Space Glossary: Space Concept Builder PDF

World Space Week 2024 Space Education Research Lab National Center of GIS and Space Application...

World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 13. Space Glossary: Space Concept Builder S.NO Term Definition 1 Ablation The erosive process that reduces the size of glaciers Absolute 2 The measure of a celestial object’s intrinsic brightness as it would appear at a standard distance of 10 parsecs. Magnitude 3 Absolute zero The lowest possible temperature, at which substances contain no heat energy 4 Absorption The process by which one substance takes in or absorbs another. 5 Accretion Disk A structure formed by diffused material in orbital motion around a massive central body. 6 Acid rain A condition in which natural precipitation becomes acidic after reacting with air pollutants. Active Galactic 7 A compact region at the center of a galaxy that has a much higher than normal luminosity. Nucleus (AGN) 8 Actuator A mechanical device for moving or controlling something. 9 Adaptive Optics Technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. 10 Adhesive An adhesive is a substance added to two components in order to bond them together. Adiabatic Lapse 11 The rate at which the temperature of an air parcel changes as it moves vertically. Rate 12 Adiabatic Process A process in which no heat is transferred to or from the system by its surroundings. 13 Advection The horizontal transfer of heat or other atmospheric properties. 14 Aerodynamics Aerodynamics is the study of the motion and forces of gases moving around solid objects. 15 Aerosolization The process of converting a substance into fine particles or droplets suspended in the air. 16 Aileron An ailerons is the hinged portion of a wing which is designed to impart roll to the aircraft. 17 Air Mass A large body of air with uniform temperature and humidity characteristics. 18 Airfoil An airfoil is the streamlined shape given to fins or wings for maximum aerodynamic efficiency in flight. 19 Albedo The measure of the reflectivity of a surface or body, usually expressed as a percentage. 20 Altazimuth Mount A two-axis mount for supporting and rotating an instrument in both vertical (altitude) and horizontal (azimuth) directions. 21 Altimeter A device that measures altitude. 22 Altitude The angular distance of an object above the horizon. 23 Altocumulus A type of mid-level cloud characterized by white or gray patches. 24 Altostratus A type of mid-level cloud that covers the sky with a gray or blue-gray sheet. 25 An asterism An asterism is a recognizable pattern or group of stars that is not an official constellation. 26 Anaerobic Without oxygen; anaerobic bacteria are bacteria that live without oxygen. 27 Analog Transmission of a continuously variable signal as opposed to a discretely variable signal. 28 Andromeda Galaxy A spiral galaxy approximately 2.5 million light-years away from Earth, located in the constellation Andromeda. 29 Anemometer An instrument used to measure wind speed. 30 Angular size is the measure of how wide an object appears in the sky, expressed in degrees, arcminutes, and arcseconds. 31 Anhedral Downward inclination of an aircraft's wing. 32 Anisotropy The property of being directionally dependent, as opposed to isotropy, which implies identical properties in all directions. 33 Annular Eclipse A type of solar eclipse where the moon covers the center of the sun, leaving a ring-like appearance. 34 Anomaly The angular distance of an Earth satellite (or planet) from its perigee (or perihelion) as seen from the center of the Earth (sun). 35 Antenna A wire or set of wires used to send and receive electromagnetic waves. The universe’s laws and constants are fine-tuned in such a way that they allow for the existence of life, specifically human life. 36 Anthropic principle We see the universe the way it is because if it were different we would not be here to observe it. The current geological age, viewed as the period during which human activity has been the dominant influence on climate 37 Anthropocene and the environment. 38 Anthropogenic Resulting from the influence of human beings on nature. 39 Anticyclone A weather system with high atmospheric pressure at its center. Each type of matter particle has a corresponding antiparticle. When a particle collides with its antiparticle, they annihilate, 40 Antiparticle leaving only energy. 41 Aphelion Aphelion is the point in an object's orbit where it is farthest from the Sun. 42 Apogee Apogee is the point in an orbit where an object is farthest from the Earth. 43 Asteroid Rocks floating around in space. Some are the size of a pick-up truck. Others are hundreds of miles across. 44 Astrobiogenesis The process of life arising naturally from non-living matter in the universe. 45 Astrobiology The study of the origin, evolution, and possibility of life in the universe. 46 Astronaut An astronaut is someone who travels in space. 47 Astronomer A scientific observer of the celestial bodies. 1 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad Astronomical Unit 48 The distance from the Earth to the sun. On average, the sun is 149,599,000 kilometers, or 93,440,974 miles from Earth. (AU) 49 Astronomy Astronomy is the study of everything that lies beyond the Earth's atmosphere. The gases held by gravity around Earth and around other planets. "Atmosphere" can also be used to talk about gases around 50 Atmosphere stars. The basic building block of matter. It is made of protons, neutrons, and electrons. There are many different kinds of atoms. For 51 Atom example, the simplest atom with one proton and one electron is a hydrogen atom. An atom with six protons, six neutrons, and six electrons is a carbon atom 52 Attitude The position and orientation of an object relative to a fixed line, plane of axes or reference. 53 Aurora Natural light displays in the Earth’s sky, typically seen in high-latitude regions. 54 Aurora australis Bright glows and bands of light that appear in the skies at night near the South Pole. They are also called the southern lights. 55 Aurora borealis Bright glows and bands of light that appear in the skies at night near the North Pole. They are also called the northern lights. 56 Autogyro A vehicle whose blades rotate in a horizontal plane due to aerodynamic forces alone, creating lift. 57 Avalanche A large mass of material falling or sliding rapidly due to the force of gravity. 58 Aviation The flying or operating of aircraft. 59 Azimuth The horizontal angle or direction of a compass bearing. 60 Ballistics Study of objects moving through the air that have been given a short lived acceleration. Baroclinic 61 A type of instability in the atmosphere that can lead to the development of cyclones. Instability 62 Baroclinicity The state of stratification in a fluid in which surfaces of constant pressure intersect surfaces of constant density. 63 Barometer An instrument for measuring atmospheric pressure. 64 Barycenter The common center of mass around which two or more bodies revolve. 65 Basin A low area of the Earth's crust of tectonic origin, commonly filled with sediment. A phenomenon first described by the 18th century Swiss scientist Daniel Bernoulli who studied the pressures in moving fluid 66 Bernoulli Effect streams.The effect states that moving air will have a lower pressure than the still air around it. An event thought to mark the beginning of our Universe. The big bang theory postulates that 10 to 20 billion years ago, all 67 Big Bang matter exploded from an infinitely compressed state. 68 Binder A material which binds the constituent elements of a composite propellant into a solid 69 Biogeochemistry The study of the chemical processes and substances that occur in biological and geological contexts. Part of the Earth system in which life can exist, between the outer portion of the geosphere and the inner portion of the 70 Biosphere atmosphere. 