What does light-year mean? How much time is 1 light year equal to our earth?

Light years are units of length, mainly used in astronomy.

For the solar system, astronomers use the average distance between the earth and the sun (because the distance between the earth and the sun has been changing, so they can only use the "average" value) as a "ruler", which is called an "astronomical unit". One astronomical unit is equal to 149597870 km.

Astronomical units are suitable for measuring the distance of planets of the solar system, but this ruler is too small to measure the distance between stars.

To this end, astronomers have defined a unit called "light year". Because the speed of light in a vacuum is constant (the speed is about 300 thousand kilometers per second), the distance that light travels in a year is also constant. A light year is the distance that light travels in a vacuum in one year. A light year is about 9.5 trillion kilometers (1 light year = 9.4605284× 1 0/5 meters1light year = 300,000 kilometers per second *365*24*3600 seconds). Astronomers use such a ruler to measure the distance between stars. For example, the nearest known star is about 4.2 light years away from the sun. The farthest star is more than 1000 billion light-years away from the sun.

Light years are units of length, not time.