📖 Astronomical Glossary
All astronomical terms explained simply and clearly
3
3I/ATLAS
An interstellar object discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS).
A
accretion disk
A rotating disk of gas and dust around a star or black hole.
Active Galaxy
A galaxy with a supermassive black hole at its center that emits large amounts of energy.
aerosols
Tiny particles suspended in the air, like dust or pollution.
AfSA
African Space Agency, an agency responsible for promoting space development in Africa.
AI
Artificial intelligence, where machines can do tasks that usually require human intelligence.
air quality
The measure of pollutants in the air.
airplane internet
Internet access available on airplanes.
Alnilam
A bright blue supergiant star in the constellation Orion.
Alnitak
A blue supergiant star in the constellation Orion.
National Geographic Kids: First Big Book of Space
Perfect introduction to space for young readers. Filled with stunning images and fascinating facts.
Amazon
A very large river and rainforest in South America.
Amazon Rainforest
The world's largest rainforest, located in South America.
Andromeda Galaxy
The closest big galaxy to our Milky Way galaxy.
Apep
A binary star system with a spectacular dust plume shaped by the stars' colliding stellar winds.
Argonaut
A program that seeks to enable sustainable development through space activities.
Ariane 6
A European launch vehicle used to send satellites into space.
Asteroid Defense
Efforts to protect Earth from potential asteroid impacts.
asteroids
Small, rocky objects that orbit the Sun, mostly found between Mars and Jupiter.
Astrobiology
The study of the origin, evolution, distribution, and future of life in the universe.
Astronomy
The study of space and the objects in it.
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Complete set of telescope eyepieces and filters for enhanced viewing. Compatible with most telescopes.
Astrophotography
Taking pictures of astronomical objects, like stars and galaxies.
astrophysical jets
Powerful streams of matter ejected from black holes or young stars.
astrophysics
The branch of physics that deals with celestial objects, space, and the physical universe as a whole.
ATLAS
Asteroid Terrestrial-impact Last Alert System, a robotic astronomical survey and early warning system.
atmosphere
The layer of gases surrounding a planet or other celestial body.
atmospheric dynamics
The study of how air moves in the atmosphere, creating weather patterns.
aurora
A natural light display in the sky, usually seen in polar regions.
Australia
A country and continent in the Southern Hemisphere.
Awards
Recognition of achievement or excellence.
B
BepiColombo
A European-Japanese mission to study the planet Mercury.
Astrophysics for People in a Hurry
Neil deGrasse Tyson's bestselling introduction to the universe. Essential reading for anyone curious about space.
big bang
The event that started the universe.
binary stars
Two stars that orbit around each other.
black holes
Regions of spacetime with such strong gravity that nothing, not even light, can escape.
Brazil
A country in South America.
brown dwarf
An object that is bigger than a planet but smaller than a star, and doesn't have enough mass to burn fuel like a star.
C
Carbon sink
A natural or artificial reservoir that accumulates and stores carbon dioxide from the atmosphere.
career
A long-term professional journey or occupation.
Cassini
A spacecraft that explored Saturn and its moons.
Chamaeleon
A constellation in the southern sky.
China
A country in East Asia.
Endurance: A Year in Space, A Lifetime of Discovery
Astronaut Scott Kelly's memoir of spending a record-breaking year aboard the International Space Station.
climate
The typical weather conditions in an area over a long period of time.
Climate change
Long-term shifts in temperatures and weather patterns, largely due to human activities.
climate models
Computer programs that simulate the Earth's climate to predict future changes.
clouds
Visible masses of condensed water vapor suspended in the atmosphere.
Cluster Mission
A European Space Agency mission to study the Earth's magnetosphere using four identical spacecraft.
CME
Coronal Mass Ejection, a large release of plasma and magnetic field from the Sun.
collision
When two objects hit each other.
comet
A ball of ice and dust that orbits the Sun, often leaving a tail of gas and dust.
communication
The process of conveying information or ideas.
condensation
The change of water from its gaseous form (water vapor) into liquid water.
LEGO NASA Apollo Saturn V Rocket
Detailed LEGO model of the iconic Saturn V rocket. Perfect for display and space history enthusiasts.
cooling
The process of becoming colder.
copernicus
An Earth Observation program coordinated by the European Union.
Copernicus Program
An Earth Observation program led by the European Union.
Copernicus Sentinel-2
A satellite that takes pictures of Earth to monitor land, vegetation and water.
cosmic microwave background
The afterglow of the Big Bang, a faint radiation that fills the universe.
cosmology
The study of the origin, evolution, and future of the universe.