71 Black Hole A region of space having a gravitational field so intense that no matter or radiation can escape. 72 Blade Long thin wing, rotated around a central hub, such as on a propeller. 73 Blizzard A severe snowstorm with strong winds and low visibility. 74 Blue stars These are the hottest stars, with a surface temperature of more than 37,000°F. An instrument for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature- 75 Bolometer dependent electrical resistance. 76 Booster The additional engine added to a rocket to give it extra thrust in first phase of flight. 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 77 Brown Dwarf defining characteristic of stars. 78 Buckle A bend or kink formed by overstressing the airframe. 79 Buffeting Repeated forces experienced by a model due to disturbed unsteady airflow. 80 Bypass ratio A ratio between cold airflow and hot airflow in turbofan engine. 81 Calibrate mark (a gauge or instrument) with a standard scale of readings. 82 Camber The increase in curvature of an airfoil along its chord. 83 Canard A fin or wing located at the middle or front of a rocket. 84 Canopy The fabric of the top of a parachute. 85 Cantilever A projecting member, fixed at one end rigidly and free at the other. 86 Carbon Footprint The total amount of greenhouse gases emitted by an individual, organization, event, or product. Carbon 87 The process of capturing and storing atmospheric carbon dioxide. Sequestration The attractive pressure between two flat, parallel metal plates placed very near to each other in a vacuum. The pressure is due 88 Casimir effect to a reduction in the usual number of virtual particles in the space between the plates. 89 Celestial Body a natural object visible in the sky. 90 Centrifugal Force An apparent force that acts outward on a body moving around a center, arising from the body’s inertia. A type of star that pulsates radially, varying in both diameter and temperature, and producing changes in brightness with a 91 Cepheid Variable well-defined stable period and amplitude. Chandrasekhar 92 The maximum possible mass of a stable cold star, above which it must collapse into a black hole. limit A band of radio frequencies assigned for a particular purpose, usually for the establishment of one complete communication 93 Channel link, or a path for an electrical signal 2 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 94 Chlorofluorocarbon A compound consisting of chlorine, fluorine, and carbon, used in refrigerants and aerosol propellants. Chlorofluorocarbon A family of compounds of chlorine, fluorine, and carbon, entirely of industrial origin. CFC's are responsible for Ozone layer 95 (CFC) deprivation. 96 Chord The short dimension (front-to-rear) of a glider's wing. 97 Chromosphere The second of the three main layers in the Sun’s atmosphere, situated above the photosphere and below the corona. 98 Chronostratigraphy The branch of geology that focuses on the age and time sequence of rock layers. 99 Chuffing Intermittent burning of a rocket motor, accompanied by the sound of a steam engine starting. 100 Cirrus High-altitude clouds made of ice crystals, appearing thin and wispy. 101 Cislunar Between earth and moon The circular orbit at approximately 35,800 km above the equator, 102 Clarke Belt where the satellites travel at the same speed as the earth's rotation (Geostationary Orbit) and thus appear to be stationary to an observer on Earth. 103 Climate The weather in some location averaged over a period of time. 104 Climate Change Long-term changes in temperature, precipitation, wind patterns, and other aspects of the Earth’s climate system. 105 Climatology The study of climate, its variations, and impacts over long periods. A galaxy cluster, or cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are 106 Cluster bound together by gravity 107 Cold Front The leading edge of a cooler mass of air, replacing a warmer mass of air. 108 Collision An instance of one moving object or person striking violently against another. 109 Combustion The process of burning something. A celestial object consisting of a nucleus of ice and dust, and when near the sun, a “tail” of gas and dust particles pointing 110 Comet away from the sun. Communication 111 An artificial satellite used to relay radio, television, and telephone signals around the earth, usually in geostationary orbit Satellite A material in which two or more distinct, structurally complementary materials, usually a matrix material and a 112 Composite reinforcing material,are combined to produce structural or functional properties not present in any individual component. 113 Compressor Any reciprocating or rotating device that compresses a gas 114 Condensation Change of a substance to a denser form, such as gas to a liquid A group of stars in the sky. They're often named after an animal, object, or person. The stars form certain patterns based on 115 Constellation where you are. We have one view of stars here on Earth, but from another solar system or galaxy, the constellations would look different. 116 Convection The vertical transfer of heat or other atmospheric properties. 117 Coriolis The apparent deflection of moving objects from a straight path when viewed from a rotating frame of reference 118 Coriolis Effect The deflection of moving objects when they are viewed in a rotating reference frame. 119 Corona The outer atmosphere of a star. 120 Cosmic Relating to the universe or cosmos, especially as distinct from the earth. Cosmic Microwave 121 The thermal radiation left over from the time of recombination in Big Bang cosmology. Background (CMB) 122 Cosmic Ray High-energy radiation, mainly originating outside the Solar System and even from distant galaxies. The science of the origin and development of the universe. Modern cosmology is dominated by the Big Bang theory, which 123 Cosmology brings together observational astronomy and particle physics. 124 Cosmos The universe seen as an orderly, harmonious whole. 125 Crater A large, bowl-shaped dent in the ground. They can be caused by an explosion or the impact of a meteorite. 126 Crazing Crazing is the phenomenon that produces a network of fine cracks on the surface of a material 127 Cruise Cruise is level flight after an aircraft climbs to a set altitude and before it begins to descend. 128 Cryogenic Relating to or involving the branch of physics that deals with the production and effects of very low temperatures. 129 Cryosphere The frozen water part of the Earth system, including glaciers and sea ice, affecting climate and weather. 130 Cumulonimbus A type of cloud associated with thunderstorms and heavy precipitation. 131 Cumulus Fluffy, white clouds with a flat base, typically indicating fair weather. 132 Cusp A point of a crescent, especially of the moon which indicates meeting of two curves. 133 Cyclogenesis The development or strengthening of cyclonic circulation in the atmosphere. An area of low pressure where winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern 134 Cyclone Hemisphere. A type of matter hypothesized to account for a large part of the total mass in the universe, not directly observable by emitted 135 Dark Matter radiation. 3 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 136 Debris The remains of something that has been destroyed 137 Dendrochronology The scientific method of dating tree rings to the exact year they were formed. 138 Deposition Deposition is the geological process in which sediments, soil and rocks are added to a landform or land mass. 139 Descent A descent during air travel is any portion where an aircraft decreases altitude, and is the opposite of an ascent or climb. The atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense 140 Dew point and dew can form. 141 Diffuser A diffuser is a device for reducing the velocity and increasing the static pressure of a fluid passing through a system. 