An instrument for measuring atmospheric pressure.
A tide just after the first or third quarters of the moon when there is least difference between high and low water.
When a celestial body passes in front of a more distant star or object, obscuring it from sight.
The weather in some location averaged over a period of time.
A region of space having a gravitational field so intense that no matter or radiation can escape.
Bright glows and bands of light that appear in the skies at night near the South Pole, also known as the southern lights.
The smallest unit of a substance that still acts like the main substance, which can be a single atom or a group of atoms.
Taking place along constant streamlines, without turbulence.
A type of stellar remnant that can result from the gravitational collapse of a massive star after a supernova, made mostly of neutrons.
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.
A dry, warm, down-slope wind that occurs in the lee of a mountain range.
Related to the Moon.
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.
An instance of one moving object or person striking violently against another.
A celestial object consisting of a nucleus of ice and dust, and when near the sun, a 'tail' of gas and dust particles pointing away from the sun.
The study of the interactions between the hydrological cycle and climate.
The apparent shift in position of a nearby star against the background of distant objects due to Earth’s orbit around the Sun.
The balance between the gravitational force and the pressure gradient force in a fluid.
The vertical transfer of heat or other atmospheric properties.
The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.
The ongoing rise in global average temperature near the Earth’s surface.
The study of the chemical processes and substances that occur in biological and geological contexts.
A rotorcraft that uses a single rotating blade.
A nocturnal coastal breeze that blows from land to sea, caused by pressure differences due to temperature variations.
A sudden and severe flood, typically caused by heavy rain.
The part of the Earth consisting of the crust and mantle.
The atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form.
The study of climate, its variations, and impacts over long periods.
The leading edge of a cooler mass of air, replacing a warmer mass of air.
A radar tracking system that measures the velocity of objects.
For a solid object moving through a fluid or gas, drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid flow. It acts to oppose the motion of the object.
All the waters on the Earth’s surface, such as lakes and seas.
An instrument that measures water vapor content in the air and communicates changes in humidity visibly and immediately through a graph or a dial.
The point in an orbit where an object is closest to the Earth.
A small body of matter from outer space that enters the Earth’s atmosphere, becoming incandescent due to friction.
A satellite orbiting the Earth at the same rotational speed, appearing stationary relative to the surface.
A process in which no heat is transferred to or from the system by its surroundings.
A unit or 'particle' of electromagnetic energy, or light.
The basic building block of matter, made of protons, neutrons, and electrons. Different kinds of atoms exist, such as hydrogen and carbon.
The process of capturing and storing atmospheric carbon dioxide.
A detachable self-contained unit of a spacecraft.
The second of the three main layers in the Sun’s atmosphere, situated above the photosphere and below the corona.
A device designed to control the direction or characteristics of a fluid flow as it exits or enters an enclosed chamber.
The angular distance from the Greenwich meridian (0 degrees), along the equator.
Precipitation that occurs when moist air is lifted over a mountain range.
The change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source.
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope.
The measure of a celestial object’s intrinsic brightness as it would appear at a standard distance of 10 parsecs.
Change of a substance to a denser form, such as gas to a liquid.
A vortex of air within a convective storm.
Relating to speeds of more than five times the speed of sound (Mach 5).
Relating to the universe or cosmos, especially as distinct from the earth.
An adhesive is a substance added to two components in order to bond them together.
The rate at which the temperature of an air parcel changes as it moves vertically.
The scientific study of the atmosphere and weather patterns.
A brief epoch in the early universe, just after the Big Bang, during which the universe underwent an extremely rapid and exponential expansion.
An aileron is the hinged portion of a wing which is designed to impart roll to the aircraft.
An airfoil is the streamlined shape given to fins or wings for maximum aerodynamic efficiency in flight.
A force that pulls matter together.
Between the stars.
The remains of something that has been destroyed.
The gases held by gravity around Earth and around other planets. 'Atmosphere' can also be used to talk about gases around stars.
A unit of distance equal to exactly 1.852 kilometers or about 6076.1 feet.
A wall or partition designed to inhibit or prevent the spread of fire.
A process that generates a liquid from a solid or gas, or generates a non-liquid phase that behaves according to fluid dynamics.
A type of aircraft which derives both lift and propulsion from one or more sets of horizontally revolving overhead rotors, capable of moving vertically and horizontally.
A diffuser is a device for reducing the velocity and increasing the static pressure of a fluid passing through a system.
The pattern of temperature change over the course of a day.
