Exploring their own planet, for hundreds of years, people have been inventing 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 to measure a long distance in kilometers.
But the twentieth century has set before mankind new problem. People began to carefully study space - and it turned out that the expanses of the universe are so vast that kilometers are simply not suitable here. In familiar 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 figure “acquires” an unimaginable number of decimal places.
What is 1 light year equal to?
It became obvious that a new unit of measurement was needed to study the spaces of space - and it became a light year. Light travels 300,000 kilometers in one second. Light year - this is the distance that light will travel in exactly one year - and in terms of a more familiar number system, this distance is 9,460,730,472,580.8 kilometers. It is clear that using the laconic "one light year" is much more convenient than using this huge figure every time in the calculations.
Of all the stars, Proxima Centauri is closest to us - it is “only” 4.22 light years away. Of course, in terms of kilometers, the figure will turn out to be unimaginably huge. However, everything is known in comparison - given that the nearest galaxy called Andromeda is as much as 2.5 million light years away from the Milky Way, the aforementioned star really begins 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. intelligent life, and where to send radio signals is completely useless. After all, the speed of a radio signal is similar to the speed of light - accordingly, a greeting sent towards a distant galaxy will reach its goal only after millions of years. It is more reasonable to wait for an answer from closer "neighbors" - objects whose hypothetical response signals will reach earthly vehicles at least during a person's life.
1 light year is how many Earth years?
There is a widespread misconception that the light year is a unit of time. Actually, it is not. The term has nothing to do with earth years, does not correlate with them in any way and denotes only the distance that light travels in one earth year.
As you know, to measure the distances from the Sun to the planets, as well as between the planets, scientists came up with an astronomical unit. What is light year?
First of all, it should be noted that a light year is also a unit of measurement adopted in astronomy, but not of time (as it may seem, judging by the meaning of the word “year”), but of distance.
What is a light year
When scientists were able to calculate the distances to the nearest stars, it became obvious that in the stellar world the astronomical unit was inconvenient for use. Let's say for starters that the distance from the Sun to the nearest star is about 4.5 light years. This means that the light from our Sun to the nearest star (it is called, by the way, Proxima Centauri) flies 4.5 years! How big is this distance? We will not bore anyone with mathematics, we will only note that in a second particles of light fly 300,000 kilometers. That is, if you send a signal with a flashlight towards the Moon, this light will be seen there in less than a second and a half. Light travels from the Sun to the Earth in 8.5 minutes. And how much then do the rays of light fly by in a year?
Let's just say: a light year is about 10 trillion kilometers(a trillion is a one followed by twelve zeros). More precisely, 9,460,730,472,581 kilometers. If recalculated in astronomical units, then it will be approximately 67,000. And this is only to the nearest star!
It is clear that in the world of stars and galaxies the astronomical unit is not suitable for measurements. It is easier to operate in calculations with light years.
Applicability in the stellar world
For example, the distance from Earth to the brightest star in the sky, Sirius, is 8 light years. And the distance from the Sun to polar star is about 600 light years. That is, the light from us gets there for 600 years. It will be approximately 40 million astronomical units. For comparison, we point out that the size (diameter) of our Galaxy - the Milky Way - is about 100,000 light years. Our closest neighbor spiral galaxy, called the Andromeda Nebula, is 2.52 million light-years distant from Earth. It is very inconvenient to state this in astronomical units. But there are objects in the Universe that are 15 billion light-years distant from us. Thus, the radius of the observable universe is 13.77 billion light years. BUT complete universe, as is known, extends beyond the observed part.
By the way, the diameter of the observable universe is not at all 2 times more radius as you might think. The point is that space expands over time. Those distant objects that emitted light 13.77 billion years ago flew even further away from us. Today they are more than 46.5 billion light-years away. Doubling that, we get 93 billion light years. This is the true diameter of the observable universe. So the size of the part of space that is being observed (and which is also called the Metagalaxy) is increasing all the time.
It makes no sense to measure such distances in kilometers or astronomical units. To be honest, light years don't quite fit here either. But nothing better people not yet figured out. The numbers are so huge that only a computer can handle them.
Definition and essence of the light year
In this way, a light year (st. g.) is a unit of length, not time, which is the distance traveled sunbeam for a year, i.e. for 365 days. This unit of measurement is very convenient for its clarity. It allows you to answer the question, after what period of time you can expect a response if you send an electromagnetic message to a certain star. And if this period is too long (for example, it is a thousand years), then there is no point in such actions.
In order to understand the meaning of the concept of "light year", you first need to remember school course physics, especially the section that deals with the speed of light. So the speed of light in a vacuum, where it is not affected various factors, such as gravity and magnetic fields, suspended particles, refraction of a transparent medium, etc., is 299,792.5 kilometers per second. It must be understood that in this case light means perceived human vision.