142 Dihedral Inclination of an aircraft's wing from the horizontal, especially upwards away from the fuselage. 143 Diurnal Cycle The pattern of temperature change over the course of a day. The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave (or other periodic event) for an 144 Doppler observer moving relative to its source. 145 Doppler Effect The change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source. 146 Doppler Radar A radar tracking system that measures the velocity of objects. 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 147 Double Star from Earth when viewed through an optical telescope. For a solid object moving through a fluid or gas, drag is the sum of all the aerodynamic or hydrodynamic forces in the 148 Drag direction of the external fluid flow. It acts to oppose the motion of the object 149 Drought A prolonged period of abnormally low rainfall. Objects that are round and orbit the sun, just like planets do. But unlike planets, dwarf planets are not able to clear their path 150 Dwarf planet around the sun. That means there are other objects orbiting at roughly the same distance from the sun. A dwarf planet is much smaller than a planet (smaller even than Earth's moon), but it is not a moon. Pluto is the best known of the dwarf planets. 151 Earth The third planet of solar system which is the only known life habitable planet in universe. 152 Earth Space Link Any communications link between an earth station and a satellite 153 Eccentricity A measure of how an orbit deviates from being circular. One of six Keplerian elements, it describes the shape of an orbit. 154 Eclipse The phenomenon when one celestial body obscures another 155 Ecliptic The plane of Earth’s orbit around the Sun, which is used as the primary reference plane for celestial coordinates. 156 Ecosystem organisms interacting with their physical environment A weather condition that sometimes occurs in the Pacific Ocean. It is so big that it affects weather all over the world. It starts 157 El Niño with unusually warm water in the Pacific Ocean near the equator. A warming of the surface waters of the eastern equatorial Pacific that occurs at irregular intervals of 2-7 years, usually lasting 1-2 years. Electromagnetic The name for all the different kinds of light and energy in the universe. This includes radio waves, microwaves, infrared 158 Spectrum radiation, visible light, ultraviolet light, X-rays, and gamma rays. 159 Electromagnetism The branch of physics that deals with the interaction between electric charges and currents, and magnetic fields. The force that can alter the motion of electricity, measured in terms of the energy per unit charge imparted to electricity 160 Electromotive Force passing through the source of this force. Electromotive force causes current flow in a circuit. 161 Element Set Specific information used to define and locate a particular satellite. 162 Elevation The angle at which an antenna must be pointed above the horizon for optimal reception from a spacecraft. 163 Elevator moveable surface on the horizontal stabilizer of an aircraft. The surface is responsible for pitch control. 164 Elliptical Orbit Bodies in space orbit in elliptical rather than circular orbits because of factors such as gravity and drag. 165 Engine An engine is a device that converts potential energy into mechanical work. 166 Environment The complex of physical, chemical, and biological factors in which a living organism or community exists. 167 Equator The circle around a planet or moon that is the same distance from its north pole and its south pole. An equinox is the moment in which the plane of Earth's equator passes through the center of the Sun's disk, which occurs 168 Equinox twice each year, around 20 March and 23 September. The wearing or burning away of the throat of the motor nozzle caused by the hot gases ejecting from the motor. Also called 169 Erosion Ablation. 170 Evaporation Change from a liquid (more dense) to a vapor or gas (less dense) form. The idea that two identical spin-1/2 particles cannot have (within the limits set by the uncertainty principle) both the same 171 Exclusion principle position and the same velocity. 172 Exobiology the branch of science that deals with the possibility and likely nature of life on other planets or in space. 173 Exoplanet A planet that orbits a star outside our solar system. 174 Exoplanetary Relating to planets located outside our solar system. The uppermost layer of the atmosphere, its lower boundary is estimated at 500 km to 1000 km above the Earth's surface. It is 175 Exosphere only from the exosphere that atmospheric gases can, to any appreciable extent, escape into outer space. 4 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 176 Expansion the increase in the volume of fuel on combustion in the cylinder of an engine, or the piston stroke in which this occurs. 177 Extragalactic Outside Milky way Galaxy. 178 Extraterrestrial Of or from outside the earth or its atmosphere. Extratropical 179 A type of cyclone that occurs outside the tropics, often associated with fronts. Cyclone The apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their 180 Fermi Paradox probability. 181 Filter Device that while selectively passing desired frequencies removes undesired ones. 182 Firewall A wall or partition designed to inhibit or prevent the spread of fire. 183 Flash Flood A sudden and severe flood, typically caused by heavy rain. 184 Floodplain An area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding. 185 Fluorescent Production of light when electricity flows through a tube that is filled with a type of gas. 186 Flux The amount of energy that passes through a unit area per unit time in a specified direction. 187 Foehn Wind A dry, warm, down-slope wind that occurs in the lee of a mountain range. 188 Fog A thick cloud of tiny water droplets suspended in the atmosphere near the Earth’s surface. 189 Free Drift Free drift mode refers to a state of motion engaged by an object in orbit, whereby constant attitude is not maintained. 190 Frequency Number of cycles and parts of cycles completed per second. F = 1/T, where T is the length of one cycle in seconds. Frequency 191 The instantaneous variation of the frequency of a carrier wave in response to changes in the amplitude of a modulating signal. Modulation 192 Front The boundary between two different air masses. 193 Frost Water condensation occurring on surfaces below freezing. Condensing water turns to ice. 194 Fuselage The main body of an aircraft. 195 Gain The increase in signal power produced by an amplifier 196 Galaxy A massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter. Part of the electromagnetic spectrum, also called gamma radiation. These waves have lots of energy. They come from big 197 Gamma rays events like solar flares and exploding stars. Gamma-Ray Burst A highly energetic explosion observed in distant galaxies, thought to be associated with the collapse of massive stars or the 198 (GRB) merger of neutron stars. 199 Gas A loose collection of atoms moving around each other. 200 Geocentric Having or representing the earth as the centre, as in former astronomical systems. 201 Geoid A surface of constant gravitational potential around the Earth - an averaged surface perpendicular to the force of gravity. Geomagnetic 202 A magnetic storm on Earth. Storms Geophysics is a subject of natural science concerned with the physical processes and physical properties of the Earth and its 203 Geophysics surrounding space environment, and the use of quantitative methods for their analysis. 204 Geosphere The physical elements of the Earth's surface, crust, and interior. 