Water condensation occurring on surfaces below freezing. Condensing water turns to ice.
The erosive process that reduces the size of glaciers.
A cloth canopy which fills with air and allows a person or heavy object to descend slowly when dropped from an aircraft.
Any communications link between an earth station and a satellite.
A hypergolic propellant combination used in a rocket engine is one whose components spontaneously ignite when they come into contact with each other.
A mechanical device for moving or controlling something.
A satellite instrument that measures and maps the Earth and its atmosphere, converting data into pictures.
An orbit where a satellite moves at the same rate as the Earth’s rotation, staying over the same spot.
The horizontal transfer of heat or other atmospheric properties.
Electromagnetic radiation with wavelengths between about 1000 micrometers and one meter, part of the electromagnetic spectrum.
Global Positioning System, a system that uses satellites, ground stations, and receivers to tell you exactly where you are on Earth.
A vehicle whose blades rotate in a horizontal plane due to aerodynamic forces alone, creating lift.
A type of star that pulsates radially, varying in both diameter and temperature, producing changes in brightness with a well-defined stable period and amplitude.
A region of the Solar System beyond the orbit of Neptune, believed to contain many small icy bodies.
A giant cloud of dust and gas in space, some of which are regions where new stars are being born.
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.
A model of the solar system where the Sun is at the center, as opposed to the Earth.
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 process of burning something.
The study of past climates using evidence from tree rings, ice cores, and other sources.
Part of the electromagnetic spectrum, also called gamma radiation. These waves have lots of energy and come from big events like solar flares and exploding stars.
The amount of matter something is made of.
A group of stars in the sky, often named after an animal, object, or person, forming certain patterns based on the observer's location.
The phenomenon when one celestial body obscures another.
A weather condition that sometimes occurs in the Pacific Ocean, affecting weather all over the world, starting with unusually warm water in the Pacific Ocean near the equator.
The breaking down of a chemical compound by photons.
The climate of a very small or restricted area, especially when it differs from the surrounding climate.
A moveable surface on the horizontal stabilizer of an aircraft responsible for pitch control.
Relating to or involving the branch of physics that deals with the production and effects of very low temperatures.
Solar radiation incident upon a unit horizontal surface on or above the Earth's surface.
The study of objects moving through the air that have been given a short-lived acceleration.
A natural object that travels around a bigger natural object, such as a planet or dwarf planet.
The distance north or south of the equator, measured in degrees.
A sudden electrostatic discharge during a thunderstorm, accompanied by a vivid flash of light.
A spherical shell around our solar system that may contain more than a trillion icy bodies.
An imaginary gigantic flat plate containing an Earth satellite's orbit.
An event that occurs when the Earth passes between the Sun and the Moon, causing the Earth’s shadow to fall on the Moon.
The boundary between two different air masses.
The main body of an aircraft.
The pathways through which water is cycled in the terrestrial biosphere.
The third planet of the solar system which is the only known life habitable planet in the universe.
A condition in which natural precipitation becomes acidic after reacting with air pollutants.
The deflection of moving objects when they are viewed in a rotating reference frame.
A glacial period characterized by lower global temperatures and ice sheet expansion.
A quantity measuring the influence of a substance on the magnetic flux in the region it occupies.
Minor corrections to the Keplerian model of a satellite orbit as an ellipse of constant shape and orientation.
A force acting briefly on a body and producing a finite change of momentum.
Aerodynamics is the study of the motion and forces of gases moving around solid objects.
The galaxy that contains our Solar System.
A large body in outer space that circles around the sun or another star.
Change from a liquid (more dense) to a vapor or gas (less dense) form.
Natural light displays in the Earth’s sky, typically seen in high-latitude regions.
The branch of geology that focuses on the age and time sequence of rock layers.
Production of light when electricity flows through a tube that is filled with a type of gas.
The gravitationally curved trajectory of an object around a point in space.
The gradual boundary between the heliosphere and the interstellar gas outside our solar system.
The instantaneous variation of the frequency of a carrier wave in response to changes in the amplitude of a modulating signal.
The observation that the farther away a galaxy is, the faster it is moving away from us.
A movement or series of moves requiring skill and care.
The region of the Earth's interior between the crust and the core, consisting of hot, dense silicate rocks.
Any reciprocating or rotating device that compresses a gas.
The stuff that everything is made of, including atoms and larger structures like planets.
The outer atmosphere of a star.
Technology used to improve the performance of optical systems by reducing the effect of wavefront distortions.
