Create an animated lesson
On requestThis article is free to read. Creating a lesson uses your daily or stored credits; review the language and settings before starting.
What is the speed of light?
ScienceLesson on requestFree to read
Quick answer
The speed of light is the fastest anything can travel — about 300,000 kilometers per second in a vacuum. It's a fundamental limit of the universe, and nothing carrying information or mass can go faster. Light travels about 300,000 km per second in a vacuum.
Key things to understand
- Light travels about 300,000 km per second in a vacuum.
- It's the universe's ultimate speed limit.
- Nothing with mass can reach it.
- It links space and time in Einstein's relativity.
People also ask
How fast is the speed of light?
About 299,792 kilometers per second in a vacuum — roughly 300,000 km/s.
Why can't anything go faster than light?
Relativity shows that reaching light speed would require infinite energy for anything with mass.
How long does light take to reach us from the Sun?
About 8 minutes and 20 seconds to travel from the Sun to Earth.