Cosmos
The universe, seen as a well-ordered whole.
crescent moon
The phase of the Moon when it appears as a thin sliver in the sky.
Crescent Nebula
A cloud of gas and dust in space that looks like a crescent moon.
CubeSat
A small, standardized satellite used for research and education.
National Geographic Planisphere Star Finder
Essential tool for identifying constellations and stars. Perfect for beginners learning the night sky.
Cyprus
An island country in the Eastern Mediterranean.
D
Danakil Depression
A desert area in Ethiopia, known as one of the hottest and lowest places on Earth.
dark matter
A mysterious substance that makes up most of the mass in the universe, but does not interact with light.
Dark Nebula
A cloud of dust and gas in space that blocks light from stars behind it.
Deep Space
The region of space beyond our solar system, far, far away.
Deforestation
The clearing of forests.
desert
A barren or desolate area, especially one with little or no rainfall.
Dione
A moon of Saturn.
disaster management
The organization and management of resources and responsibilities for dealing with all humanitarian aspects of emergencies.
disaster relief
Aid given to people affected by a natural disaster.
Metal Earth Apollo Lunar Module 3D Model Kit
Precision 3D metal model kit of the Apollo Lunar Module. Challenging build for space enthusiasts and model makers.
Dust Devils
Whirling columns of dust and sand that occur on dry land.
dwarf galaxies
Small galaxies that often orbit larger galaxies.
E
early universe
The period of time shortly after the Big Bang.
Earth Observation
Using satellites and other technologies to monitor and study the Earth's environment and resources.
EarthCARE
A European Space Agency satellite to study the role of clouds and aerosols in the Earth's climate.
earthquake
A sudden and violent shaking of the ground caused by movements within the Earth's crust.
Ecosystems
A biological community of interacting organisms and their physical environment.
Enceladus
A moon of Saturn that has a subsurface ocean and shoots water into space.
Environment
The surroundings or conditions in which a person, animal, or plant lives or operates.
environmental monitoring
Tracking and assessing the condition of the environment using various methods.
National Geographic Kids: First Big Book of Space
Perfect introduction to space for young readers. Filled with stunning images and fascinating facts.
eruption
A sudden outbreak of something, like a volcano.
ESA
The European Space Agency.
eta-w
Estimated time of arrival for a satellite or spacecraft at a location or event
Ethiopia
A country in the Horn of Africa.
Euclid
A European Space Agency mission designed to map the geometry of the Universe
Euclid Telescope
A space telescope designed to map the geometry of the universe.
Europe
A continent located in the Northern Hemisphere.
European Space Agency
An international organization dedicated to space exploration.
exomars
A joint ESA and Roscosmos mission to Mars.
exoplanet
A planet that orbits a star outside of our solar system.
Orion Telescope Eyepiece and Filter Kit
Complete set of telescope eyepieces and filters for enhanced viewing. Compatible with most telescopes.
Extragalactic
Outside of our galaxy, the Milky Way.
Extremophiles
Organisms that can live in extreme environments, like very hot or very salty places.
F
Flooding
When water overflows onto normally dry land.
Fornax
A constellation in the southern sky.
Funding
Money provided for a particular purpose, like scientific research.
FutureEO
European Space Agency program dedicated to Earth observation
G
Gaia
A European Space Agency mission to create a 3D map of our galaxy.
galactic evolution
How galaxies form, change, and develop over billions of years, like how a baby grows into an adult.
galactic halo
A large, roughly spherical region surrounding a spiral galaxy, containing sparse stars and dark matter.
galaxies
Huge collections of stars, gas, and dust held together by gravity.
Astrophysics for People in a Hurry
Neil deGrasse Tyson's bestselling introduction to the universe. Essential reading for anyone curious about space.
Galaxy
A huge collection of stars, gas, and dust held together by gravity.
galaxy formation
The process by which galaxies form and evolve over time.
Galileo
A European global navigation satellite system.
Geology
The study of the Earth's physical structure, substance, history, and the processes that act on it.
geomagnetic storm
A disturbance in Earth's magnetic field caused by solar activity.
globular cluster
A spherical collection of stars, tightly bound together by gravity.
GPS
Global Positioning System, used for navigation.
gravitational lensing
When gravity bends light, making distant objects appear bigger or distorted, like looking through a magnifying glass.
gravitational waves
Ripples in space-time caused by accelerating massive objects.
gravity
The force that attracts objects with mass towards each other.
Endurance: A Year in Space, A Lifetime of Discovery
Astronaut Scott Kelly's memoir of spending a record-breaking year aboard the International Space Station.
Greece
A country in southeastern Europe with thousands of islands throughout the Aegean and Ionian seas.
