Light Travel Time
Calculate how long it takes light (and radio signals) to travel between Earth and other planets in our solar system.
Distances are approximate average separations from Earth.
Traveling at the speed of light
The Speed Limit of the Universe
Nothing travels faster than the speed of light (approximately 300,000 kilometers per second). This means that space exploration is a conversation with the past.
Communication Lag
When NASA scientists send a command to the Curiosity rover on Mars, it takes several minutes for the signal to reach the planet. If the rover encounters a problem, it might take 20 minutes before Earth even knows about it.
Frequently Asked Questions (FAQ)
How long does it take for light to reach us from the Sun?
On average, it takes about 8 minutes and 20 seconds for sunlight to reach Earth.
Is this the same for radio waves?
Yes. Radio waves are a form of electromagnetic radiation and travel at exactly the same speed as visible light.