patterns.
A weather system with high atmospheric pressure at its center.
To reduce the velocity and increase the static pressure of a fluid.
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 seasonal prevailing wind that brings heavy rains.
That the Sun is at the center, as opposed to the Earth.
A subatomic particle with no net electric charge and a mass slightly larger than that of a proton.
A state of motion engaged by an object in orbit, whereby constant attitude is not maintained.
The circle around a planet that is equidistant from its poles.
Water condensation occurring on surfaces below freezing, turning to ice.
The increase in signal power produced by an amplifier.
A planet that orbits a star outside our solar system.
The luminous flux per unit area on an intercepting surface at any given point.
A surface of constant gravitational potential around the Earth, averaged to be perpendicular to the force of gravity.
A satellite orbiting the Earth at the same rotational speed, appearing stationary relative to the surface.
A technique used to determine the properties of waves by analyzing the patterns created when they overlap.
A theory that unifies the electromagnetic, strong, and weak forces.
A unit or 'particle' of electromagnetic energy, or light.
A region near the equator where the trade winds of the Northern and Southern Hemispheres come together.
A domed building in which images of stars, planets, and constellations are projected for public entertainment or education.
The weather in some location averaged over a period of time.
The process by which one substance takes in or absorbs another.
An instrument for measuring atmospheric pressure.
The distance light travels in one year, approximately 9.46 trillion kilometers.
The space around a magnet where the magnetic force is active, protecting Earth from space weather.
The sum of all aerodynamic or hydrodynamic forces opposing the motion of an object.
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 study of the interactions between the hydrological cycle and climate.
The gravitationally curved trajectory of an object around a point in space.
The lifting of an air mass as it flows over a mountain range.
Speeds of more than five times the speed of sound (Mach 5).
Having or representing the earth as the center, as in former astronomical systems.
A type of cyclone that occurs outside the tropics, often associated with fronts.
The instruments that are accommodated on a spacecraft.
An orbit around Earth of a satellite with an orbital period that matches Earth's rotation on its axis.
Minor corrections to the Keplerian model of a satellite orbit as an ellipse of constant shape and orientation.
Between the stars.
The force of attraction between all masses in the universe.
Water held underground in the soil or in pores and crevices in rock.
A wind that carries high-density air from a higher elevation down a slope under the force of gravity.
A type of instability that occurs when there is a velocity difference across the interface between two fluids.
Unusually cold sea surface temperatures across the east-central Equatorial Pacific.
A condition in which natural precipitation becomes acidic after reacting with air pollutants.
An event thought to mark the beginning of our Universe, where all matter exploded from an infinitely compressed state.
A phenomenon stating that moving air will have a lower pressure than the still air around it.
To measure wind speed.
A small body of matter from outer space that becomes incandescent as it enters the Earth's atmosphere.
The current geological age, viewed as the period during which human activity has been the dominant influence on climate and the environment.
A pair of stars that appear close to each other in the sky as seen from Earth.
An object that orbits the sun but cannot clear its path around it, smaller than a planet.
The boundary between two different air masses.
Water vapor content in the air and communicates changes in humidity.
The uppermost layer of the atmosphere where gases can escape into space.
A subject of natural science concerned with the physical processes and properties of the Earth and its surrounding space environment.
A device that selectively passes desired frequencies while removing undesired ones.
The angle of the orbit plane to the central body's equator.
An imaginary line of longitude 180 degrees east or west of the prime meridian.
The matter that exists in the space between the star systems in a galaxy.
A disc or short cylinder fitting closely within a tube in which it moves up and down against a liquid or gas.
A line on a map connecting points having the same temperature.
A process that generates a liquid from a solid or gas, or generates a non-liquid phase that behaves like a fluid.
The maximum possible mass of a stable cold star, above which it must collapse into a black hole.
The galaxy that contains our Solar System.
A rotorcraft that uses a single rotating blade.
Typically caused by heavy rain.
The gradual boundary between the heliosphere and the interstellar gas outside our solar system.
The amount of energy that passes through a unit area per unit time in a specified direction.
The amount of water vapor in the air.
To convert potential energy into mechanical work.
All the waters on the Earth’s surface, such as lakes and seas.
Precipitation that occurs when moist air is lifted over a mountain range.
A loose collection of atoms moving around each other.
Of or from outside the Earth or its atmosphere.
Flares that accelerate mostly electrons, with some protons.
A multi-year surplus accumulation of snowfall resulting in a mass of ice at least 0.1 square kilometers in area that shows evidence of movement.
The trapping of heat in the Earth’s atmosphere by greenhouse gases, which warms the planet.
A fourth state of matter where electrons are pulled free from atoms and can move independently.
A large-scale atmospheric convection cell in which air rises at the equator and sinks at medium latitudes.
The change in frequency or wavelength of a wave for an observer moving relative to its source.
The velocity of objects.
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.
One celestial body obscures another.
A giant cloud of dust and gas in space, some of which are regions where new stars are being born.
A half of the earth, usually divided into northern and southern halves by the equator.
All different kinds of light and energy in the universe.
The instantaneous variation of the frequency of a carrier wave in response to changes in the amplitude of a modulating signal.
The plane of Earth's equator passes through the center of the Sun's disk.
The change from a liquid to a vapor or gas form.
Part of the electromagnetic spectrum, also called gamma radiation, with high energy from events like solar flares and exploding stars.
A satellite instrument that measures and maps the Earth and its atmosphere.
Magnetic storms on Earth.
The time required for a satellite to make one complete orbit.
The breaking down of a chemical compound by photons.
An open-ended right-angled tube used to measure pressure in fluid flow.
A device consisting of a wheel or disc mounted to spin rapidly about an axis that can alter direction.
A brief epoch in the early universe, just after the Big Bang, during which the universe underwent rapid expansion.
An orbit where a satellite moves at the same rate as the Earth’s rotation, staying over the same spot.
Part of the electromagnetic spectrum that we cannot see but can feel as heat.
Global Positioning System, a system that uses satellites, ground stations, and receivers to determine location on Earth.
The lowest layer of the sun's atmosphere.
A line on a map connecting points having the same atmospheric pressure.
A circle of white or colored light around the sun, moon, or other luminous body caused by refraction through ice crystals.
The nozzle and valve through which fuel is sprayed into a combustion chamber.
The energy above which the electromagnetic force, weak force, and strong force become indistinguishable.
Gases in the atmosphere that trap heat from the sun, including carbon dioxide, methane, water vapor, and nitrous oxide.
A fast flowing, narrow air current found in the atmospheres of some planets, including Earth.
The process by which an atom or a molecule acquires a charge by gaining or losing electrons.
A method of propulsion that uses the reaction force of a high-speed jet of fluid expelled from a rocket engine.
The layer of the earth's atmosphere which contains a high concentration of ions and free electrons.
The area or region where a particular type of plant or animal lives and grows.
Precipitation composed of balls or irregular lumps of ice, produced in cumulonimbus clouds.