Less known units distance measurements are light month, week, day, hour, minute and second.Long enough light was considered an infinite quantity, and the first person to calculate the approximate speed of light rays in a vacuum was the astronomer Olaf Römer in mid-seventeenth century. Of course, his data were very approximate, but the very fact of determining final value speed. In 1970, the speed of light was determined to within one meter per second. More accurate results have not been achieved so far, as there were problems with the error of the meter standard.
Light year and other distances
Since the distances in are huge, measuring them in customary units would be irrational and inconvenient. Based on these considerations, a special light year was introduced, that is, the distance that light travels in the so-called Julian year (equal to 365.25 days). Considering that each day contains 86,400 seconds, it can be calculated that in a year a ray of light covers a distance of several more than 9.4 kilometers. This value seems huge, however, for example, the distance to the nearest star to the Earth, Proxima Centauri, is 4.2 years, and the diameter of the galaxy Milky Way exceeds 100,000 light years, that is, those visual observations that can be made now reflect a picture that existed about a hundred thousand years ago.
A beam of light covers the distance from the Earth to the Moon in about a second, but sunlight reaches our planet for more than eight minutes.
In professional astrophysics, the concept of a light year is rarely used. Scientists mainly operate with units such as the parsec and the astronomical unit. A parsec is the distance to an imaginary point from which the radius of the Earth's orbit is seen at an angle of one arc second (1/3600 of a degree). Medium radius orbit, that is, the distance from the Earth to the Sun, is called the astronomical unit. A parsec is about 3 light years or 30.8 trillion kilometers. astronomical unit approximately equal to 149.6 million kilometers.
Do you know why astronomers don't use the light year to calculate distances to distant objects in space?
A light year is a non-systemic unit for measuring distances in outer space. It is ubiquitous in popular books and textbooks on astronomy. However, in professional astrophysics, this figure is used extremely rarely and often to determine distances to nearby objects in space. The reason for this is simple: if you determine the distance in light years to distant objects in the Universe, the number will be so huge that it will be impractical and inconvenient to use it for physical and mathematical calculations. Therefore, instead of a light year, professional astronomy uses such a unit of measurement as , which is much more convenient to operate when performing complex mathematical calculations.
Definition of the term
We can find the definition of the term "light year" in any astronomy textbook. A light year is the distance that a ray of light travels in one Earth year. Such a definition may satisfy the amateur, but the cosmologist will find it incomplete. He will notice that a light year is not just the distance that light travels in a year, but the distance that a beam of light travels in 365.25 Earth days in vacuum, without being affected by magnetic fields.
A light year is 9.46 trillion kilometers. This is the distance a ray of light travels in a year. But how did astronomers achieve this? exact definition beam path? We will talk about this below.
How is the speed of light determined?
In ancient times, it was believed that light propagates in the universe instantly. However, beginning in the seventeenth century, scholars began to doubt this. Galileo was the first to doubt the above proposed statement. It was he who tried to determine the time during which a ray of light travels a distance of 8 km. But due to the fact that such a distance was negligible for such a value as the speed of light, the experiment ended in failure.
The first major shift in this issue was the observation of the famous Danish astronomer Olaf Römer. In 1676, he noticed the difference in the time of an eclipse depending on the approach and removal of the Earth to them in outer space. This observation Roemer has successfully connected with the fact that the farther the Earth moves away from, the longer it takes the light reflected from them to travel the distance to our planet.
essence this fact Roemer caught exactly, but he did not succeed in calculating the reliable value of the speed of light. His calculations were wrong, because in the seventeenth century he could not have accurate data on the distance from the Earth to other planets. solar system. These data were determined somewhat later.
Further advances in research and determination of the light year
In 1728, the English astronomer James Bradley, who discovered the effect of stellar aberration, was the first to calculate the approximate speed of light. He determined its value at 301 thousand km / s. But this value was inaccurate. More advanced methods for calculating the speed of light have been produced regardless of space bodies- on the ground.
Observations of the speed of light in vacuum using a rotating wheel and a mirror were made by A. Fizeau and L. Foucault, respectively. With their help, physicists managed to get closer to the real value of this quantity.
Accurate speed of light
Scientists managed to determine the exact speed of light only in the last century. Based on Maxwell's theory of electromagnetism, with the help of modern laser technology and calculations, corrected for the refractive index of the ray stream in the air, scientists were able to calculate the exact value of the speed of light 299,792.458 km / s. This value is still used by astronomers. Further, to determine the light day, month and year was already a matter of technology. By simple calculations, scientists got the figure of 9.46 trillion kilometers - that is how long it would take for a beam of light to fly around the length of the earth's orbit.
