Physics
Speed of Light
Quick fact
Light travels about 300,000 kilometers in one second—enough to circle Earth 7.5 times. But even at that breakneck pace, it still takes 8 minutes for sunlight to reach our planet.
Why this is interesting
You see lightning before you hear thunder—but did you know that even the light from that bolt isn't instant? The speed of light is the universe's built-in speed limit, and nothing with mass can ever catch up. What makes this number so special?