H
Halloween
A celebration observed in many countries on October 31.
Himalayas
The highest mountain range in the world, located in Asia.
Hubble
The Hubble Space Telescope, a telescope orbiting Earth that takes stunning pictures of space.
Hubble Space Telescope
A telescope in space that takes amazing pictures of the universe.
Huygens
A probe that landed on Saturn's moon Titan, the first to land on a moon in the outer solar system.
HydroGNSS
A technique that uses signals from navigation satellites to measure water levels and soil moisture.
I
images
Visual representations of something.
Impact Crater
A bowl-shaped depression on a planet or moon, caused by a collision with an asteroid or comet.
in-flight wifi
Internet access available during a flight.
LEGO NASA Apollo Saturn V Rocket
Detailed LEGO model of the iconic Saturn V rocket. Perfect for display and space history enthusiasts.
Infrared Astronomy
Studying space by looking at infrared light, which can reveal objects that are hidden from normal vision.
innovation
The introduction of something new.
international collaboration
Different countries working together on a project.
International Collaboration
When different countries work together on a project, like building a space station.
Internship
A short-term work experience for students or recent graduates.
interstellar
Between the stars.
interstellar comet
A comet that comes from outside our solar system.
Interstellar Dust
Tiny particles of solid matter found in the space between stars.
Ionized Gas
Gas that has been heated to such a high temperature that its atoms have lost electrons.
IRIDE
An Italian constellation of satellites for Earth Observation.
National Geographic Planisphere Star Finder
Essential tool for identifying constellations and stars. Perfect for beginners learning the night sky.
Italy
A country in Southern Europe.
J
James Webb Telescope
A powerful space telescope used to study the early universe and exoplanets.
JAXA
Japan Aerospace Exploration Agency, the Japanese space agency.
Juice
Jupiter Icy Moons Explorer, a European Space Agency mission to explore Jupiter's icy moons.
JWST
James Webb Space Telescope, a large infrared telescope in space.
L
Lake Carnegie
A salt lake in Western Australia.
lakes
Large bodies of water surrounded by land.
LDN 1641
A dark nebula in the Orion Molecular Cloud Complex.
light
Electromagnetic radiation that allows us to see.
Lunar Lander
A spacecraft designed to land on the Moon.
Metal Earth Apollo Lunar Module 3D Model Kit
Precision 3D metal model kit of the Apollo Lunar Module. Challenging build for space enthusiasts and model makers.
M
M dwarf
A small, cool, and faint type of star.
M15
A globular cluster in the constellation Pegasus.
M77
A barred spiral galaxy located in the constellation Cetus.
Magnetic Field
A field of force surrounding a magnet or electric current.
magnetosphere
The region around a planet that is controlled by the planet's magnetic field.
Mars
The fourth planet from the Sun, often called the Red Planet.
marsexpress
A European Space Agency mission to study the planet Mars.
Mercury
The closest planet to the Sun.
merger
When two or more galaxies collide and combine into one.
Messier 31
The Andromeda Galaxy, the closest large galaxy to our Milky Way.
National Geographic Kids: First Big Book of Space
Perfect introduction to space for young readers. Filled with stunning images and fascinating facts.
microgravity
The condition of being weightless or having very low gravity.
Milky Way
The galaxy that contains our solar system.
Ministerial Council
A high-level governing body that makes decisions for an organization.
Mintaka
A bright star in the constellation Orion.
moon
A natural satellite that orbits a planet, like Earth's Moon.
Moons
Natural satellites orbiting planets.
multiverse
The idea that our universe is just one of many universes that exist.
N
NASA
The National Aeronautics and Space Administration, the U.S. space agency.
Natural Disaster
A sudden event that causes widespread damage, loss of life, or suffering.
Navigation
The process of finding your way from one place to another.
Orion Telescope Eyepiece and Filter Kit
Complete set of telescope eyepieces and filters for enhanced viewing. Compatible with most telescopes.
near-Earth objects
Asteroids and comets whose orbits bring them close to Earth.
nebula
A cloud of gas and dust in space where stars are born or where stars die.
NGC 1055
A spiral galaxy located in the constellation Cetus.
NGC 1316
A lenticular galaxy in the constellation Fornax.
NGC 1317
A spiral galaxy located in the constellation Fornax.
NGC 3370
A spiral galaxy located in the constellation Leo.
NGC 4535
A spiral galaxy located in the constellation Virgo.
NGC 6888
The Crescent Nebula, a cosmic bubble formed by a Wolf-Rayet star.
NIRPS
A high-precision spectrograph to measure radial velocities of stars in the near infrared, it is mounted on the ESO 3.6m telescope at La Silla.
