On February 22, 2017, NASA announced that 7 exoplanets have been 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 the key to life. It is also reported that this star system is located at a distance of 40 light years from Earth.
This message made a lot of noise in the media, it even seemed to some that humanity was one step away from building new settlements near new star, but it's not. But 40 light-years is a lot, it's a LOT, it's too many kilometers, that is, this is a monstrously colossal distance!
From the course of physics, the third cosmic velocity is known - this is the speed that a body must have at the surface of the Earth in order to go beyond solar system. The value of this speed is 16.65 km/s. Ordinary orbiting spacecraft start at a speed of 7.9 km / s, and revolve around the Earth. In principle, a speed of 16-20 km/s is quite affordable for modern earthly technologies, but no more!
Mankind has not yet learned how to accelerate spaceships faster than 20 km/sec.
Let us calculate how many years it will take for a starship flying at a speed of 20 km/s to overcome 40 light years and reach the star TRAPPIST-1.
One light year is the distance that a beam of light travels in a vacuum, and the speed of light is approximately 300,000 km/sec.
Spaceship, made by human hands, flies at a speed of 20 km / s, that is, 15,000 times slower than the speed of light. Such a ship will overcome 40 light years in a time equal to 40*15000=600000 years!
An earth ship (with the current level of technology) will fly to the star TRAPPIST-1 in about 600 thousand years! Homo sapiens exists on Earth (according to scientists) only 35-40 thousand years, and here as much as 600 thousand years!
In the near future, technology will not allow a person to reach the star TRAPPIST-1. Even promising engines (ion, photon, space sails, etc.), which are not in earthly reality, can be estimated to accelerate the ship to a speed of 10,000 km / s, 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 flying with the help of suspended animation or for several generations of migrants, 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 path from end to end for a modern earthly ship will be 1.5 billion years! Science suggests that our Earth is 4.5 billion years old, and multicellular life is about 2 billion years old. The distance to the nearest galaxy to us - the Andromeda Nebula - is 2.5 million light years from Earth - what monstrous distances!
As you can see, of all people living today, no one will ever set foot on the earth of a planet near another star.
Despite the fact that its name is similar to the time period of the year, the year does not measure time at all, but distance. This unit is designed to measure huge.
A light year is a non-systemic unit of length. This is the distance that light travels in a vacuum in one year (365.25 days or 31,557,600 seconds).
The comparison of a light year with a calendar year began to be used after 1984. Before that, a light year is the distance traveled by light in one tropical year.
The length of the tropical year does not have an exact value, since its calculations are related to angular velocity Sun, and for it there are variations. For a light year, an average value was taken.
The difference in calculation between a tropical light year and a Julian light year is 0.02 percent. And since this unit is not used for high-precision measurements, there is no practical difference between them.
The light year as a length is used in popular science literature. In astronomy, there is another non-systemic unit for measuring long distances- parsec. The calculation of the parsec is based on the average radius of the earth's orbit. 1 parsec is equal to 3.2616 light years.
Calculations and distances
The calculation of a light year is directly related to the speed of light. For calculations in physics, it is usually taken to be 300,000,000 m/s. The exact value of the speed of light is 299,792,458 m/s. That is, 299,792,458 meters is just one light second!
The distance to the moon is approximately 384,400,000 meters, which means that the light beam will reach the surface of the moon in approximately 1.28 seconds.
The distance from the Sun to the Earth is 149,600,000,000. Therefore, a sunbeam hits the Earth in a little less than 7 minutes.
So, there are 31,557,600 seconds in a year. Multiplying this number by a distance equal to one light second, we get that one light year is equal to 9,460,730,472,580,800 meters.
1 million light years, respectively, will be equal to 9,460,730,472,580,800,000,000 meters.
According to approximate calculations of astronomers, the diameter of our galaxy is about 100,000 light years. That is, within our Galaxy there cannot be distances measured in millions of light years. Such numbers are applicable for measuring distances between galaxies.
The Andromeda galaxy closest to Earth is 2.5 million light-years away.
To date, the largest cosmic distance from Earth that can be measured is the distance to the edge of the observable universe. It is about 45 billion light years.
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.
This 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.
Often we are 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 the distance distance in vacuum without gravity fields, one effect of the Julian year (equivalent to 365.25 standard days per 86,400 SI seconds or 31,557,600 seconds) by the International Astronomical Federation,
To do this, we take 300 thousand kilometers per second (which is exactly the speed of light) and multiply with 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 the practical value of 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 a universal unit of one meter in length and a long measurement path 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 to send radio signals is completely useless.
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 refer to them and represents only the distance that light travels in one Earth year.
