An extra-system unit of length used in astronomy; 1 S.g. is equal to the distance traveled by light in 1 year. 1 S. g. = 0.3068 parsec = 9.4605 1015 m. Physical encyclopedic dictionary. M.: Soviet encyclopedia. Editor-in-Chief A. M. Prokhorov... ... Physical encyclopedia

LIGHT YEAR, a unit of measurement of astronomical distance equal to the distance that light travels in outer space or in VACUUM for 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 distance to the nearest star (Proxima Centauri) is approximately 4.3 light years. The most distant stars in the Galaxy are located on... ... Modern encyclopedia

Unit of interstellar distances; the path that light travels in a year, i.e. 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. 9.466´1012 km. The distance to the nearest star (Proxima Centauri) is approximately 4.3 light years. The most distant stars in the Galaxy are located on... ... Illustrated Encyclopedic Dictionary

An extra-system unit of length used in astronomy. 1 light year is the distance that light travels in 1 year. 1 light year is equal to 9.4605E+12 km = 0.307 pc... Astronomical Dictionary

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, i.e. 9.46×1012 km... Encyclopedic Dictionary

Light year- a unit of distance equal to the path traveled by light in one year. A light year is equal to 0.3 parsecs... 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 = 9.46073 · 10¹² km. atitikmenys: engl. light... ... Penkiakalbis aiškinamasis metrologijos terminų žodynas

light year- šviesmetis statusas T sritis fizika atitikmenys: engl. light year vok. Lichtjahr, n rus. light year, m pranc. année lumière, f … Fizikos terminų žodynas

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Light year- an unsystematic unit of distance measurement in astronomy.
Numerically, one light year equal to the distance light travels in one year.
More precisely, a light year is the distance that light travels in a vacuum, without the influence of gravitational fields, in one Julian year (365.25 days or 31,557,600 standard seconds).
In Russian literature, the light year is designated “St. g.", in foreign: "ly"

What is one equal to? light year:
Light year in kilometers: 9,460,730,472,580.8 km.
9 460 730 472 580 800 meters
63,241.077 astronomical units (AU)
1 light year is equal to 0.306601 parsecs.

Except light years There are also fractions of a light year: light month, light week, light hour, light minute and light second. They are rare, but it will be interesting to see how different distances are expressed in these units:

The light year is a fairly convenient unit of distance measurement in astronomy. The highest speed at which information can spread in our world is the speed of light. Therefore, distances expressed in light years simultaneously show how quickly one space object may affect another.

For example, you've probably heard that the star Betelgeuse in the constellation Orion is expected to explode in the foreseeable future (in fact, within a few centuries).
Betelgeuse is located at a distance of 495 to 640 light years from us.
If it explodes right now, then the inhabitants of the Earth will see this explosion only in 500-600 years.
And if you see an explosion today, then remember that in fact the explosion occurred around the time of Ivan the Terrible...
This example clearly shows how convenient the light year is - it simultaneously shows both distance and time.

Light year - how many Earth years is it?

How many Earth years are there in a light year? Quite a strange question, but sometimes it comes up... A light year is a measure of distance, as written above, and an earthly year is a measure of time. Therefore, the answer to the question, how many Earth years are in one light year, will be - none :-)

 or tell your friends:

On February 22, 2017, NASA reported that 7 exoplanets were found around the single star TRAPPIST-1. Three of them are in the range of distances from the star in which the planet can have liquid water, and water is a key condition for life. It is also reported that this star system is located at a distance of 40 light years from Earth.

This message caused a lot of noise in the media; some even thought that humanity was one step away from building new settlements near a new star, but this is not so. But 40 light years is a lot, it’s a LOT, it’s too many kilometers, that is, it’s a monstrously colossal distance!

From a physics course, the third escape velocity is known - this is the speed that a body must have at the surface of the Earth in order to go beyond the limits solar system. The value of this speed is 16.65 km/sec. Conventional orbital spaceships start at a speed of 7.9 km/sec and revolve around the Earth. In principle, a speed of 16-20 km/sec is quite accessible to modern earthly technologies, but no more!

Humanity has not yet learned to accelerate spaceships faster than 20 km/sec.

Let's calculate how many years it will take a starship flying at a speed of 20 km/sec to travel 40 light years and reach the star TRAPPIST-1.
One light year is the distance a beam of light travels in a vacuum, and the speed of light is approximately 300 thousand km/sec.

A human-made spaceship flies at a speed of 20 km/sec, that is, 15,000 times slower than the speed of light. Such a ship will cover 40 light years in a time equal to 40*15000=600000 years!

An Earth ship (at the current level of technology) will reach the star TRAPPIST-1 in about 600 thousand years! Homo sapiens has existed on Earth (according to scientists) for only 35-40 thousand years, but here it is as much as 600 thousand years!

In the near future, technology will not allow humans to reach the star TRAPPIST-1. Even promising engines (ion, photon, cosmic sails, etc.), which do not exist in earthly reality, are estimated to be able to accelerate the ship to a speed of 10,000 km/sec, which means that the flight time to the TRAPPIST-1 system will be reduced to 120 years . This is already a more or less acceptable time for flight using suspended animation or for several generations of immigrants, but today all these engines are fantastic.

Even the nearest stars are still too far from people, too far, not to mention the stars of our Galaxy or other galaxies.

