The term light year, refers to a measure of longitude which is used in the field of astronomy, and for this reason it is not correct to say that something or someone took a light year, since the correct thing would be, that is one light year from. The light year is the unit of measurement par excellence used in astronomy. The concept of a light year is not difficult at all to understand, however the name itself can lead to great confusion.
To be a little more specific, a light year is the distance that light travels in the course of a year. Light can travel at almost 300 thousand meters per second, for that reason, in an Earth year it travels 9,467,280,000,000 kilometers, that is, approximately ten million million kilometers.
The use of this measure within astronomy is due to the simple fact that the notion of light years allows us to work with simpler figures when distances are very wide enough, such as when we want to establish the distance between planets and other stars. Since to be able to express distances such as 70 or 100 light years, a large number of digits would be required if units such as meters and even kilometers themselves were to be used.
A concrete example is that of planet Earth with respect to Proxima Centauri, a star that is closer to the sun. According to experts, the Earth is located about 4.22 light years from Proxima Centauri. In other words, it takes 4.22 years for light to travel the distance between our planet and that star. In this way, if a person manages to visualize today, from Earth, the light that Proxima Centauri emits, they are actually seeing the light that came out more than 4 years ago from this star. That is, if Proxima Centauri, in At some point, it ceases to exist and therefore ceases to emit light, on Earth it would take more than four years to know this event.