205 Geostationary A satellite orbiting the Earth at the same rotational speed, appearing stationary relative to the surface. 206 Geostationary Orbit An orbit where a satellite moves at the same rate as the Earth’s rotation, staying over the same spot. 207 Geostrophic Wind A wind that results from a balance between the Coriolis force and the pressure gradient force. Geosynchronous A geosynchronous orbit (sometimes abbreviated GSO) is an orbit around Earth of a satellite with an orbital period that 208 orbit matches Earth's rotation on its axis, which takes one sidereal day (23 hours, 56 minutes, and 4 seconds). 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 209 Glacier kilometers in area that shows some evidence of movement in response to gravity. 210 Global Warming The ongoing rise in global average temperature near the Earth’s surface. This stands for Global Positioning System. It’s a system that uses satellites, ground stations, and receivers to tell you exactly 211 GPS where you are on Earth. Grand unification The energy above which, it is believed, the electro-magnetic force, weak force, and strong force become indistinguishable 212 energy from each other. Grand unified 213 A theory which unifies the electromagnetic, strong, and weak forces. theory (GUT) 214 Gravitational force The force of attraction between all masses in the universe 215 Gravity A force that pulls matter together. Process by which significant changes in the chemistry of Earths atmosphere may enhance the natural process that warms our 216 Greenhouse planet and elevates temperatures. 5 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 217 Greenhouse Effect The trapping of heat in the Earth’s atmosphere by greenhouse gases, which warms the planet. Gases in the atmosphere that trap heat from the sun. Some greenhouse gases are carbon dioxide, methane, water vapor, and 218 Greenhouse gas nitrous oxide. Ground stations are the link between the control system and a satellite in orbit. They track a satellite's signal to find it's 219 Ground Station location, and the status of equipment onboard and distribute that information to interested parties. 220 Groundwater Water held underground in the soil or in pores and crevices in rock. 221 Gyroscope 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. 222 Habitat The area or region where a particular type of plant or animal lives and grows. 223 Hadley Cell A large-scale atmospheric convection cell in which air rises at the equator and sinks at medium latitudes. Precipitation composed of balls or irregular lumps of ice. Hail is produced when large frozen raindrops, or almost any 224 Hail particles, in cumulonimbus clouds act as embryos that grow by accumulating supercooled liquid droplets. A circle of white or coloured light around the sun, moon, or other luminous body caused by refraction through ice crystals in 225 Halo the atmosphere. 226 Haze 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. 227 Heat Wave 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. It is 228 Helicopter capable of moving vertically and horizontally, the direction of motion being controlled by the pitch of the rotor blades. 229 Heliocentric A model of the solar system where the Sun is at the center, as opposed to the Earth. 230 Heliopause The gradual boundary between the heliosphere and the interstellar gas outside our solar system. The bubble-like region of space dominated by the solar wind, a stream of charged particles released from the upper 231 Heliosphere atmosphere of the Sun. A half of the earth, usually as divided into northern and southern halves by the equator, or into western and eastern halves by 232 Hemisphere an imaginary line passing through the poles. 233 Hertz The international unit of frequency equal to one cycle per second. 234 Hubble Space telescope placed in orbit 1990, named for U.S. astronomer Edwin P. Hubble. 235 Hubble’s Law The observation that the farther away a galaxy is, the faster it is moving away from us. 236 Humidity The amount of water vapor in the air. A tropical cyclone with sustained winds of at least 74 mph. A storm with a violent wind, in particular a tropical cyclone in the 237 Hurricane Caribbean. 238 Hydroclimatology The study of the interactions between the hydrological cycle and climate. 239 Hydrologic Cycle The pathways through which water is cycled in the terrestrial biosphere. 240 Hydrosphere All the waters on the Earth’s surface, such as lakes and seas. Hydrostatic 241 The balance between the gravitational force and the pressure gradient force in a fluid. Equilibrium Instrument that measures water vapor content in the air and communicates changes in humidity visibly and immediately 242 Hygrometer through a graph or a dial. A hypergolic propellant combination used in a rocket engine is one whose components spontaneously ignite when they come 243 Hypergolic into contact with each other. 244 Hypersonic Relating to speeds of more than five times the speed of sound (Mach 5). 245 Ice Age A glacial period characterized by lower global temperatures and ice sheet expansion. 246 Illumination The luminous flux per unit area on an intercepting surface at any given point A satellite instrument that measures and maps the Earth and its atmosphere. Imager data are converted by computer into 247 Imager pictures. 248 Impact crater A crater on a planet or satellite caused by the impact of a meteorite or other object. 249 Impulse A force acting briefly on a body and producing a finite change of momentum. 250 Impulsive flares Impulsive flares accelerate mostly electrons, with some protons. A brief epoch in the early universe, just after the Big Bang, during which the universe underwent an extremely rapid and 251 Inflation Period exponential expansion, proposed by physicist Alan Guth in 1980. 252 Inclination It indicates the angle of the orbit plane to the central body's equator. Part of the electromagnetic spectrum that we cannot see with our eyes but can feel as heat. It is made of waves released by hot 253 Infrared objects, such as stars. We call it infrared because these waves are just a little longer than the wavelengths of red light we can see. 254 Injector The nozzle and valve through which fuel is sprayed into a combustion chamber. 255 Insolation Solar radiation incident upon a unit horizontal surface on or above the Earth's surface. 256 Interferometry A technique used to determine the properties of waves by analyzing the patterns created when they overlap. International Date 257 An imaginary line of longitude 180 degrees east or west of the prime meridian. Line 6 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 258 Interplanetary Between the planets in our solar system. 259 Interstellar Between the stars. Interstellar Medium 260 The matter that exists in the space between the star systems in a galaxy. (ISM) Intertropical 261 Convergence Zone A region near the equator where the trade winds of the Northern and Southern Hemispheres come together. (ITCZ) 262 Ionization The process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons. The layer of the earth's atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio 263 Ionosphere waves. It lies above the mesosphere and extends from about 80 to 1,000 km above the earth's surface. 264 Isobar A line on a map connecting points having the same atmospheric pressure at a given time or on average over a given period. 265 Isotherm A line on a map connecting points having the same temperature at a given time or on average over a given period. 266 Jet Propulsion A method of propulsion that uses the reaction force of a high-speed jet of fluid expelled from a rocket engine. 267 Jet Stream A fast flowing, narrow air current found in the atmospheres of some planets, including Earth. 