Anyway, in our daily life wewe measure distances: to the nearest supermarket, to the house of relatives in another city, to the state border and so on. However, when it comes to endless outer space, it turns out that the use of familiar values like kilometers is extremely irrational. And the point here is not only in the complexity of perceiving the resulting gigantic meanings, but in the number of digits in them. The problem is even the very writing of such a number of zeros. For example, from Mars to Earth, the shortest distance is 55.7 million kilometers. Six zeros! But the red planet is one of our closest neighbors in the sky. How can you use the cumbersome figures that you get when calculating the distance even to the nearest stars? And now we need such a magnitude as the light year. How much is he equal? Now we'll figure it out.
What is 1 light-year equal to?
The concept of the light year is also closely related torelativistic physics, in which close connection and mutual dependence of space and time was established at the beginning of the XX century, when the postulates of Newtonian mechanics collapsed. Prior to this, distance values, larger scale units in the system
were formed quite simply: each subsequent was a collection of units of a smaller order (centimeters, meters, kilometers, and so on). In the case of the light year, the distance was tied to the time. Modern science knows that the speed of light in a vacuum is constant. Moreover, it is the maximum speed in nature permissible in modern relativistic physics. It was these ideas that were the basis of the new meaning. The light year is equal to the distance that a ray of light travels in one earthly calendar year. In kilometers this is approximately 9.46 * 10
15 kilometers. Interestingly, to the nearest celestial body, the Moon, the photon overcomes the distance in 1.3 seconds. Before the sun - about eight minutes. But the next few stars, Alpha and Proxima Centauri, are about four light years away.
Just a fantastic distance. There is an even larger measure of space in astrophysics. The light year is approximately one third of the parsec, an even more significant unit of measurement of interstellar distances.
The speed of light in different conditions
By the way, there is also such a feature that photonscan spread with different speeds in different environments. We already know how quickly they fly in a vacuum. And when they say that the light year is equal to the distance overcome by light in a year, they mean empty space. However, it is interesting to note that in other conditions the speed of light can be smaller. For example, in an air environment, photons scatter at a slightly slower rate than in a vacuum. From which one - depends on the specific state of the atmosphere. Thus, in a gas-filled medium, the light year would be equal to a somewhat smaller value. However, it would not significantly differ from the adopted.
