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Learn about everything in the universe.
From the Big Bang to the bones in your hand. Clear, illustrated articles on space, Earth, life, the body and the laws of nature.
Today's reading · Planets & the Solar System
Saturn
The ringed planet is the jewel of the solar system, and its moons include a world with methane lakes and another that sprays its ocean into space.
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Browse by subject
9 fields of science, each with illustrated articles you can read in a few minutes.
Learning paths
Short guided courses. Read the lessons in order, take the quizzes, and track your progress.
Learning path · Beginner
A Tour of the Solar System
Start at the Sun and travel outwards, world by world, to the icy edge where comets are born. Eight lessons, from scorching Mercury to frozen Pluto.
8 lessons · 30 min
Learning path · Beginner
Your Body, System by System
Learn how your body is built and kept alive: the skeleton and muscles that move you, the heart, lungs and gut that fuel you, and the brain and senses that run it all.
11 lessons · 43 min
Learning path · Intermediate
From the Big Bang to You
The biggest story there is, in ten steps: how the universe began, how stars forged the elements, how Earth formed, and how chemistry became life.
10 lessons · 39 min
Learning path · Intermediate
How the Universe Works
The laws behind everything: atoms and the elements, light and sound, gravity, electricity and magnetism, energy, and the strange rules of the quantum world.
8 lessons · 31 min
Learning path · Beginner
The Restless Planet
Earth never sits still. Follow the forces that move continents, raise volcanoes, stir the oceans and drive the weather.
7 lessons · 28 min
Learning path · Beginner
The Animal Kingdom
Meet the great groups of animals, from insects to whales, and discover how they hunt, think, sing and cross the planet.
8 lessons · 27 min
Worth reading today
A fresh selection from across the library, every day.
Plants & Fungi
Trees and Forests
The largest and oldest living things on Earth are trees, and the forests they form hold most of the planet's land species and a vast store of carbon.
Article · 4 min read
Space & the Universe
Black Holes
A black hole is a place where gravity is so strong that nothing, not even light, can escape. They are real, they are common, and in 2019 we finally photographed one.
Article · 3 min read
Plants & Fungi
Flowers and Pollination
Flowers are advertisements aimed at insects, birds and bats. The deal, nectar for pollen delivery, is 130 million years old and feeds most of the world.
Article · 4 min read
The Human Body
Muscles
Six hundred muscles move you, pump your blood and push your food along. Every one of them works the same way: by pulling, never pushing.
Article · 4 min read
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Space & the Universe
Stars, galaxies, black holes and the beginning of everything
Space & the Universe
Black Holes
A black hole is a place where gravity is so strong that nothing, not even light, can escape. They are real, they are common, and in 2019 we finally photographed one.
Article · 3 min read
Space & the Universe
Dark Matter and Dark Energy
Everything we can see makes up only about 5 percent of the universe. The rest is two invisible things we have named but do not understand.
Article · 3 min read
Space & the Universe
Exoplanets: Worlds Around Other Stars
Thirty years ago we knew of no planets beyond our solar system. Now we have found thousands, including some that may have oceans.
Article · 3 min read
Space & the Universe
Galaxies and the Milky Way
Our Sun is one of several hundred billion stars in a spiral galaxy, which is itself one of trillions. Here is the shape of our cosmic home and the neighbourhood around it.
Article · 4 min read
Planets & the Solar System
Our Sun, its eight planets, moons, comets and icy worlds
Planets & the Solar System
Comets, Asteroids and Pluto
Between and beyond the planets drift millions of leftover worlds: rocky asteroids, icy comets and dwarf planets like Pluto. They are the solar system's original building material.
Article · 4 min read
Planets & the Solar System
Jupiter
The largest planet is a world of storms bigger than Earth, a magnetic field that could swallow the Sun, and moons that may hide oceans of liquid water.
Article · 3 min read
Planets & the Solar System
Mars
The red planet is cold, dry and nearly airless today, but rivers once ran across it. Here is what the rovers have found, and why we keep going back.
Article · 4 min read
Planets & the Solar System
Mercury and Venus
The two planets closer to the Sun than Earth could hardly be more different: one a scorched, airless rock, the other a world drowned in acid clouds and crushing heat.
Article · 3 min read
Planet Earth
Oceans, volcanoes, weather and the ground beneath your feet
Planet Earth
Inside the Earth
Beneath your feet lie 6,370 kilometres of rock and metal, hotter than the surface of the Sun at the centre. No one has drilled even one percent of the way down.
Article · 4 min read
Planet Earth
Plate Tectonics and Earthquakes
The continents are moving at the speed your fingernails grow. Where they collide, mountains rise; where they grind past each other, the ground shakes.
Article · 4 min read
Planet Earth
Rocks, Minerals and Fossils
Every pebble is a page in a 4.5-billion-year story. Learn to read the three kinds of rock, the crystals they are made of, and the dead things trapped inside them.
Article · 4 min read
Planet Earth
The Atmosphere
The air is a thin shell of gas, mostly nitrogen, that keeps us warm, shields us from radiation and burns up the rocks that fall from space. Here is how it is built.
