Light-time

Summary: It takes light about eight minutes to reach Earth from the Sun, a distance of 150 000 000 (150 million) km (see The speed of light is about 300 000 km/s. Sound travels about a million times slower than light (0.34 km/s in air). Astronomers use ‘light-time’ to measure distances in space. - A light-minute is the distance that light travels in one minute. - A light-year is how far light travels in a year. Tags: science student-book-7 physics Created: 2026-05-21 Last Updated: 2026-05-21

Light-time

It takes light about eight minutes to reach Earth from the Sun, a distance of 150 000 000 (150 million) km (see The speed of light is about 300 000 km/s. Sound travels about a million times slower than light (0.34 km/s in air). Astronomers use ‘light-time’ to measure distances in space. - A light-minute is the distance that light travels in one minute. - A light-year is how far light travels in a year.

Source

This concept is from the [Science Student Book 7](Science Student Book 7/Physics/Light/3.1 Light.md), Physics section.