A crater on a planet or satellite caused by the impact of a meteorite or other object.
Specific information used to define and locate a particular satellite.
The lowest layer of the sun's atmosphere.
Part of the electromagnetic spectrum that we cannot see with our eyes but can feel as heat, made of waves released by hot objects.
A device that converts potential energy into mechanical work.
A theory which unifies the electromagnetic, strong, and weak forces.
A device that measures altitude.
The idea that two identical spin-1/2 particles cannot have both the same position and the same velocity.
The geological process in which sediments, soil, and rocks are added to a landform or land mass.
The measure of how wide an object appears in the sky, expressed in degrees, arcminutes, and arcseconds.
Astronomy is the study of everything that lies beyond the Earth's atmosphere.
An extremely light (possibly massless) particle that is affected only by the weak force and gravity.
An area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.
The circular orbit at approximately 35,800 km above the equator, where satellites travel at the same speed as the Earth's rotation, appearing stationary to an observer on Earth.
Long-term changes in temperature, precipitation, wind patterns, and other aspects of the Earth’s climate system.
Inclination of an aircraft's wing from the horizontal, especially upwards away from the fuselage.
The international unit of frequency equal to one cycle per second.
The amount of water vapor in the air.
Objects that are round and orbit the sun, but unlike planets, dwarf planets are not able to clear their path around the sun.
A tiny amount or small piece of something.
A measure of how an orbit deviates from being circular, describing the shape of an orbit.
The atmospheric layer above the stratosphere, extending from about 50 to 85 kilometers altitude.
Organisms interacting with their physical environment.
The thermal radiation left over from the time of recombination in Big Bang cosmology.
High-energy radiation, mainly originating outside the Solar System and even from distant galaxies.
A wind that results from a balance between the Coriolis force and the pressure gradient force.
The angle at which an antenna must be pointed above the horizon for optimal reception from a spacecraft.
A disc or short cylinder fitting closely within a tube in which it moves up and down against a liquid or gas.
The frozen water part of the Earth system, including glaciers and sea ice, affecting climate and weather.
A two-axis mount for supporting and rotating an instrument in both vertical (altitude) and horizontal (azimuth) directions.
The trapping of heat in the Earth’s atmosphere by greenhouse gases, which warms the planet.
Ground stations are the link between the control system and a satellite in orbit, tracking a satellite's signal to find its location and the status of equipment onboard.
A large-scale atmospheric convection cell in which air rises at the equator and sinks at medium latitudes.
Aphelion is the point in an object's orbit where it is farthest from the Sun.
Bright glows and bands of light that appear in the skies at night near the North Pole, also known as the northern lights.
An event thought to mark the beginning of our Universe, postulating that all matter exploded from an infinitely compressed state 10 to 20 billion years ago.
A synthetic fibre of high tensile strength used especially as a reinforcing agent in the manufacture of tyres and other rubber products.
A family of compounds of chlorine, fluorine, and carbon, entirely of industrial origin. CFC's are responsible for Ozone layer deprivation.
The distance light travels in one year, approximately 9.46 trillion kilometers.
The region between Earth and the Moon.
The inability to receive a satellite signal because the satellite's orbital path has taken it below the antenna's horizon.
The lifting of an air mass as it flows over a mountain range.
One component of fuel used to support the combustion of a rocket propellant.
A layer in the Earth’s stratosphere that absorbs most of the Sun’s harmful ultraviolet radiation.
A tropical cyclone with sustained winds of at least 74 mph, particularly a storm in the Caribbean.
A material in which two or more distinct, structurally complementary materials are combined to produce structural or functional properties not present in any individual component.
A highly energetic explosion observed in distant galaxies, thought to be associated with the collapse of massive stars or the merger of neutron stars.
The instruments that are accommodated on a spacecraft.
A surface of constant gravitational potential around the Earth - an averaged surface perpendicular to the force of gravity.
The luminous flux per unit area on an intercepting surface at any given point.
A meteoroid that lands on the surface of a planet.
The science of the origin and development of the universe, dominated by the Big Bang theory.
Impulsive flares accelerate mostly electrons, with some protons.
The process of converting a substance into fine particles or droplets suspended in the air.
An open-ended right-angled tube pointing in opposition to the flow of a fluid and used to measure pressure.
The nozzle and valve through which fuel is sprayed into a combustion chamber.
A domed building in which images of stars, planets, and constellations are projected for public entertainment or education.
The force of attraction between all masses in the universe.
