A non-systemic unit of length used in astronomy; 1 S. g is equal to the distance traveled by light in 1 year. 1 S. y. \u003d 0.3068 parsec \u003d 9.4605 1015 m.Physical encyclopedic Dictionary... M .: Soviet encyclopedia. Chief Editor A. M. Prokhorov. ... ... Physical encyclopedia
LIGHT YEAR, a unit of astronomical distance equal to the distance that light travels in open space or VACUUM in one tropical year. One light year is equal to 9.46071012 km ... Scientific and technical encyclopedic dictionary
LIGHT YEAR, a unit of length used in astronomy: the path traveled by light in 1 year, i.e. 9.466 × 1012 km. The nearest star (Proxima Centaur) is approximately 4.3 light years away. The most distant stars of the Galaxy are located on ... ... Modern encyclopedia
A unit of interstellar distance; the path that light travels in a year, that is, 9.46 × 1012 km ... Big Encyclopedic Dictionary
Light year - LIGHT YEAR, a unit of length used in astronomy: the path traveled by light in 1 year, i.e. Km 9,466´1012. The nearest star (Proxima Centaur) is approximately 4.3 light years away. The most distant stars of the Galaxy are located on ... ... Illustrated Encyclopedic Dictionary
A non-systemic unit of length used in astronomy. 1 light year is the distance that light travels in 1 year. 1 light year equals 9.4605E + 12 km \u003d 0.307 pc ... Astronomical Dictionary
The unit of interstellar distances; the path that light travels in a year, that is, 9.46 · 1012 km. * * * LIGHT YEAR LIGHT YEAR, a unit of interstellar distances; the path that light travels in a year, that is, 9.46X1012 km ... encyclopedic Dictionary
Light year is a unit of distance equal to the path traveled by light in one year. A light year is 0.3 parsec ... Concepts modern natural science... Glossary of basic terms
light year - šviesmetis statusas T sritis Standartizacija ir metrologija apibrėžtis Astronominis ilgio matavimo vienetas, lygus nuotoliui, kurį vakuume nusklinda šviesa per 1 atogrąžinius metus. Žymimas šm: 1 šm \u003d 9.46073 · 10¹² km. atitikmenys: angl. light…… Penkiakalbis aiškinamasis metrologijos terminų žodynas
light year - šviesmetis statusas T sritis fizika atitikmenys: angl. light year vok. Lichtjahr, n rus. light year, m pranc. année lumière, f ... Fizikos terminų žodynas
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The distances between the stars are so great that measuring them in kilometers or miles is an occupation with endless zeros. A familiar measurement system is used to indicate distances in one system. For example, they say that the minimum distance from Earth to Mars is 55.76 million kilometers. With stars, everything is more complicated, and they usually use the concepts of light year and parsec.
Astronomical unit - the unit of measurement of objects accepted in astronomy Solar system and the closest objects of the Universe. The astronomical unit is 149,598,100 km (+ - ~ 750 km), which is approximately equal to the average distance of the Earth from the Sun. Modern observations recorded a gradual increase in the value by 15 cm annually, which is explained by the possible loss of mass by the Sun, the consequences of the solar wind.
Light year - The distance that light travels in one year, in meters, is 9 460 730 472 580 800. In fact, the light of stars that we see on a cloudless night went to our planet for many centuries, and some of them do not exist anymore.
Parsec, it is also "parallax of an angular second" - this is the distance from which the average radius of the Earth's orbit (perpendicular to the line of sight) is seen at an angle of one angular second. Quite simply, parsec \u003d 3.26 light years.
It is interesting that in popular science and science fiction literature, it is customary to use the concept of a light year, and parsecs are usually used only in professional works and research.
(Galaxy UDFj-39546284 - the galaxy farthest from Earth (13.3 billion light years from Earth), in the image taken by the Hubble telescope looks like a red dot)
The closest star to us is Alpha Centauri, which is 4.37 light years from Earth. But to the most distant galaxy (as of December 2012) from the Earth as much as 13.3 billion light years! It turns out that when the sun of this very galaxy (known under the index UDFj-39546284) goes out, mankind will not know about it soon.
Surely, having heard in some fantastic action movie an expression a la "to Tatooine twenty light years”, Many asked legitimate questions. I will voice some of them:
Isn't the year the time?
Then what is it light year?
How many kilometers are there?
How much will it take light year spaceship from Of the earth?
I decided to devote today's article to explaining the meaning of this unit of measurement, comparing it with our usual kilometers and demonstrating the scales with which it operates Universe.
Virtual racer.
Imagine a person, in violation of all the rules, rushing along the highway at a speed of 250 km / h. In two hours he will overcome 500 km, and in four - as much as 1000. Unless, of course, it crashes in the process ...
It would seem that this is speed! But in order to circumnavigate the entire globe (≈ 40,000 km), our rider will need 40 times longer. And this is already 4 x 40 \u003d 160 hours. Or almost a whole week of continuous driving!
In the end, however, we will not say that he covered 40,000,000 meters. Since laziness has always forced us to come up with and use shorter alternative units of measurement.
Limit.
From a school physics course, everyone should know that the fastest rider in The universe - light. In one second, its beam covers a distance of about 300,000 km, and thus it will circle the globe in 0.134 seconds. That's 4,298,507 times faster than our virtual racer!
From Of the earth before Moon light reaches an average of 1.25 s, to Suns its beam will fly in just over 8 minutes.
