Word book
80 space words explained simply, from asteroid to year. Words with a "More" link have a longer page in the full glossary.
A
- Asteroid
- A rocky or metal object that travels around the Sun. Asteroids are much smaller than planets. More
- Asteroid belt
- A wide ring of asteroids between Mars and Jupiter. Most meteorites come from here. More
- Astronaut
- A person who travels into space.
- Astronomer
- A scientist who studies the stars, planets and everything else in space.
- Atmosphere
- The layer of air around a planet. Earth's atmosphere protects us from most space rocks, which burn up in it.
B
- Binoculars
- A tool with two tubes, one for each eye, that makes faraway things look closer. Good for looking at the Moon.
C
- Ceres
- The biggest object in the asteroid belt, about 940 kilometres across. It is a dwarf planet.
- Chondrite
- The most common kind of stony meteorite. Many have tiny round grains inside called chondrules.
- Chondrule
- A tiny round grain inside many meteorites, about the size of a pinhead. It formed as a melted droplet in space. More
- Comet
- A lump of ice and dust that travels around the Sun. Near the Sun it grows a glowing cloud and tails. More
- Constellation
- A group of stars that people imagine as a picture, such as Orion the hunter.
- Core
- The middle part of a planet or a big asteroid. Earth's core is made mostly of iron.
- Crater
- A round bowl in the ground made when a space rock crashes into it. More
- Crescent
- The thin, curved shape of the Moon when only a small part of it is lit.
- Crust
- The thin, rocky outside layer of a planet. We live on Earth's crust.
D
- Dark adaptation
- The way your eyes slowly get better at seeing in the dark. It takes about 20 minutes. More
- Dawn
- The time in the early morning when the sky starts to get light, before sunrise.
- Dusk
- The time in the evening when the sky is getting dark, after sunset.
- Dwarf planet
- A round world that travels around the Sun but is not big enough to count as a planet. Pluto and Ceres are dwarf planets. More
E
- Earth
- Our home planet, the third planet from the Sun.
- Eclipse
- When one object in space blocks the light from another. In a solar eclipse, the Moon passes in front of the Sun.
- Element
- A basic building block of all materials, such as iron, oxygen or carbon.
F
G
- Galaxy
- A huge family of billions of stars. Our galaxy is called the Milky Way.
- Gas
- A material that spreads out to fill any space, like air or steam.
- Geologist
- A scientist who studies rocks and how they formed.
- Gravity
- The pull that every object has on every other object. Gravity keeps us on the ground and keeps the planets going around the Sun.
H
- Hemisphere
- Half of the Earth. The United Kingdom is in the northern hemisphere.
- Horizon
- The line where the land or sea seems to meet the sky.
- Howardite
- A kind of meteorite from the asteroid Vesta, made of broken pieces of rock pressed together. This website is named after it.
I
- Impact
- When one object crashes into another, such as a space rock hitting the ground.
- Iron
- A strong, heavy metal. Many meteorites contain iron, and some are made almost entirely of it.
- Iron meteorite
- A meteorite made mostly of iron and nickel metal. It came from the metal core of an asteroid. More
J
- Jupiter
- The biggest planet in the Solar System, a giant ball of gas. It is the fifth planet from the Sun.
L
- Lava
- Melted rock that flows out on the surface of a planet or moon, then cools and hardens.
- Lunar
- To do with the Moon. A lunar meteorite is a rock from the Moon that landed on Earth. More
M
- Magnet
- An object that pulls on iron. Magnets stick to most meteorites because they contain iron.
- Mantle
- The thick layer of rock inside a planet, between the crust and the core.
- Mars
- The fourth planet from the Sun. It looks red because its dust contains rusty iron. More
- Martian
- To do with Mars. A Martian meteorite is a rock from Mars that landed on Earth. More
- Mercury
- The smallest planet, and the closest to the Sun.
- Meteor
- The streak of light made when a piece of space rock or dust rushes into our air. Also called a shooting star. More
- Meteor shower
- A night when lots of shooting stars appear, because Earth is passing through a trail of comet dust. More
- Meteorite
- A rock or piece of metal from space that has landed on Earth. More
- Meteoroid
- A small piece of rock or dust travelling through space, before it reaches Earth's air. More
- Micrometeorite
- A tiny meteorite, smaller than a grain of sand. More
- Milky Way
- Our galaxy. On very dark nights it looks like a faint, cloudy band across the sky.
- Mineral
- A natural solid material with its own particular make-up, such as quartz or olivine. Rocks are made of minerals.
- Moon
- A natural object that travels around a planet. Earth has one Moon. More
- Moon phase
- The shape of the lit part of the Moon that we see, which changes through the month.
- Museum
- A place that looks after interesting objects so that people can see and study them. Many museums have meteorites.
N
- Neptune
- The eighth planet from the Sun, and the furthest. It is a cold, blue-green giant.
- New Moon
- When the Moon is between Earth and the Sun and its lit side faces away from us, so we cannot see it. A good time to watch for shooting stars.
- Nickel
- A silvery metal. It is mixed with iron in meteorites, which helps scientists tell them apart from many Earth rocks.
O
- Olivine
- A green mineral found in many meteorites and in Earth's rocks.
- Orbit
- The path an object follows around another, such as Earth around the Sun. More
P
- Planet
- A large, round world that travels around a star. Our Solar System has eight planets. More
- Pluto
- A small, icy dwarf planet far beyond Neptune.
R
- Radiant
- The point in the sky that the shooting stars in a meteor shower seem to come from. More
- Rocket
- A machine that pushes hot gas out of one end to fly in the other direction. Rockets carry spacecraft into space.
- Rover
- A robot vehicle with wheels that explores the surface of another world, such as Mars.
S
- Sample
- A small piece of something, kept so that scientists can study it.
- Satellite
- Anything that travels around a planet. The Moon is a natural satellite. Machines sent into orbit are artificial satellites.
- Saturn
- The sixth planet from the Sun, a gas giant with bright rings of ice.
- Scientist
- A person who finds out how the world works by asking questions, testing ideas and looking carefully.
- Shooting star
- Another name for a meteor. It is not really a star at all.
- Solar System
- The Sun and everything that travels around it: planets, moons, asteroids, comets and dust.
- Space
- Everything beyond Earth's air. It is almost completely empty.
- Spacecraft
- A machine built to travel in space. Some carry people, and many are robots.
- Star
- A giant ball of hot, glowing gas. The Sun is our nearest star.
- Stony meteorite
- A meteorite made mostly of rock. Most meteorites are stony. More
- Sun
- The star at the centre of our Solar System. It gives Earth light and warmth.
T
- Telescope
- A tool that collects light to make faint, faraway things look brighter and closer.
U
- Uranus
- The seventh planet from the Sun. It spins tipped over on its side.
V
- Venus
- The second planet from the Sun, and the brightest planet in our sky.
- Vesta
- A large asteroid about 525 kilometres across. Howardites and some other meteorites come from it. More
W
- Widmanstätten pattern
- The criss-cross pattern of metal crystals seen in many iron meteorites when they are cut, polished and treated in a laboratory.
Y
- Year
- The time Earth takes to travel once around the Sun: about 365 days.