Meaning of Light Year

The concept of light year tends to be confusing. According to abbreviationfinder, the presence of the term year causes many people to associate the expression with a temporal unit. A light year, however, is a measure of length used in the field of astronomy, and for this reason one does not speak of “taking a light year” but of “being one light year from.”

Specifically, a light year is the distance that light travels in a vacuum in the span of a year. Since light travels 299 792 458 meters per second in a vacuum, a light year is a huge distance: it equals 9 460 730 472 580.8 kilometers.

As you can see, the use of the notion of light years allows working with simpler numbers when the distances are very large, as occurs between planets and other stars. Expressing distances such as 40 or 200 light years, for example, would require many digits if you were to use units such as meters or even kilometers.

Take the case of planet Earth with respect to Proxima Centauri, the star that is closest to the sun. According to astronomers, Earth is located about 4.22 light years from Proxima Centauri. This means that it takes 4.22 years for light to travel the distance between our planet and the aforementioned star. Thus, if a person today observes, from Earth, the light emitted by Proxima Centauri, he is actually seeing the light that came out more than 4 years ago from the star. If Proxima Centauri, for some reason, ceases to exist and emit light, on Earth It would take us more than four years to notice its disappearance.

It should be noted that when the distances are less, similar units such as light minutes or light seconds can be used.

The light minute is, as can be deduced, the distance that an electromagnetic wave travels in a vacuum in the course of a minute, which is equivalent to 17 987 547 480 meters. Among the astronomical distances that are usually expressed using this unit (instead of light year) are that of certain space probes and that between the Sun and Earth (approximately 8.31 light minutes). In the field of astronomy, the light minute is very useful to indicate the delay that can exist between two given points.

The distance expressed by the second light, meanwhile, is 299 792 458 meters. This unit of measurement is used to refer to the distance between our planet and certain celestial bodies, such as the Moon (1.2 light seconds), the Sun (500 light seconds), Alpha Centauri (137 million light seconds)), Pluto (20,000 light seconds) and the Andromeda galaxy (80 trillion light seconds), among many others.

This alternative to the light year is suitable for measuring distances within the Solar System, provided they are not less than the diameter of Jupiter. In the calculation of intergalactic distances, the light year or the parsec (parallax of one arc second) must be used, while for intergalactic there is the megaparsec (a multiple of the parsec, which is equivalent to about 3.26 million). light years).

Outside the field of astronomy, it is common to use this unit of measurement figuratively, to make qualitative comparisons between people or products with the intention of accentuating the great distance that exists between the different elements. Let’s see some example sentences: “I would like my student to go directly to the next course, since she is light years away from her classmates and I am afraid that she will get bored to the point of getting frustrated”, “Between these two televisions there is no point of comparison, since their technologies are light years away. ”

Light Year