26 light years. How long is a light year in space

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 where 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 made a lot of noise in the media, it even seemed to some 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, 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. conventional orbital spaceships 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's 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.

A human-made spacecraft flies at a speed of 20 km/sec, i.e. 15,000 times slower speed Sveta. 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.

Huge outer spaces are very difficult to calculate in kilometers or miles. Scientists thought about finding other units for measuring large distances. Fans of science fiction films and books often hear about the light year. But not everyone can explain what these words mean. Some do not see its difference from the usual earthly one.

This value is popular unit of measure for cosmic distance. When defining it, use:

speed of light,
the number of seconds equal to 365 days.

An important condition for such a calculation is the absence of influence on the light of any gravitational fields. This requirement is met by a vacuum. It is in it that the speed of propagation of any electromagnetic rays remains constant.

Back in the 17th century, scientists tried to determine speed of light. Previously, astronomers assumed that the rays travel through space instantly. Galileo Galilei doubted this. He set a goal to calculate the time it takes a beam of light to travel a certain distance, equal to eight kilometers. But his experiments were unsuccessful. Research by the Danish scientist O. Römer was also unsuccessful. He noticed a temporary difference in the eclipses of the satellites of other planets, depending on the position of the Earth. When it is farther away from another space object, the rays of light need more time to reach the earth's surface. He failed to calculate their speed.

For the first time, approximately the speed of light was calculated by the Englishman James Bradley in the 18th century. This astronomer set its value at 301,000 km/s. In the last century, using Maxwell's theory of electromagnetism, scientists were able to accurately calculate the speed of a beam. The studies were carried out using the latest laser technologies, taking into account their refractive indexes. The calculated speed of light was 299,792 kilometers 458 meters per second. This helped determine a convenient unit of measure for outer space.

What is 1 light year in kilometers

365 days were taken as the basis for the calculation. If you calculate the daily value in seconds, you get 86,400 seconds. And in all these days, their number will be 31,557,600.

We calculated how far a ray of light travels per second. Multiplying this value by 31,557,600, we get a little over 9.4 trillion. It is a light year measured in kilometers. It is this distance that a light beam will travel in 365 days in a vacuum. He will make such a path, flying around the earth's orbit without the influence of gravitational fields.

Examples of some distances calculated in this way

The distance from the Earth to the Moon is covered by a ray of light in 1 minute 3 seconds;
In 100,000 such years, we can determine the diameter of our galactic disk;
The distance in light hours from the Sun to Pluto is 5.25 hours;
The beam from the earth will reach the Andromeda galaxy in 2,500,000 light years, and the star Proxima Centauri in just 4;
Sunlight reaches our planet in 8.20 minutes;
The Center of our Galaxy is located at a distance of 26 thousand light years from the Sun;
The Virgo Cluster is located at a distance of 58,000 thousand similar years from our planet;
In tens of millions of such years, clusters of galaxies are measured in diameter;
The maximum measured distance from Earth to the edge of the visible universe was 45 billion light years.

Why is he so important

The calculated speed of light enabled astronomers to determine distance between planets, stars, galaxies. It became obvious that the light emitted by a star does not reach the Earth at lightning speed. Observing space objects in the sky, we see the past. The explosion of a distant planet, which happened hundreds of years ago, scientists will record only today.

Within our universe, the use of calculations in this unit of measurement is convenient. Hours, weeks or months are used less frequently. When determining the distance to distant space objects, the resulting value will be huge. It becomes difficult and impractical to use such values in mathematical calculations. Scientists took this into account, and for astronomical calculations of large distances they use a different unit of measurement - the parsec. For complex mathematical calculations, it is more acceptable. A light year is equal to one third of a parsec.