268 Katabatic Wind A wind that carries high-density air from a higher elevation down a slope under the force of gravity. Kelvin-Helmholtz 269 A type of instability that occurs when there is a velocity difference across the interface between two fluids. Instability A synthetic fibre of high tensile strength used especially as a reinforcing agent in the manufacture of tyres and other rubber 270 Kevlar products. 271 Kuiper Belt A region of the Solar System beyond the orbit of Neptune, believed to contain many small icy bodies. The opposite of El Niño. La Niña happens because of unusually cold sea surface temperatures across the east-central 272 La Niña Equatorial Pacific. During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest United States. A position in space where the gravitational forces of a two-body system, like Earth and the Moon, produce enhanced regions 273 Lagrangian Point of attraction and repulsion. 274 Laminar taking place along constant streamlines, without turbulence. A nocturnal coastal breeze that blows from land to sea. In the evening the water may be warmer than the land, causing 275 Land Breeze pressure differences. The distance north or south of the equator, measured in degrees. The angle between a perpendicular at a location, and the 276 Latitude equatorial plane of the Earth. 277 Lift Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air. It’s not a year, or an amount of time at all. It’s the distance light travels in one year. It’s the same as 5,878,499,810,000 miles (or 278 Light year 9,460,538,400,000,000 meters). When things are very far away, it’s easier to talk about their distance in light years than millions or billions or trillions of miles. A sudden electrostatic discharge during a thunderstorm. A discharge of atmospheric electricity accompanied by a vivid flash 279 Lightning of light. 280 Light-Year The distance that light travels in one year, approximately 9.46 trillion kilometers. Liquefaction is a term used in materials sciences to refer to any process which either generates a liquid from a solid or a gas, or 281 Liquefaction generates a non-liquid phase which behaves in accordance with fluid dynamics. 282 Lithosphere the part of the Earth consisting of the crust and mantle 283 Longitude The angular distance from the Greenwich meridian (0 degrees), along the equator 284 Loss of Signals The inability to receive a satellite signal because the satellite's orbital path has taken it below the antenna's horizon. 285 Lunar Related to Moon 286 Lunar Eclipse An event that occurs when the Earth passes between the Sun and the Moon, and the Earth’s shadow falls on the Moon. The space around a magnet where the magnetic force is active. Earth has a magnetic field and its extension into space helps 287 Magnetic field protect us from space weather. 288 Magnetic Storm A disturbance in the magnetosphere due to solar activity. Magnetohydrodyna 289 The study of the magnetic properties and behavior of electrically conducting fluids. mics Region surrounding a celestial body where its magnetic field controls the motions of charged particles. The Earths magnetic 290 Magnetosphere field is dipolar in nature. The region of space around a planet dominated by its magnetic field, affecting space weather. 291 Maneuver A movement or series of moves requiring skill and care. 292 Mantle The region of the earth's interior between the crust and the core, believed to consist of hot, dense silicate rocks 293 Marine Relating to or found in the sea. 294 Mass The amount of matter something is made of. 7 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad The stuff that everything is made of. Atoms are a tiny bit of matter. Big planets have lots of matter. Even you are made of 295 Matter matter! 296 Mesocyclone A vortex of air within a convective storm. 297 Mesopause The upper boundary of the mesosphere where the temperature of the atmosphere reaches its lowest point The atmospheric layer above the stratosphere, extending from about 50 to 85 kilometers altitude. The temperature generally 298 Mesosphere decreases with altitude. Denoting or relating to rock that has undergone transformation by heat, pressure, or other natural agencies, e.g. in the folding 299 Metamorphic rock of strata or the nearby intrusion of igneous rocks. A small body of matter from outer space that enters the Earth’s atmosphere, becoming incandescent as a result of friction and 300 Meteor appearing as a streak of light. The streak of light caused when a meteoroid enters a planet’s atmosphere and starts to burn from the heat of friction. 301 Meteorite A meteoroid that lands on the surface of a planet. 302 Meteoroid A little chunk of rock in space smaller than a pick up truck. If it were bigger, it would be an asteroid. 303 Meteorology The scientific study of the atmosphere and weather patterns. 304 Microclimate The climate of a very small or restricted area, especially when this differs from the climate of the surrounding area. Electromagnetic radiation with wavelengths between about 1000 micrometers and one meter. Part of the electromagnetic spectrum. These waves of energy are made by stars, the clouds of gas between stars, and supernovae. There is also something 305 Microwave called “cosmic microwave background radiation.” It’s all over the universe, and scientists study it to learn how the universe began. 306 Milky way The Milky Way is the galaxy that contains our Solar System. 307 Missile A missile is a self-propelled precision-guided munition system, as opposed to an unguided self-propelled munition 308 Module A detachable self-contained unit of a spacecraft. The smallest unit of a substance that still acts like the main substance. A molecule can be a single atom or a group of atoms. Water is a substance, and one molecule of water is made of two hydrogen atoms and one oxygen atom, which we write as 309 Molecule H2O. That molecule of water still has the same properties as a glass of water. But if you split it into hydrogen and oxygen, it’s not water any more. 310 Monocopter A monocopter or gyropter is a rotorcraft that uses a single rotating blade. 311 Monsoon A seasonal prevailing wind that brings heavy rains. A natural object that travels around a bigger natural object. Planets can have moons. Dwarf planets can have moons. Even 312 Moon some asteroids have moons! Astronomers usually call them satellites or natural satellites. 313 Nautical Mile A unit of distance (U.S.) equal to exactly 1.852 kilometers or about 6076.1 feet. 314 Neap tide A tide just after the first or third quarters of the moon when there is least difference between high and low water. 315 Nebula A giant cloud of dust and gas in space, some of which are regions where new stars are being born. 316 Neutrino An extremely light (possibly massless) particle that is affected only by the weak force and gravity. 317 Neutron The neutron is a subatomic particle, symbol n , with no net electric charge and a mass slightly larger than that of a proton. A type of stellar remnant that can result from the gravitational collapse of a massive star after a supernova. A very dense star 318 Neutron Star made mostly of neutrons. It has very powerful gravitational force nearby because the whole mass of a star is pulled into one object just a few miles across. 319 Nova A star showing a sudden large increase in brightness and then slowly returning to its original state over a few months. A nozzle is a device designed to control the direction or characteristics of a fluid flow (especially to increase velocity) as it exits 320 Nozzle (or enters) an enclosed chamber Occultation is when a celestial body, such as a planet or moon, passes in front of a more distant star or object, obscuring it 321 Occultation from sight. A spherical shell around our solar system. It may contain more than a trillion icy bodies. Long-period comets (which take 322 Oort Cloud more than 200 years to orbit the sun) come from the Oort Cloud. The gravitationally curved trajectory of an object around a point in space. The curved path that a planet, satellite, or spacecraft 323 Orbit moves as it circles around another object. 