What is a light year?

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Anyway, in their everyday life we ​​measure the distance: the nearest supermarket to the home of relatives in another city, to the state border, and so on.However, when it comes to the vast outer space, it turns out that the use of familiar values ​​such as kilometers irrationally.And it is not only in the complexity of the resulting perception of huge value, but the number of digits in them.The problem becomes even the writing of the number of zeros.For example, from Mars to Earth, the shortest distance - 55.7 million. Kilometers.Six zeros!But the red planet - one of our nearest neighbors in the sky.How to use the bulky figures that are obtained when calculating the distance to even the nearest stars?And right now we need such a quantity as a light-year.What is it?Now a look.What

1 light year equals?

concept of light year is also closely connected with the relativistic physics, in which the close relationship and mutual dependence of space and time has been set in the early XX century, when collapsed postulates of Newtonian mechanics.Prior to that, the distance values, larger units were formed in the system is simple enough: each represents a set of subsequent units of smaller order (centimeters, meters, kilometers, and so on).In the case of a light-year away it was tied to time.Modern science knows that the speed of light in a vacuum is constant.Moreover, it is the maximum speed in nature, acceptable in modern relativistic physics.That these ideas were laid in the basis of the new value.A light year is the distance that the light beam passes over the earth one calendar year.A kilometer is about 9.46 * 1015 kilometers.Interestingly, the nearest celestial body, the moon, the photon covers the distance of 1.3 seconds.Before the sun - about eight minutes.But before the next nearest star, Alpha Centauri and Proxima, for about four light-years away.

a fantastic distance.There is in astrophysics and a larger measure of space.A light-year is about one-third of a parsec, more substantial units interstellar distances.

speed of light in different conditions

By the way, there is also such a feature that photons can be distributed at different speeds in different environments.We already know how fast they fly in a vacuum.And when they say that a light-year is the distance light travels in a year of overcoming have in mind is a blank space.However it is interesting to note that in other conditions, the rate of light can be smaller.For example, in the air scatter photons with a somewhat lower rate than in a vacuum.What exactly - it depends on the state of the atmosphere.Thus, in a gas-filled environment is light year would be somewhat less important.However, it would be slightly different from that adopted.