O
observable universe
The part of the universe we can see from Earth, limited by how far light has traveled since the Big Bang.
Astrophysics for People in a Hurry
Neil deGrasse Tyson's bestselling introduction to the universe. Essential reading for anyone curious about space.
ocean monitoring
Tracking and studying the condition of the oceans.
Ocean Worlds
Planets or moons with oceans, potentially habitable environments in our solar system and beyond.
Open Days
Events where an organization opens its doors to the public.
Opportunity
A Mars rover that explored the Martian surface for many years.
orbital pollution
The accumulation of space debris in orbit around Earth.
Orion
A prominent constellation containing bright stars like Betelgeuse and Rigel.
ozone
A layer in Earth's atmosphere that protects us from the sun's harmful ultraviolet rays.
P
particle physics
The study of the fundamental constituents of matter and energy and their interactions.
planet formation
The process by which planets are born from protoplanetary disks around young stars.
planetary defense
Efforts to protect Earth from potential asteroid or comet impacts.
Endurance: A Year in Space, A Lifetime of Discovery
Astronaut Scott Kelly's memoir of spending a record-breaking year aboard the International Space Station.
planetary nebula
Nebula formed from a dying star.
Plato
A crater on the Moon.
podcast
A digital audio or video file made available on the Internet for downloading or listening to.
pollution
The presence or introduction into the environment of a substance or thing that has harmful or poisonous effects.
protoplanetary disks
A rotating disk of gas and dust surrounding a young star, where planets may form.
Q
quasar
A very luminous active galactic nucleus, powered by a supermassive black hole.
R
radar
A system that uses radio waves to detect objects and measure their distance and speed.
red supergiant
A very large and luminous star that has exhausted its core hydrogen fuel.
relativity
Einstein's theory about how gravity works, and how space and time are connected.
remote sensing
Gathering information about an object or area from a distance, typically using satellites or aircraft.
LEGO NASA Apollo Saturn V Rocket
Detailed LEGO model of the iconic Saturn V rocket. Perfect for display and space history enthusiasts.
Rhea
A moon of Saturn.
Richat Structure
A prominent circular feature in the Sahara desert of Mauritania.
Rings
A structure of ice and rock that orbits a planet, like Saturn.
River
A large natural stream of water flowing in a channel to the sea, a lake, or another such stream.
Rocket Science
The study of how rockets work, and how to design and build them.
S
Sahara Desert
The largest hot desert in the world, located in Africa.
sand dunes
Hills of sand formed by wind.
Satellite
An object that orbits a planet, used for communication, observation, and navigation.
satellite communication
Using satellites to transmit signals for television, phone, and internet.
satellite image
A picture of Earth taken from a satellite.
National Geographic Planisphere Star Finder
Essential tool for identifying constellations and stars. Perfect for beginners learning the night sky.
satellite imagery
Pictures of Earth and space taken by satellites.
Satellites
Objects orbiting Earth used for communication, navigation, and observation.
Saturn
A planet known for its beautiful rings.
Science
The study of the natural world based on observation and experimentation.
Science Event
An organized event focused on science, such as a conference or exhibition.
Sea Level Rise
The increase in the average height of the world's oceans, largely due to climate change.
security
Measures taken to protect something from harm or danger.
Sentinel-1
A satellite mission focused on radar imaging for Earth observation.
Sentinel-1D
A satellite used for Earth observation, with instruments that send and receive radar signals.
Sentinel-2
A satellite that takes pictures of Earth to help us understand our environment.
Metal Earth Apollo Lunar Module 3D Model Kit
Precision 3D metal model kit of the Apollo Lunar Module. Challenging build for space enthusiasts and model makers.
Sentinel-4
A satellite instrument for monitoring air pollution over Europe.
Sentinel-5P
A satellite that monitors air pollution across the globe.
Sentinel-6B
Copernicus Sentinel mission that measures Sea Surface Height.
simulation
A computer model that mimics a real-world process or system.
SMILE mission
A joint ESA and CAS mission to study the interaction between the Earth's magnetosphere and the solar wind.
SOHO
A satellite that studies the Sun.
Solar activity
Changes in the Sun's surface, such as sunspots and flares.
Solar Orbiter
A spacecraft that studies the Sun up close.
Solar Physics
The study of the Sun.
solar storm
A disturbance on the Sun that can release energy in the form of flares, coronal mass ejections, and solar wind.
National Geographic Kids: First Big Book of Space
Perfect introduction to space for young readers. Filled with stunning images and fascinating facts.