324 Orbital Plane An imaginary gigantic flat plate containing an Earth satellite's orbit. 325 Orographic Lift The lifting of an air mass as it flows over a mountain range. Orographic 326 Precipitation that occurs when moist air is lifted over a mountain range. Precipitation 327 Oxidizer One component of fuel used to support the combustion of a rocket propellant. 328 Ozone An almost colorless, gaseous form of oxygen with an odor similar to weak chlorine. 329 Ozone Layer A layer in the Earth’s stratosphere that absorbs most of the Sun’s harmful ultraviolet radiation. 330 Paleoceanography The study of the history of the oceans in the geological past. 331 Paleoclimatology The study of past climates using evidence from tree rings, ice cores, and other sources. 8 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad A cloth canopy which fills with air and allows a person or heavy object attached to it to descend slowly when dropped from 332 Parachute an aircraft, or which is released from the rear of an aircraft on landing to act as a brake. The apparent shift in position of a nearby star against the background of distant objects due to Earth’s orbit around the Sun. 333 Parallax The effect whereby the position or direction of an object appears to differ when viewed from different positions, e.g. through the viewfinder and the lens of a camera. 334 Particle A tiny amount or small piece of something. 335 Payload The instruments that are accommodated on a spacecraft. 336 Penumbra The shadow cast by the earth or moon over an area experiencing a partial eclipse. 337 Perigee Perigee is the point in an orbit where an object is closest to the Earth. 338 Perihelion The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun. 339 Period Time required for a satellite to make one complete orbit. 340 Permeability A quantity measuring the influence of a substance on the magnetic flux in the region it occupies. 341 Perturbations Minor corrections to the Keplerian model of a satellite orbit as an ellipse of constant shape and orientation. 342 Photodissociation The breaking down of a chemical compound by photons. 343 Photometry The measurement of light intensity, often used in the study of stars and other celestial objects. 344 Photon A unit or "particle" of electromagnetic energy, or light. 345 Photosphere The lowest layer of the sun's atmosphere. A disc or short cylinder fitting closely within a tube in which it moves up and down against a liquid or gas, used in an internal 346 Piston combustion engine to derive motion, or in a pump to impart motion. 347 Pitot an open-ended right-angled tube pointing in opposition to the flow of a fluid and used to measure pressure. 348 Planet A large body in outer space that circles around the sun or another star. 349 Planetarium A domed building in which images of stars, planets, and constellations are projected for public entertainment or education. A fourth state of matter -- not a solid, liquid or gas. In a plasma, the electrons are pulled free from the atoms and can move 350 Plasma independently. An orbit with an orbital inclination of near 90 degrees where the satellite ground track will cross both polar regions once 351 Polar Orbit during each orbit. Polestar, also spelled pole star, also called (Northern Hemisphere) North Star, the brightest star that appears nearest to either 352 Polestar celestial pole at any particular time. The comparatively slow torquing of the orbital planes of all satellites with respect to the Earth's axis, due to the bulge of the 353 Precession Earth at the equator which distorts the Earths gravitational field. 354 Prime Meridian An imaginary line running from north to south through Greenwich, England, used as the reference point for longitude. 355 Probe An unmanned exploratory spacecraft designed to transmit information about its environment. 356 Prograde Orbits of the Earth in the same direction as the rotation of the Earth (west-to-east). 357 Propellant A substance used as a reagent in a rocket engine to provide thrust. A mechanical device for propelling a boat or aircraft, consisting of a revolving shaft with two or more broad, angled blades 358 Propeller attached to it. A highly magnetized, rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. An object, 359 Pulsar thought to be a rapidly rotating neutron star. It releases short pulses of radio waves and other electromagnetic radiation. 360 Pyrocumulonimbus A type of cumulonimbus cloud that forms above a source of intense heat, such as a wildfire. 361 Quantum In physics, a quantum (plural: quanta) is the minimum amount of any physical entity involved in an interaction. A very energetic and distant active galactic nucleus, with a supermassive black hole at its center. Compact area in the center of 362 Quasar a massive galaxy that is around a supermassive black hole. They are some of the brightest objects in the universe and can be observed across the entire electromagnetic spectrum. In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field, postulated as an explanation of 363 Quintessence the observation of an accelerating rate of expansion of the universe, rather than due to a true cosmological constant. The energy or particles released from sources like radioactive materials, explosions, and chemical reactions. This includes 364 Radiation energy waves on the electromagnetic spectrum. 365 Radiative Forcing The change in energy flux in the atmosphere due to changes in factors like greenhouse gas concentrations. 366 Radiative Transfer The process of energy transfer in the form of radiation, significant in understanding climate dynamics. An electrical impulse sent through the atmosphere at radio frequency. Part of the electromagnetic spectrum. Radio waves are around us here on Earth, and they’re out in space too. These waves are low energy. We use them every time we listen to the 367 Radio Wave radio. They’re used to talk to satellites, too. They are also common in outer space, since they are sent out by forming stars, pulsars, supernovae, the sun, and even colliding galaxies. 368 Radioactive How we describe some atoms that are unstable. They change into different kinds of atoms and release lots of energy. 369 Radiometer An instrument for detecting or measuring the intensity or force of radiation. 9 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 370 Radiometry The measurement of optical radiation, including light and infrared emissions. 371 Radiotelescope A telescope that detects radio waves from astronomical objects. 372 Rain Shadow A dry area on the leeward side of a mountainous area. The reddening of light from a star that is moving away from us, due to the Doppler effect. The phenomenon where light from 373 Red shift an object is increased in wavelength, or shifted to the red end of the spectrum, indicating that the object is moving away from the observer. 374 Relative Humidity The amount of moisture in the air compared to what the air can hold at that temperature. The technology of acquiring data and information about an object or phenomena by a device that is not in physical contact 375 Remote Sensing with it. 376 Renewable Energy Energy from sources that are naturally replenishing, such as solar, wind, and hydroelectric power. 377 Resolution A measure of the ability to separate observable quantities. 378 Retrograde Orbit An east-to-west orbit of Earth (Earth spins west to east). 379 Revolve Move in a circle on a central axis. A nondimensional co-efficient that measures the compression of air due to scaling. This allows scale models to be tested in 380 Reynold's Number wind tunnels 381 Roche Limit The minimum distance to which a celestial body can approach another larger body without being torn apart by tidal forces. 