A light year is the distance that light travels in one year.. The International Astronomical Union gave its explanation for 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 interpretation that is used in the scientific literature.
If we take professional literature, then here the distance is calculated in parsecs or kilo- and megaparsecs.
There are specific figures that determined the distance of light hours, minutes, days, etc.
- A light year is 9,460,800,000,000 km,
- month- 788 333 million km.,
- a 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.
It is interesting! From the Earth to the Moon, light reaches an average of 1.25 s, while its beam reaches the Sun in a little more than 8 minutes.
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 Earth 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 refers specifically to the planet Earth, to others, such as Mars or Jupiter, they will be completely different. A light year calculates the distance from a single object celestial body to another. The numbers for light years and earth years are so different, even though they mean distance.
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Quick answer: not at all.
We are often asked very interesting questions, the answers to which are very non-standard.
One of these questions you see in the title. And really, how many Earth years are there in one light year? You may be disappointed, but there is no real answer.
The fact is that a light year is not a measure of time, but a distance measure. To be more precise, a light year is distance distance in a vacuum without gravity fields, one effect julian year(equivalent to 365.25 standard days in 86400 SI seconds or 31557600 seconds) by the International Astronomical Federation,
To do this, we take 300,000 kilometers per second (which is exactly the speed of light) and multiply by 31.56 million seconds (many seconds per year) and we get great amount- 9460800000 000 km (or 9.46 million kilometers). This fantastic number means a distance equal to a light year.
- 1 light month ~ 788,333,000,000 km
- 1 easy week ~ 197,083,000 km
- 1 light day ~ 26,277 million km
- 1 light hour ~ 1,094 million km
- 1 light minute ~ about 18 million km
- 1 light second ~ 300 thousand km
To find out how many kilometers in a light year you need to use a simple web calculator.
In the left box, enter the number of light years of interest you want to convert. In the field on the right you will see the result of the calculation. Just click on the appropriate link to convert light years or miles to other units.
What is "bright summer"
Light year of one-way system (St., ly) equal to the distance, traveled by light in vacuum in one july year(365.25 days).
This term is mainly used in science and fiction, and in the professional environment, the term "parsecs" was adopted with the prefix "kilo" and "mega".
not before 1984, according to the bright year, to understand the distance with the light traveled in the tropical year, now the value has changed by 0.002%, and practical value this difference because very accurate measurements are not made in light years. The speed of light is about 300,000.
km per second and the luminous year is about 10 trillion kilometers (9460.8800 million km). As for the distances, for example, that Sirius has 8 light years from the closest proximity to the star Proxima Centauri - 4.22 light years, and the diameter of the Roman road - our galaxy, which is 100,000 light years.
What is "kilometer"
The kilometer kilometer (km, km) is a plural unit of reference distances and is widely used throughout the world.
One kilometer 1000 meters, 0.621 miles, 0.9374 miles, 1094 yards, 3281 meters, 1.057 x 10 - 13 light years, 6.67 x 10 - 9 astronomical units.
Easy years
For hundreds of years people have been inventing their own planet to invent more and more remote sensing systems. Therefore, it was decided to take into account universal unit one meter long and a long way measurements in kilometers.
But in the next twentieth century, this created a new problem for humanity. People began to carefully study the universe - and it turned out that the size of the universe is so large that miles are simply not suitable here.
In ordinary units, you can express the distance from the Earth to the Moon or from the Earth to Mars. But if you're trying to figure out how far the nearest star is from our planet, the number "grows" with an imperceptible number of characters per decimal point.
What is 1 light year?
It was obvious that a new unit of space exploration was needed - and it's been a bright year.
In a second, light travels 300,000 kilometers. Easy years — this is the distance whose light will travel exactly one year, and when translated into a more familiar system of numbers, this distance is 9,460,730,472,580.8 kilometers. It is clear that the use of a concise "simple flight" is much more convenient than the use of each huge number in the calculations.
Of all the stars closest to us, Proxima Centauri - this was removed only "4.2 light years". Of course, based on kilometer data, there is an unimaginable amount. However, everything is relative - given that the nearest Andromeda galaxy is separated from the Roman road by as much as 2.5 million light years, the star and truth begin to seem very close neighbors.
By the way, the use of light years helps scientists understand in which corners of space it is reasonable to find intelligent life and where it is completely useless to send radio signals.
After all, the speed of a radio signal is similar to the speed of light, so a greeting sent towards a distant galaxy will reach its destination in millions of years. It makes sense to expect a response from neighboring "neighbors" - objects whose hypothetical response signals will reach terrestrial devices even during a person's life.
1 light year - how many earth years?
There is a common misconception that the light year is a unit of time.
Actually it is not. This term has nothing to do with earth years, it does not apply to them and represents only the distance that light travels in one Earth year.
