light year is a unit of measurement used to calculate distances in astronomical space, that is, where are the planets, stars, comets and so on.
The distances between the stars are gigantic, so to measure the immense dimensions of the Universe it is necessary to apply a special measurement unit: the light year.
The speed of light is 300,000 kilometers per second, so one light second is equal to 300,000 kilometers, and at this speed it would be possible to go around the Earth eight times.
Light travels extremely fast by terrestrial standards. So a light year is the distance light can travel in a year. For example, in a light year, the distance traveled would be approximately 9,460,800,000,000 (nine trillion, four hundred and sixty billion, eight hundred million) kilometers.
Learn more about meaning of the galaxy.
The light from some stars takes years to reach us, so the distances between stars are measured by the unit called the light year.
For example, imagine a star that is a million light years from Earth, its light needed to travel at the speed of light for a million years to reach our location, that is, the light we see from the Earth is a million years back.
The star Sirius, the brightest in the night sky, is eight light-years away from Earth, in fact what we see is the brightness of the star from eight years ago. The Orion Nebula, a cluster that is 1,500 light-years away from Earth, is visible today as it was 1,500 years ago.
See also: O meaning of astronomy.