382 Rocketry The branch of science that deals with rockets and rocket propulsion. 383 Rossby Waves Large-scale meanders in high-altitude winds that are a major influence on weather. 384 Rotation Process of the Earth turning on its axis. Rotation determines day and night, and the length of the day. 385 Sampling The process of obtaining a sequence of discrete digital values from a continuous sequence of analog data. 386 Sastrugi Sharp, irregular grooves or ridges formed on a snow surface by wind erosion and deposition. An artificial body placed in orbit around the Earth or another planet to collect information or for communication. An object 387 Satellite that orbits another object. A moon is actually a satellite. We also say satellite to refer to spacecraft people build that orbit Earth, other planets, moons, asteroids, or other objects out in space. Satellite 388 A procedure by which satellites are used to locate precise objects or particular points on Earth positionning The degree or extent to which something is dissolved or absorbed compared with the maximum possible, usually expressed as 389 Saturation a percentage. A system thal optically scans its detector(s) across a scene and records or stores the data in a two-dimensional format to form 390 Scanner an image. The process by which electromagnetic radiation interacts with and is redirected by the molecules of the atmosphere, ocean, or 391 Scattering land surface. Local coastal wind that blows from the ocean to land. Sea breezes usually occur during the day, because the heating 392 Sea Breeze differences of land and sea cause pressure differences. 393 Sea Level The datum against which land elevation and sea depth are measured. Mean sea level is the average of high and low tides. Each of the four divisions of the year (spring, summer, autumn, and winter) marked by particular weather patterns and 394 Season daylight hours, resulting from the earth's changing position with regard to the sun. 395 Sedimentary rock Rock formed from consolidated clay deposits 396 Seismic Relating to or denoting geological surveying methods involving vibrations produced artificially by explosions. 397 Sensor Device that produces an output (usually electrical) in response to stimulus such as incident radiation. A small mechanical device, which upon receiving a signal from a radio or timer will perform an action such as the movement 398 Servo of a pushrod. 399 Shear A strain produced by pressure in the structure of a substance, when its layers are laterally shifted in relation to each other. 400 Signal Electrical impulses, sound or picture elements, etc., received or transmitted. 401 Singularity A point in space-time where gravitational forces cause matter to have an infinite density and zero volume. 402 Sleet Precipitation in the form of ice pellets. A sudden eruption of intense high-energy radiation from the sun’s surface. A burst of energy and particles from the sun. It 403 Solar Flare releases gases, radiation waves, and magnetic storms. 404 Solar Panel A piece of material that can capture sunlight and turn it into electricity. 405 Solar system A set that includes a star and all of the matter that orbits it, including planets, moons, asteroids, comets, and other objects. A stream of charged particles released from the upper atmosphere of the sun. The constant stream of particles and energy 406 Solar Wind emitted by the sun. Either of the two times in the year, the summer solstice and the winter solstice, when the sun reaches its highest or lowest 407 Solstice point in the sky at noon, marked by the longest and shortest days. Sonic boom is an impulsive noise similar to thunder. It is caused by an object moving faster than sound, about 750 miles per 408 Sonic Boom hour at sea level. 10 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad Space launch is the earliest part of a flight that reaches space. Space launch involves liftoff, when a rocket or other space 409 Space Launch launch vehicle leaves the ground, floating ship or midair aircraft at the start of a flight. NASAs manned, recoverable spacecraft designed to be used as a launch vehicle for Earth-orbiting experiments and as a short- 410 Space Shuttle term research platform. The conditions in space that can affect Earth, satellites, and space travel. Space weather is mostly the result of solar wind and 411 Space weather solar storms. 412 Spacecraft A vehicle used for traveling in space. 413 Span The long (side-to-side) dimension of a wing. 414 Spar A long, thin, structural member of a airframe. 415 Spectrometer An instrument that separates measurements into different energies or frequencies, producing a spectrum. An analytical method used to measure how much a chemical substance absorbs light by measuring the intensity of light as a 416 Spectrophotometry function of wavelength. 417 Spectroscope an apparatus for producing and recording spectra for examination. 418 Spectroscopy A technique used to analyze the light spectrum emitted or absorbed by substances, revealing their composition. 419 Speed of Light Light is the fastest thing in the universe. It travels 186,282 miles (299,792,458 meters) every second. 420 Stability The tendency of a rocket to move in a straight line in the direction it is pointed at launch. 421 Stall The angle of maximum lift for an airfoil. A ball of shining gas, made mostly of hydrogen and helium, held together by its own gravity. Turning hydrogen into helium 422 Star creates the energy that makes stars shine. 423 Strain A force tending to pull or stretch something to an extreme or damaging degree. 424 Stratocumulus A type of low-level cloud characterized by large, dark, rounded masses. 425 Stratopause The boundary between the stratosphere and the mesosphere, marking a transition in temperature profile. The second major layer of Earth’s atmosphere, just above the troposphere. Region of the atmosphere between 426 Stratosphere the tropsphere and mesosphere, having a lower boundary of approximately 8 km at the poles to 15 km at the equator and an upper boundary of approximately 50 km. 427 Stress Pressure or tension exerted on a material object. 428 Subsatellite Point Point where a straight line drawn from a satellite to the center of the Earth intersects the Earth's suface. 429 Sun The star in the center of our solar system. Temporary magnetic disturbances in the photosphere. They appear dark because temperatures are considerably lower than in 430 Sun Spot surrounding areas. 431 Sun Synchronous The area observed by a satellite as it orbits the Earth. 432 Supermassive How we describe objects that have a million times (or more!) mass than our sun. A supernova is a powerful and luminous explosion that occurs at the end of a star's life cycle. This event marks the death of a 433 Supernova star and can result in a dramatic increase in brightness, often outshining entire galaxies for a short period. 434 Surge A sudden powerful forward or upward movement, especially by a crowd or by a natural force such as the tide. 435 Sustainability Meeting the needs of the present without compromising the ability of future generations to meet their own needs. 436 Swath The area observed by a satellite as it orbits the Earth. The amount of angle that the leading edge of a wing has been shifted back from a line perpendicular to the airframe of a 437 Sweep Back model. 438 T max The time interval between ignition and maximum thrust 439 Taper A uniform decrease in diameter in a cylindrical of near cylindrical part. Big movements of Earth’s crust. Tectonics creates mountain ranges, deep sea trenches, volcanoes, and earthquakes that can 440 Tectonics cause destructive tsunami waves that can cross oceans. 441 Telemetry Radio signals to and from a spacecraft used to encode and exchange data with a ground station. 