The diameter of our Milky Way galaxy is approximately 100 thousand light years, that is, the journey from end to end for a modern Earth ship will be 1.5 billion years! Science suggests that our Earth is 4.5 billion years old, and multicellular life is approximately 2 billion years old. The distance to the closest galaxy to us - the Andromeda Nebula - 2.5 million light years from Earth - what monstrous distances!

As you can see, of all the living people, no one will ever set foot on the earth of a planet near another star.

A light year is the distance that light travels in one year. The International Astronomical Union gave its explanation of the light year - this is the distance that light travels in a vacuum, without the participation of gravity, in a Julian year. The Julian year is equal to 365 days. It is this decoding that is used in scientific literature.

If we take professional literature, then the distance is calculated in parsecs or kilo- and megaparsecs.

There are specific numbers that determine the distance of light hours, minutes, days, etc.

  • A light year is equal to 9,460,800,000,000 km,
  • month- 788,333 million km.,
  • week- 197,083 million km.,
  • day- 26,277 million km,
  • hour- 1,094 million km.,
  • minute- about 18 million km.,
  • second- about 300 thousand km.

This is interesting! From the Earth to the Moon, light travels on average in 1.25 seconds, while its beam reaches the Sun in just over 8 minutes.

Interesting fact about the nature of the universe

The star Betelgeuse in the constellation Orion should explode in the foreseeable future (in fact, within a few centuries).

Betelgeuse is located at a distance of 495 to 640 light years from us.
If it explodes right now, then the inhabitants of the Earth will see this explosion only in 500-600 years.

And if you see an explosion today, then remember that in fact the explosion occurred around the time of Ivan the Terrible...

Earth year

An earthly year is the distance traveled by the earth in one year. If we take into account all the calculations, then one light year is equal to 63242 Earth years. This figure applies specifically to planet Earth; for others, such as Mars or Jupiter, they will be completely different. A light year calculates the distance from one object celestial body to another. The numbers for light years and earth years are so different, although they mean distance.

Galactic distance scales

Light year ( St. G., ly) - non-systemic unit length equal to the distance traveled by light in one year.

More precisely, as defined by the International Astronomical Union (IAU), a light year is equal to the distance that light travels in a vacuum, unaffected by gravitational fields, in one Julian year (equal by definition to 365.25 standard days of 86,400 SI seconds, or 31,557 600 seconds). It is this definition that is recommended for use in popular science literature. In professional literature, parsecs and multiples of units (kilo- and megaparsecs) are usually used instead of light years to express large distances.

Previously (before 1984), a light year was the distance traveled by light in one tropical year, assigned to the epoch 1900.0. The new definition differs from the old one by approximately 0.002%. Since this unit of distance is not used for high-precision measurements, there is no practical difference between the old and new definitions.

Numeric values

A light year is equal to:

  • 9,460,730,472,580,800 meters (approximately 9.46 petameters)
  • 63,241.077 astronomical units (AU)
  • 0.306601 parsecs

Related units

The following units are used quite rarely, usually only in popular publications:

  • 1 light second = 299,792.458 km (exact)
  • 1 light minute ≈ 18 million km
  • 1 light hour ≈ 1079 million km
  • 1 light day ≈ 26 billion km
  • 1 light week ≈ 181 billion km
  • 1 light month ≈ 790 billion km

Distance in light years

The light year is convenient for qualitatively representing distance scales in astronomy.

Scale Value (St. years) Description
Seconds 4 10 −8 The average distance to is approximately 380,000 km. This means that a beam of light emitted from the surface will take about 1.3 seconds to reach the surface of the Moon.
minutes 1.6·10−5 One astronomical unit is equal to approximately 150 million kilometers. Thus, light reaches the Earth in approximately 500 seconds (8 minutes 20 seconds).
Watch 0,0006 The average distance from the Sun is approximately 5 light hours.
0,0016 The devices of the Pioneer and series flying beyond, in about 30 years since the launch, have moved to a distance of about one hundred astronomical units from the Sun, and their response time to requests from the Earth is approximately 14 hours.
Year 1,6 The inner edge of the hypothetical is located at 50,000 a. e. from the Sun, and the outer one - 100,000 a. e. It will take about a year and a half for light to travel the distance from the Sun to the outer edge of the cloud.
2,0 The maximum radius of the region of gravitational influence of the Sun (“Hill Spheres”) is approximately 125,000 AU. e.
4,2 The closest one to us (not counting the Sun), Proxima Centauri, is located at a distance of 4.2 light years. year.
Millennium 26 000 The center of our Galaxy is located approximately 26,000 light years from the Sun.
100 000 The diameter of our disk is 100,000 light years.
Millions of years 2.5 10 6 The closest M31 to us, the famous one, is 2.5 million light years away from us.
3.14 10 6 (M33) is located 3.14 million light years away and is the most distant stationary object visible to the naked eye.
5.8 10 7 The closest one, the Virgo cluster, is 58 million light years away from us.
Tens of millions of light years The characteristic size of galaxy clusters by diameter.
1.5 10 8 - 2.5 10 8 The “Great Attractor” gravitational anomaly is located at a distance of 150-250 million light years from us.
Billions of years 1.2 10 9 The Great Wall of Sloan is one of the largest formations in the world, its dimensions are about 350 Mpc. It will take about a billion years for light to travel from end to end.
1.4 10 10 The size of the causally connected region of the Universe. It is calculated from the age of the Universe and the maximum speed of information transmission - the speed of light.
4.57 10 10 The accompanying distance from the Earth to the edge of the observable Universe in any direction; accompanying radius of the observable Universe (within the framework of the standard cosmological model Lambda-CDM).