Anyway, in your Everyday life we measure distances: to the nearest supermarket, to the house of relatives in another city, to and so on. However, when it comes to the vast expanse of space, it turns out that the use of familiar values like kilometers is extremely irrational. And the point here is not only the difficulty of perceiving the resulting gigantic values, but the number of digits in them. Even writing so many zeros will become a problem. For example, from Mars to Earth, the most short distance- 55.7 million kilometers. Six zeros! But the red planet is one of our closest neighbors in the sky. How to use the cumbersome numbers that will be obtained when calculating the distance even to the nearest stars? And right now we need such a value as a light year. How much is he? Now let's figure it out.
The concept of a light year is also closely related to relativistic physics, in which the close connection and mutual dependence of space and time was established at the beginning of the 20th century, when the postulates of Newtonian mechanics collapsed. Before this distance value, the larger units in the system
were formed quite simply: each subsequent one was a set of units of a smaller order (centimeters, meters, kilometers, and so on). In the case of a light year, the distance was tied to time. modern science We know that the speed of light in vacuum is constant. Moreover, she is maximum speed in nature, admissible in modern relativistic physics. It was these ideas that formed the basis of the new meaning. A light year is equal to the distance that a ray of light travels in one Earth calendar year. In kilometers, this is approximately 9.46 * 10 15 kilometers. Interestingly, to the nearest moon, a photon travels the distance in 1.3 seconds. To the Sun - about eight minutes. But to the next nearest stars, Alpha, and already about four light years.
Just a fantastic distance. There is an even larger measure of space in astrophysics. A light year is about one-third of a parsec, an even larger unit of interstellar distance.
The speed of light propagation in different conditions
By the way, there is also such a feature that photons can propagate at different speeds in different environment. We already know how fast they fly in a vacuum. And when they say that a light year is equal to the distance traveled by light in a year, they mean exactly empty space. space. However, it is interesting to note that under other conditions the speed of light may be less. For example, in air, photons scatter at a slightly lower speed than in vacuum. With which one - depends on the specific state of the atmosphere. Thus, in a gas-filled medium, a light year would be somewhat smaller. However, it would not differ significantly from the accepted one.
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Light year
During the exploration of their planet, people needed various measures of measuring distances and segments. Initially, length measures were inaccurate, because different peoples had their own ways of measuring. Only in 1791, scientists from France introduced a measure that is still used today - the meter (from the Greek - "measure").
But at the beginning of the twentieth century, people began to turn their attention to the study of space. And the fact that the universe has incredible distances already exists metric system turned out to be unsuitable for measuring such large distances. It is possible to measure in kilometers the distance from our planet to the Moon or to Mars, but if you measure the distances to other planets, and even stars, then there will be an incredible number of zeros in the figure.
And then scientists decided to introduce the term "light years".
How many light years?
In just one second, photons of light cover a length of 300,000 km. A light year is the number of kilometers that light travels in 12 months. In kilometers it will be - 9,460,730,472,580.8 kilometers ≈ 9.46 1015.
Of course, using the term "light years" is more convenient than using huge kilometers. But, of course, there are approximate values:
1 light second ≈ 300 thousand kilometers.
1 light minute ≈ 18 million kilometers.
1 light hour ≈ 1,080,000,000 kilometers.
1 light day ≈ 26,000,000,000 kilometers.
1 light week ≈ 181,000,000,000 kilometers.
1 light month ≈ 790,000,000,000 kilometers.
How many?
We assume that the spacecraft flies from the third space speed(about 16.8 kilometers per second), then in 18 thousand years the ship will fly one light year. And our galaxy the Milky Way, which is about a hundred thousand light years in diameter, the ship will fly by in almost 2 billion years!
The closest star to the Sun is Proxima Centauri. It is located at a distance of about four light years. If converted to kilometers, the figure is very large.
But if we compare the distance from Proxima Centauri to the nearest galaxy, the Andromeda Nebula, then the star is very close, since Andromeda is two and a half million light years from Milky Way. The spacecraft will be able to fly there in 35 billion years.
What else are light years useful for?
Using light years helps to understand where in the universe you can try to find intelligent civilizations. So scientists determine where it makes sense to send radio signals, and where not.
How it works: the speed of light is equal to the speed of a radio signal, and it turns out that sending messages to where they will reach in thousands, or even billions of years, is completely useless. It makes sense to look for "neighbors" through the sent signal, which will go on for at least one human life.
How many earth years are there in light years?
It is a fundamentally wrong belief that this term measures time. The light year has nothing to do with Earth time and is not related to it in any way. It denotes only a measure of the distances that light travels in 1 year on Earth.