442 Telescope An optical instrument designed to make distant objects appear nearer, containing an arrangement of lenses or mirrors or both. A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such 443 Telescope as visible light). 444 Temperature A measure of the warmth or coldness of an environment or substance. 445 Terrestrial On or relating to the earth. 446 Thermal An upward moving column of air caused by surface heating of the ground; a good thing in duration events A steep temperature gradient in a body of water, marked by a layer above and below which the water is at different 447 Thermocline temperatures. 448 Thermodynamics The branch of physics that deals with heat, work, and the forms of energy. Thermohaline 449 A part of the large-scale ocean circulation driven by global density gradients created by surface heat and freshwater fluxes. Circulation 450 Thermosphere The layer of Earth's atmosphere located above the mesosphere, where temperatures increase with altitude. 451 Throat The narrowest cross-section of a rocket motor's nozzle. 452 Thrust The propulsive force developed by a rocket motor during the rocket's powered ascent. 11 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad A storm with thunder and lightning and typically heavy rain or hail. Local storm resulting from warm humid air rising in an 453 Thunderstorm unstable environment. Air may start moving upward because of unequal surface heating, the lifting of warm air along a frontal zone, or diverging upper-level winds (these diverging winds draw air up beneath them). A rapidly rotating column of air that extends from a thunderstorm to the ground. A twisting, spinning funnel of low pressure 454 Tornado air. 455 Transducer A device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa. The condition of crossing the sonic barrier, from the initial appearance of local shock waves (typically around Mach 0.8 to 0.9), 456 Transonic extending to speeds where all local airflow becomes supersonic (typically Mach 1.05 to 1.2). 457 Tropopause The boundary between the troposphere and the stratosphere. The lower atmosphere, to a height of 8-15 km above Earth, where temperature generally decreases with altitude, clouds form, 458 Troposphere precipitation occurs, and convection currents are active. 459 Tsunami A series of ocean waves with extremely long wavelengths caused by large-scale disturbances. Amachine for producing continuous power in which a wheel or rotor, typically fitted with vanes, is made to revolve by a fast- 460 Turbine moving flow of water, steam, gas, air, or other fluid. 461 Typhoon A tropical cyclone occurring in the western Pacific or Indian oceans. a mysterious object seen in the sky for which it is claimed no orthodox scientific explanation can be found, often supposed to 462 UFO be a vehicle carrying extraterrestrials. Part of the electromagnetic spectrum. It’s called ultraviolet because the waves are shorter than violet light. We can’t see 463 Ultraviolet ultraviolet light with our eyes, but some birds and insects can. Our sun emits ultraviolet radiation, and it can give you a sunburn if you’re outside without sunblock for too long. Ultraviolet (UV) 464 A form of electromagnetic radiation with a wavelength shorter than that of visible light but longer than X-rays. Radiation Ultraviolet A type of electromagnetic radiation with a wavelength shorter than that of visible light. The energy range just beyond the 465 Radiation violet end of the visible spectrum. The fully shaded inner region of a shadow cast by an opaque object, especially the area on the earth or moon experiencing the 466 Umbra total phase of an eclipse. Uncertainty The principle, formulated by Heisenberg, that one can never be exactly sure of both the position and the velocity of a particle; 467 principle the more accurately one knows the one, the less accurately one can know the other. 468 Universal time The local time at the 0 meridian passing through Greenwich, England; it is t he same everywhere. 469 Universe All of space and time, and everything in it. It’s everything ever! 470 Vaccum A space absent of matter or nearly so. An empty space that doesn't have any matter. 471 Van Allen Belts Two layers of charged particles held in place by Earth’s magnetic field. 472 Variable Star A star whose brightness as seen from Earth fluctuates. The beginning of spring in the Northern Hemisphere. The time/day that the sun crosses the equatorial plane going from 473 Vernal Equinox south to north. 474 Virtual particle In quantum mechanics, a particle that can never be directly detected, but whose existence does have measurable effects. 475 Visible light The part of the electromagnetic spectrum that we can see with our eyes. It’s all the colors of the rainbow. 476 Volcano A mountain or hill that has an opening where lava, rock fragments, or gas erupt from deep inside a planet or moon. 477 Vortex A mass of whirling fluid or air, especially a whirlpool or whirlwind. 478 Vorticity A measure of the rotation of fluid particles in a flow field. 479 Walker Circulation A conceptual model of the air flow in the tropics in the lower atmosphere. 480 Warm Front The leading edge of a warmer mass of air, replacing a cooler mass of air. A way energy moves from one place to another. Sometimes waves move materials the way water ripples in a pond move the water. Other times, waves don’t move anything around when they transfer energy. For example, X-rays and other waves on 481 Wave the electromagnetic spectrum don’t make any ripples when they move energy from place to place. We classify waves based on how long their wavelengths are. A wavelength is the distance from peak to peak (or valley to valley) of the wave. 482 Wavelength The distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave. 483 Weather The state of the atmosphere at a particular place and time, including temperature, humidity, precipitation, and wind. 484 Weather cocking Tend to turn to head into the wind. 485 Weather Vane An instrument used to indicate wind direction. 486 White Dwarf A small, very dense star that is typically the size of a planet. 487 Wind A natural motion of the air, especially a noticeable current of air moving in the atmosphere parallel to the Earth's surface. 488 Wind Chill The perceived decrease in air temperature felt by the body on exposed skin due to the flow of air. 489 Wind Shear A difference in wind speed and direction over a relatively short distance in the atmosphere. 490 Winglets Small fin or wing-like extensions attached to the ends of the wings of an aircraft. 12 of 13  World Space Week 2024 Space Education Research Lab National Center of GIS and Space Applications Institute of Space Technology, Islamabad 491 Xenon A heavy, colorless, and odorless noble gas used in certain types of lighting and in ion propulsion systems. 492 X-Planes The 'X' stands for experimental; the series of US Government experimental planes starting with the Bell X-1 493 X-ray Astronomy The study of astronomical objects at X-ray wavelengths. Radiation with lots of energy made by very hot gases, stars, neutron stars, and gas around blackholes. X-rays have so much 494 X-Rays energy they can pass though solid materials. They are part of the electromagnetic spectrum. 495 Yarkovsky Effect A force acting on a rotating body in space, caused by the anisotropic emission of thermal photons. 496 Yellow Dwarf A small, main-sequence star, like our Sun, that is in the process of converting hydrogen into helium. 497 Zenith The point in the sky or celestial sphere directly above an observer. 498 Zephyr A gentle, mild breeze. 499 Zodiacal Light A faint, diffuse, and roughly triangular white glow seen in the night sky, caused by sunlight scattered by interplanetary dust. 500 Zonal Flow Atmospheric circulation pattern in which the east-west component of the wind is dominant. 13 of 13