Solar Storms
Disturbances on the Sun that can affect Earth.
solar system
The Sun and all the planets, moons, asteroids, and comets that orbit it.
solar wind
A stream of charged particles constantly emitted by the Sun.
Solar Wind
A stream of charged particles flowing from the Sun.
space
The area beyond Earth's atmosphere.
Space Agency
A government organization responsible for a country's space program.
Space Budget
The amount of money allocated to a space program or activity.
space debris
Pieces of defunct satellites and other objects that are orbiting the Earth.
space engineering
Designing, building, and testing spacecraft and related technologies.
space environment
The conditions in space, including radiation, vacuum, and microgravity.
Orion Telescope Eyepiece and Filter Kit
Complete set of telescope eyepieces and filters for enhanced viewing. Compatible with most telescopes.
Space Exploration
The investigation of space by human-crewed and uncrewed spacecraft.
space food
Food specially prepared for astronauts to eat in space.
Space Industry
Businesses involved in space-related activities, such as satellite manufacturing and launch services.
Space Investment
Investing money in space-related technologies and activities.
Space Safety
Protecting space assets and activities from threats like space debris and solar storms.
Space Strategy
A plan for how a country or organization will achieve its goals in space.
space sustainability
Using space in a way that does not harm the space environment and ensures its use for future generations.
space technology
Tools and techniques used to explore and use space.
Space weather
Conditions in space that can affect Earth, like solar flares and geomagnetic storms.
spectroscopy
The study of light to understand the composition and properties of objects in space.
Astrophysics for People in a Hurry
Neil deGrasse Tyson's bestselling introduction to the universe. Essential reading for anyone curious about space.
spiral galaxy
A galaxy that has a central bulge and spiral arms.
Sri Lanka
An island country in South Asia.
standard model
A theory that describes the fundamental particles and forces in the universe.
star clusters
Groups of stars that were born together from the same cloud of gas and dust.
Star Formation
The process by which stars are born from clouds of gas and dust.
stars
Giant balls of hot gas that produce light and heat.
Stellar Evolution
The life cycle of a star, from its birth in a nebula to its eventual death as a white dwarf, neutron star, or black hole.
sulfur dioxide
A pollutant gas released by volcanoes and industrial processes.
Sun
The star at the center of our solar system that provides light and heat to Earth.
Supergranulation
A pattern of convection cells on the Sun's surface, larger than granules.
Endurance: A Year in Space, A Lifetime of Discovery
Astronaut Scott Kelly's memoir of spending a record-breaking year aboard the International Space Station.
Supermassive Black Hole
A black hole with a mass millions or billions of times the mass of the Sun, found at the center of most galaxies.
supernova
The explosion of a star.
sustainability
Meeting the needs of the present without compromising the ability of future generations to meet their own needs.
T
Technology
The application of scientific knowledge for practical purposes.
telescopes
Instruments used to observe distant objects.
TESS
Transiting Exoplanet Survey Satellite, a space telescope that searches for exoplanets.
Tipping point
A critical threshold in a system that, when exceeded, leads to large and often irreversible changes.
Titan
Saturn's largest moon, known for its thick atmosphere and liquid methane lakes.
training
The action of teaching a person a particular skill or type of behavior.
U
universe
Everything that exists, including all matter, energy, space, and time.
LEGO NASA Apollo Saturn V Rocket
Detailed LEGO model of the iconic Saturn V rocket. Perfect for display and space history enthusiasts.
V
Viasat
A communication satellite company.
Vinci Engine
A European rocket engine used on the Ariane 6 launch vehicle.
visualization
The use of computer graphics to create images, diagrams, or animations to represent data.
volcano
A mountain that opens downward to a reservoir of molten rock below the surface of the Earth.
W
Water
A transparent, odorless, tasteless liquid, essential for life.
water cycle
The continuous movement of water on, above, and below the surface of the Earth, like rain falling and then evaporating.
wave
A disturbance that transfers energy through matter or space.
Weather
The state of the atmosphere at a place and time as regards heat, dryness, sunshine, wind, rain, etc.
Webb
Short for the James Webb Space Telescope, a powerful space telescope.
Webb telescope
A powerful space telescope that sees infrared light, allowing us to study distant galaxies and stars.
National Geographic Planisphere Star Finder
Essential tool for identifying constellations and stars. Perfect for beginners learning the night sky.
witch's broom
A supernova remnant in the constellation Cygnus.
Wolf-Rayet Star
A very hot and bright type of star that is rapidly losing mass.
X
Xanthe Terra
A large region on Mars marked by ancient outflow channels.
Celestron NexStar 130SLT Computerized Telescope
Computerized telescope perfect for beginners. Features a 130mm aperture and automated tracking to explore the night sky.
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