Speed of Light Around Earth
Select two cities and watch how long it takes light, sound, jets, and people to travel between them. Light circles the entire planet 7.5 times in one second.
Choose two cities
Travel times: New York to London
Bar width uses log scale. Fastest traveler = widest bar.
Key facts
- ✨Light circles the entire Earth 7.5 times in just one second.
- 🌙Light travels from Earth to the Moon in about 1.3 seconds.
- 🌞Light takes about 8 minutes to reach Earth from the Sun.
- 🚶At walking pace, the New York to London journey would take 46 days.
- 📡Internet data through fiber optic cables travels at about 2/3 the speed of light, because light slows inside the glass fibers.
Cosmic Speed Reference
Speed of Light
Light travels at 299,792 km/s in a vacuum. It can circle the Earth 7.5 times in just one second, reach the Moon in 1.3 seconds, and reach the Sun in about 8 minutes.
Fiber vs Light
Internet data through fiber optic cables travels at about 2/3 the speed of light because light slows down inside the glass fibers. This small delay adds up over long distances.
Sound vs Light
Sound travels at 343 m/s at sea level, nearly a million times slower than light. That is why you see lightning before you hear thunder, even just a few kilometers away.
Why does the ISS move so fast?
The International Space Station orbits Earth at 7.66 km/s, completing one orbit every 90 minutes. At that speed, it experiences 16 sunrises and sunsets every day. Despite this, light is still 39,000 times faster.
The SR-71 Blackbird
The SR-71 was the fastest air-breathing jet ever built, reaching Mach 3.2 (about 0.981 km/s). Even at that extreme speed, light is still 300,000 times faster and completes the same city-to-city trip almost instantly.