Article · 4 min read
Life & Biology
Cells, DNA, evolution and how life began
Life & Biology
Bacteria and Viruses
The smallest living things outnumber everything else combined and run the planet's chemistry. Most are harmless; some keep you alive; a few can kill you.
Article · 4 min read
Life & Biology
Dinosaurs and Mass Extinctions
For 165 million years dinosaurs ruled the land, then nearly all of them vanished in a single catastrophe. Their story is also the story of how life nearly ended five times.
Article · 3 min read
Life & Biology
DNA and Genes
Inside every one of your cells is a two-metre-long molecule carrying the complete instructions to build and run you. Here is how the code works.
Article · 4 min read
Life & Biology
Ecosystems and Food Webs
No living thing lives alone. Energy from the Sun flows through plants, grazers and predators, and the whole web can unravel when one thread is pulled.
Article · 4 min read
Animals
From insects to whales: how creatures live, hunt, think and travel
Animals
Animal Migration
Every year billions of animals set off on journeys of thousands of kilometres, guided by the Sun, the stars, the Earth's magnetism and memory. Here is how, and why.
Article · 4 min read
Animals
Birds
Eleven thousand species of feathered, flying, singing dinosaurs. Birds navigate by the stars, see colours we cannot and cross oceans without landing.
Article · 3 min read
Animals
Insects
Six legs, an outside skeleton and more species than every other kind of animal put together. The world runs on insects, whether we notice or not.
Article · 3 min read
Animals
Mammals
Fur, milk and warm blood unite a group that ranges from a 2-gram bat to a 150-tonne whale. We are mammals too; here is what we share with the rest.
Article · 4 min read
The Human Body
Bones, brain, blood and everything that keeps you alive
The Human Body
Digestion
A nine-metre tube turns a sandwich into the molecules that build and fuel you, with help from acids, enzymes and trillions of bacteria.
Article · 4 min read
The Human Body
Lungs and Breathing
Twenty thousand times a day you draw in air and your lungs, with a surface the size of a tennis court, pass oxygen into your blood. Here is how breathing works.
Article · 4 min read
The Human Body
Muscles
Six hundred muscles move you, pump your blood and push your food along. Every one of them works the same way: by pulling, never pushing.
Article · 4 min read
The Human Body
Skin, Hair and Nails
Your skin is your largest organ: a waterproof, self-repairing shield that senses touch, controls your temperature and makes vitamin D. Hair and nails grow from it.
Article · 3 min read
Plants & Fungi
How green things eat sunlight, and the hidden kingdom of fungi
Plants & Fungi
Carnivorous Plants
In soils too poor to live on, some plants turned the tables and began eating animals. Snap traps, pitfalls, flypaper and suction pumps: the botany of hunting.
Article · 4 min read
Plants & Fungi
Flowers and Pollination
Flowers are advertisements aimed at insects, birds and bats. The deal, nectar for pollen delivery, is 130 million years old and feeds most of the world.
Article · 4 min read
Plants & Fungi
Fungi
Neither plant nor animal, fungi are a kingdom of their own: the planet's recyclers, the partners of nearly every plant, and the source of bread, beer and penicillin.
Article · 4 min read
Plants & Fungi
Photosynthesis: How Plants Eat Light
Every leaf is a solar panel that turns sunlight, water and air into sugar and oxygen. It is the chemical reaction that feeds almost everything alive.
Article · 3 min read
Matter, Energy & Physics
Atoms, light, gravity and the rules the universe runs on
Matter, Energy & Physics
Atoms
Everything you can touch is made of atoms, and atoms are almost entirely empty space. Here is what they are, how we know, and why the tiny nucleus holds so much power.
Article · 4 min read
Matter, Energy & Physics
Electricity and Magnetism
Lightning, compasses, motors, radio and light itself are all one phenomenon. Discovering that they were the same was one of the great unifications in science.
Article · 4 min read
Matter, Energy & Physics
Energy and Heat
Energy cannot be made or destroyed, only moved and changed. Heat is the form it always ends up in, and that one-way street explains why time has a direction.
Article · 4 min read
Matter, Energy & Physics
Gravity
The weakest force in nature holds planets in orbit, lights the stars and shapes the universe. Newton described it; Einstein explained it as the bending of space and time.
Article · 4 min read
Chemistry
Water, reactions, acids and the molecules of life
Chemistry
Acids and Bases
Lemon juice, stomach acid, soap and bleach all sit on one scale: pH. Learn what makes something acidic or alkaline, and why the balance matters in your body and the oceans.
Article · 3 min read
Chemistry
Chemical Reactions
Burning, rusting, cooking and digesting are all chemical reactions: atoms swapping partners to make new substances. Here is what happens and why some reactions go with a bang.
Article · 3 min read
Chemistry
The Chemistry of Life
Every living thing is built from four families of carbon-based molecules: carbohydrates, fats, proteins and nucleic acids. Here is what each one does.
Article · 3 min read
Chemistry
Water: The Strangest Ordinary Substance
Water covers most of the planet and makes up most of your body, yet it breaks nearly every rule a small molecule should follow. Those quirks are why life exists.
Article · 3 min read
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