Colossal, isn't it? But the existence of speeds higher than the speed of light has not yet been proven. therefore learned world decided that it would be logical to measure cosmic scales in units that a radio wave passes over certain time intervals (which light, in particular, is).
Distances.
Thus, light year - nothing more than the distance that a ray of light travels in one year. On an interstellar scale, using distance units less than this does not make much sense. And yet they are. Here are their approximate values:
1 light second ≈ 300,000 km;
1 light minute ≈ 18,000,000 km;
1 light hour ≈ 1,080,000,000 km;
1 light day ≈ 26,000,000,000 km;
1 light week ≈ 181,000,000,000 km;
1 light month ≈ 790,000,000,000 km.
And now, so that you understand where the numbers come from, let's calculate what one is light year.
There are 365 days in a year, 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute. Thus, a year consists of 365 x 24 x 60 x 60 \u003d 31,536,000 seconds. In one second, light travels 300,000 km. Consequently, in a year its ray will cover the distance of 31,536,000 x 300,000 \u003d 9,460,800,000,000 km.
This number is read like this: NINE TRILLION, FOUR SIXTY BILLION AND EIGHT HUNDRED MILLION kilometers.
Of course the exact meaning light year slightly different from what we calculated. But when describing the distances to stars in popular science articles, the highest accuracy is, in principle, not needed, and a hundred or two million kilometers will not play a special role here.
Now let's continue our thought experiments ...
The scale.
Suppose modern spaceship leaves Solar system with the third cosmic speed (≈ 16.7 km / s). First light year it will overcome in 18,000 years!
4,36 light years to the nearest star system ( Alpha Centauri, see image at the beginning) it will overcome in about 78 thousand years!
Our the Milky Way galaxywith a diameter of about 100,000 light years, it will cross in 1 billion 780 million years.
And to the nearest to us big galaxies, spaceship will come only after 36 billion years ...
These are the pies. But in theory even Universe emerged only 16 billion years ago ...
And finally ...
You can start to wonder at cosmic scales without even going beyond Solar system, because it itself is very large. This was shown very well and clearly, for example, by the creators of the project If the moon were only 1 pixel (If the moon was just one pixel): http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html.
On this I, perhaps, will conclude today's article. I am glad to welcome all your questions, comments and wishes in the comments below.
Exploring their own planet, over hundreds of years, people have invented more and more new systems for measuring distance segments. As a result, it was decided to consider one meter as a universal unit of length, and measure a long way in kilometers.
But the onset of the twentieth century posed a new problem for humanity. People began to carefully study space - and it turned out that the vastness of the Universe is so immense that kilometers are simply not suitable here. In the usual units, you can still express the distance from the Earth to the Moon or from the Earth to Mars. But if you try to determine how many kilometers the nearest star is from our planet, the number "overgrows" with an unimaginable number of decimal places.
What is 1 light year?
It became obvious that a new unit of measurement was needed to explore the space of space - and that was the light year. In one second, light travels 300,000 kilometers. Light year - this is the distance that light will travel in exactly one year - and in translation into a more familiar number system, this distance is equal to 9 460 730 472 580.8 kilometers. It is clear that it is much more convenient to use the laconic “one light-year” than to use this huge figure every time in the calculations.
Of all the stars, Proxima Centauri is the closest to us - it is removed "only" by 4.22 light years. Of course, in terms of kilometers, the figure will turn out to be unimaginably huge. However, everything is learned by comparison - if we take into account that the nearest galaxy called Andromeda is distant from Milky way by as much as 2.5 million light-years, the aforementioned star is indeed beginning to seem like a very close neighbor.
By the way, the use of light years helps scientists understand in which corners of the Universe it makes sense to look for intelligent life, and where it is completely useless to send radio signals. After all, the speed of the radio signal is similar to the speed of light - accordingly, a greeting sent to the direction of a distant galaxy will reach its goal only after millions of years. It is more reasonable to expect an answer from closer "neighbors" - objects, the hypothetical response signals of which will reach the terrestrial vehicles at least during a person's life.
How many Earth years is 1 light year?
There is a widespread misconception that a light year is a unit of time. In fact, this is not the case. The term has nothing to do with earthly years, does not correlate with them in any way and denotes only the distance that light travels in one earth year.
Quick answer: not at all.
We are often asked very interesting questions, the answers to which are very non-standard. You see one of these questions in the title. Indeed, how many Earth years are there in one light year? You may be disappointed, but the answer is not at all. How so?
The point is that a light year is not a measure of time, but a measure of distance. To be more precise, a light year is equal to the distance that light travels in a vacuum, without experiencing the influence of gravitational fields, in one Julian year (equal by definition to 365.25 standard days of 86,400 SI seconds, or 31,557,600 seconds), according to definition of the International Astronomical Union.
Now let's try to calculate the distance of a light year. To do this, take a mark of 300 thousand kilometers per second (this is exactly the speed of light) and multiply by 31.56 million seconds (this is how many seconds a year) and we get a huge figure - 9,460,800,000,000 km (or 9,460,000 million kilometers). This fantastic figure means the distance, which is equal to a light year.
- 1 light month ~ 788 333 million km
- 1 light week ~ 197,083 million km
- 1 light day ~ 26 277 million km
- 1 light hour ~ 1,094 million km
- 1 light minute ~ approximately 18 million km
- 1 light second ~ 300 thousand km