Stage 1 of 24
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Stage 1 of 24
Standing still
The journey begins while you are standing still.
Even when you feel completely still, you are always moving. Earth spins on its axis and travels around the Sun, carrying you along with it.
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Walking
A normal brisk walking pace.
At about 5 km/h, time dilation is far too small for any person to notice. Only extremely accurate atomic clocks can detect it.
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Cheetah
The fastest land animal.
During a sprint, a cheetah uses its tail like a steering wheel to stay balanced while making sharp turns at high speed.
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Car
A typical speed on a fast road or motorway.
A car on a motorway travels about the length of an Olympic swimming pool in one second.
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Formula 1 car
A speed reached on the fastest parts of a race track.
On a long straight, a Formula 1 car can go faster than 350 km/h.
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Passenger plane
The normal cruising speed of a modern airliner.
Passenger planes usually fly at around 900 km/h.
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Speed of sound
The speed at which sound moves through air at sea level.
Sound cannot travel through empty space. It needs something to move through, such as air, water or metal.
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Earth’s rotation
The speed at which you move because Earth is spinning.
People at the equator move with Earth’s rotation much faster than people in Poland, even though nobody can feel it.
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SR-71 Blackbird
A legendary spy plane that was the world’s fastest crewed jet for many years.
The SR-71 was so fast that most missiles fired at it could not catch up. Pilots often escaped danger simply by flying faster.
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International Space Station
The orbital speed of the International Space Station.
Astronauts on the ISS get about 45 minutes of daylight and 45 minutes of darkness before seeing another sunrise.
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Apollo
The speed reached by Apollo spacecraft while returning from the Moon.
Apollo capsules returning from the Moon travelled at nearly 40,000 km/h, faster than any other crewed vehicle in history.
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Voyager 1
The speed of Voyager 1, the most distant human-made object from Earth.
Voyager 1 was launched in 1977 and is still moving away from the Sun. It has already travelled beyond the main edge of the Solar System.
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Earth’s orbit
The speed at which Earth travels around the Sun.
While you read this fact, Earth will move several hundred kilometres along its orbit, even though none of us can feel it.
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Meteor
The speed of a meteor entering Earth’s atmosphere.
Meteors can move at more than 70 kilometres per second, faster than you can blink.
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Parker Solar Probe
The fastest human-made object ever built.
To reach its record speed, Parker Solar Probe uses Venus’s gravity again and again like a giant space slingshot.
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Solar wind
A stream of charged particles constantly flowing out from the Sun.
The solar wind can travel at speeds from about 1 to 3 million kilometres per hour.
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Coronal mass ejection
A huge cloud of plasma blasted out from the Sun during an eruption.
In 1859, a powerful coronal mass ejection caused the Carrington Event. Auroras were seen across much of the world, and telegraph systems stopped working in many countries.
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1% of the speed of light
The first step where we start getting close to speeds that can measurably affect time.
Today’s technology cannot reach 1% of the speed of light. Even our fastest space probes are more than 15 times slower.
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20% of the speed of light
A speed where the effects of relativity become clearly measurable.
At this speed, a spacecraft would travel from Earth to the Moon in about six seconds.
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50% of the speed of light
Half the speed of light, where relativity begins to clearly change how time passes.
At this speed, a clock on the spacecraft would begin to fall clearly behind a clock left on Earth.
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75% of the speed of light
A speed where motion changes not only time, but also how the outside world looks.
At this speed, the stars would seem to move toward the direction of travel. More and more of the sky would appear packed into the view ahead.
Stage 22 of 24
Relativistic jet
A powerful stream of matter fired from around an active black hole at almost the speed of light.
The jet does not come from inside the black hole. It is made by matter spinning just outside it before some of that matter falls past the event horizon.
Stage 23 of 24
Electrons in a particle accelerator
Particles pushed by humans to a speed almost equal to the speed of light.
In particle accelerators, electrons can move so close to the speed of light that the difference is hard to write without many decimal places.
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The speed of light limit
The final speed limit of the Universe, according to modern physics.
The speed of light is the same for every observer, no matter how fast they are moving. This is one of the strangest discoveries in modern physics.