Process by which significant changes in the chemistry of Earth's atmosphere may enhance the natural process that warms our planet and elevates temperatures.
A celestial object that is too large to be a planet but too small to sustain hydrogen fusion reactions in its core, which is the defining characteristic of stars.
The opposite of El Niño, occurring due to unusually cold sea surface temperatures across the east-central Equatorial Pacific, affecting winter temperatures in the Southeast and Northwest United States.
The short dimension (front-to-rear) of a glider's wing.
Intermittent burning of a rocket motor, accompanied by the sound of a steam engine starting.
The amount of energy that passes through a unit area per unit time in a specified direction.
A thick cloud of tiny water droplets suspended in the atmosphere near the Earth’s surface.
Number of cycles and parts of cycles completed per second. F = 1/T, where T is the length of one cycle in seconds.
A disturbance in the magnetosphere due to solar activity.
The region surrounding a celestial body where its magnetic field controls the motions of charged particles.
An artificial satellite used to relay radio, television, and telephone signals around the earth, usually in geostationary orbit.
Relating to or found in the sea.
The process by which one substance takes in or absorbs another.
Having or representing the earth as the centre, as in former astronomical systems.
A compact region at the center of a galaxy that has a much higher than normal luminosity.
Rock that has undergone transformation by heat, pressure, or other natural agencies.
The physical elements of the Earth's surface, crust, and interior.
The force that can alter the motion of electricity, measured in terms of the energy per unit charge imparted to electricity passing through the source of this force.
A large, bowl-shaped dent in the ground, caused by an explosion or the impact of a meteorite.
The angle of the orbit plane to the central body's equator.
A fourth state of matter -- not a solid, liquid or gas, where electrons are pulled free from the atoms and can move independently.
The angular distance of an object above the horizon.
The scientific method of dating tree rings to the exact year they were formed.
A line on a map connecting points having the same atmospheric pressure at a given time or on average over a given period.
Downward inclination of an aircraft's wing.
A weather system with high atmospheric pressure at its center.
An astronaut is someone who travels in space.
A type of instability that occurs when there is a velocity difference across the interface between two fluids.
A seasonal prevailing wind that brings heavy rains.
A position in space where the gravitational forces of a two-body system, like Earth and the Moon, produce enhanced regions of attraction and repulsion.
The force that directly opposes the weight of an airplane and holds the airplane in the air.
High-altitude clouds made of ice crystals, appearing thin and wispy.
A descent during air travel is any portion where an aircraft decreases altitude, and is the opposite of an ascent or climb.
A galaxy cluster, or cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity.
An almost colorless, gaseous form of oxygen with an odor similar to weak chlorine.
The study of the history of the oceans in the geological past.
A massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter.
The lowest possible temperature, at which substances contain no heat energy.
A loose collection of atoms moving around each other.
The shadow cast by the earth or moon over an area experiencing a partial eclipse.
The plane of Earth’s orbit around the Sun, which is used as the primary reference plane for celestial coordinates.
Time required for a satellite to make one complete orbit.
The universe seen as an orderly, harmonious whole.
A multi-year surplus accumulation of snowfall in excess of snowmelt on land and resulting in a mass of ice at least 0.1 square kilometers in area that shows some evidence of movement in response to gravity.
Level flight after an aircraft climbs to a set altitude and before it begins to descend.
The moment in which the plane of Earth's equator passes through the center of the Sun's disk, occurring twice each year.
An area of low pressure where winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
A region near the equator where the trade winds of the Northern and Southern Hemispheres come together.
Relating to planets located outside our solar system.
An instrument used to measure wind speed.
A type of cyclone that occurs outside the tropics, often associated with fronts.
Apogee is the point in an orbit where an object is farthest from the Earth.
Free drift mode refers to a state of motion engaged by an object in orbit, whereby constant attitude is not maintained.
The space around a magnet where the magnetic force is active, helping protect Earth from space weather.
The study of the magnetic properties and behavior of electrically conducting fluids.
The increase in signal power produced by an amplifier.
A prolonged period of abnormally low rainfall.
A structure formed by diffused material in orbital motion around a massive central body.
The upper boundary of the mesosphere where the temperature of the atmosphere reaches its lowest point.
A magnetic storm on Earth.
The name for all the different kinds of light and energy in the universe, including radio waves, microwaves, infrared radiation, visible light, ultraviolet light, X-rays, and gamma rays.
A little chunk of rock in space smaller than a pickup truck.
A geosynchronous orbit (sometimes abbreviated GSO) is an orbit around Earth of a satellite with an orbital period that matches Earth's rotation on its axis, which takes one sidereal day.
The phenomenon that produces a network of fine cracks on the surface of a material.
A self-propelled precision-guided munition system.
A type of cloud associated with thunderstorms and heavy precipitation.
A technique used to determine the properties of waves by analyzing the patterns created when they overlap.
The wearing or burning away of the throat of the motor nozzle caused by the hot gases ejecting from the motor.
Gases in the atmosphere that trap heat from the sun, such as carbon dioxide, methane, water vapor, and nitrous oxide.
Transmission of a continuously variable signal as opposed to a discretely variable signal.
A method of propulsion that uses the reaction force of a high-speed jet of fluid expelled from a rocket engine.
The angular distance of an Earth satellite (or planet) from its perigee (or perihelion) as seen from the center of the Earth (sun).
Geophysics is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis.
The branch of physics that deals with the interaction between electric charges and currents, and magnetic fields.
The measurement of light intensity, often used in the study of stars and other celestial objects.
Bodies in space orbit in elliptical rather than circular orbits because of factors such as gravity and drag.
The complex of physical, chemical, and biological factors in which a living organism or community exists.
An imaginary line of longitude 180 degrees east or west of the prime meridian.
An asterism is a recognizable pattern or group of stars that is not an official constellation.
The layer of the earth's atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio waves.
Precipitation composed of balls or irregular lumps of ice, produced when large frozen raindrops in cumulonimbus clouds act as embryos that grow by accumulating supercooled liquid droplets.
A wind that carries high-density air from a higher elevation down a slope under the force of gravity.
A device that selectively passes desired frequencies while removing undesired ones.
The process of life arising naturally from non-living matter in the universe.
A large body of air with uniform temperature and humidity characteristics.
The measure of the reflectivity of a surface or body, usually expressed as a percentage.
Fluffy, white clouds with a flat base, typically indicating fair weather.
Between the planets in our solar system.
A type of matter hypothesized to account for a large part of the total mass in the universe, not directly observable by emitted radiation.
Water held underground in the soil or in pores and crevices in rock.
The area or region where a particular type of plant or animal lives and grows.
Of or from outside the earth or its atmosphere.
The apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability.
The universe’s laws and constants are fine-tuned in such a way that they allow for the existence of life, specifically human life.
The study of the origin, evolution, and possibility of life in the universe.
The energy above which, it is believed, the electro-magnetic force, weak force, and strong force become indistinguishable from each other.
The development or strengthening of cyclonic circulation in the atmosphere.
A type of mid-level cloud that covers the sky with a gray or blue-gray sheet.
The process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons.
A spiral galaxy approximately 2.5 million light-years away from Earth, located in the constellation Andromeda.
A fast flowing, narrow air current found in the atmospheres of some planets, including Earth.
A type of solar eclipse where the moon covers the center of the sun, leaving a ring-like appearance.
Resulting from the influence of human beings on nature.
The circle around a planet or moon that is the same distance from its north pole and its south pole.
A point of a crescent, especially of the moon which indicates the meeting of two curves.
A type of mid-level cloud characterized by white or gray patches.
Outside the Milky Way Galaxy.
Rocks floating around in space. Some are the size of a pick-up truck. Others are hundreds of miles across.
The distance from the Earth to the sun. On average, the sun is 149,599,000 kilometers, or 93,440,974 miles from Earth.
The matter that exists in the space between the star systems in a galaxy.
A planet that orbits a star outside our solar system.
The uppermost layer of the atmosphere, where atmospheric gases can escape into outer space.
A circle of white or coloured light around the sun, moon, or other luminous body caused by refraction through ice crystals in the atmosphere.
The current geological age, viewed as the period during which human activity has been the dominant influence on climate and the environment.
The branch of science that deals with the possibility and likely nature of life on other planets or in space.
Without oxygen; anaerobic bacteria are bacteria that live without oxygen.
The increase in the volume of fuel on combustion in the cylinder of an engine.
Each type of matter particle has a corresponding antiparticle. When a particle collides with its antiparticle, they annihilate, leaving only energy.
A scientific observer of the celestial bodies.
A device consisting of a wheel or disc mounted so that it can spin rapidly about an axis which is itself free to alter in direction.
A line on a map connecting points having the same temperature at a given time or on average over a given period.
The property of being directionally dependent, as opposed to isotropy, which implies identical properties in all directions.
A wire or set of wires used to send and receive electromagnetic waves.