Ratio of light years to earth years

We often measure distance in our lives: to work, the nearest store, another city. We compare different sizes together. This helps to appreciate the difference. The concepts of light years and earth years seem to many to be similar, if not the same. There is a desire to compare them. Here you must first choose what to mean by the earth year. You can define it as the distance traveled by our planet in 365 days. With these parameters, one light-like period will be equal to 63 thousand Earth years.

If the earth is calculated in days, then it will be considered a unit of time. Light indicates distance. And comparison of such values is meaningless. In this case, there is no answer to the question.

Video

This video will help you figure out what a light year is.

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In order to understand the meaning of the concept of "light year", you first need to remember the school physics course, especially the section that concerns the speed of light. So, the speed of light in vacuum, where it is not affected by various factors, such as gravitational and magnetic fields, suspended particles, refraction of a transparent medium, and so on, is 299,792.5 kilometers per second. It must be understood that in this case, light means perceived human vision.

Less well-known distance units are the light-month, week, day, hour, minute, and second.

A sufficiently long 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 Roemer in the middle of the 17th century. Of course, his data were very approximate, but the very fact of determining the final value of the speed is important. 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 travels 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 Milky Way galaxy exceeds 100,000 light years, that is, those visual observations that can be made now display a picture that existed about hundreds of thousands of 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). The average radius of the 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. An astronomical unit is approximately equal to 149.6 million kilometers.

Exploring their own planet, for hundreds of years, people have been inventing more and more new systems for measuring distance segments. In the end, it was decided to consider universal unit one meter long and big way measured 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 for 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 - accordingly, a greeting sent towards a distant galaxy will reach its goal only after millions of years. It is wiser to expect 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.

Whatever lifestyle we lead, whatever we do, one way or another, we use some units of measurement every day. We ask for a glass of water, warm up our own breakfast to a certain temperature, visually estimate how far we need to walk to the nearest post office, arrange a meeting at a certain time, and so on. All these actions require

Not just calculations, but also a certain measurement of various numerical categories: distance, quantity, weight, time, and so on. In our Everyday life we use numbers regularly. And these numbers have long been accustomed to, as if to some kind of tools. But what happens when we get out of our everyday comfort zone and face the unusual numerical values? In this article we will talk about the fantastic figures of the Universe.

universal open spaces

Even more surprising is the situation with cosmic distances. We are quite aware of the kilometers to the neighboring city and even from Moscow to New York. But it's hard to imagine distances visually when it comes to the scale of star clusters. It is now that we will need the so-called light year. After all, the distances even between neighboring stars are extremely large, and measuring them in kilometers or miles is simply irrational. And here the point is not only in the difficulty of perceiving the huge resulting numbers, but in the number of their zeros. The problem becomes to write the number. For example, the distance from Earth to Mars during the period of closest approach is 55.7 million kilometers. A value with six zeros. But Mars is one of our closest space neighbors! The distance to the nearest star, except for the Sun, will be millions of times greater. And then, if we measured it in kilometers or miles, astronomers would have to spend hours of their time just recording these gigantic quantities. The light year solved this problem. The way out was quite ingenious.

What is a light year?

Instead of inventing a new unit of measurement, which is the sum of units of a smaller order (as happens with millimeters, centimeters, meters, kilometers), it was decided to tie distance to time. Actually, the fact that time is also a physical field that affects events is more

moreover, interconnected and convertible with space, was discovered by Albert Einstein and proved through his theory of relativity. The speed of light has become a constant speed. And the passage of a light beam of a certain distance per unit of time gave new physical spatial quantities: a light second, a light minute, a light day, a light month, a light year. For example, in a second a beam of light (in space conditions - vacuum) travels a distance of about 300 thousand kilometers. It is easy to calculate that one light year is equal to approximately 9.46 * 10 15 . So, the distance from the Earth to the nearest cosmic body, the Moon, is a little more than one light second, to the Sun - about eight light minutes. The outlying bodies of the solar system, according to modern concepts, orbit at a distance of one light year. The next closest star to us, or rather, a system of double stars, Alpha and Proxima Centauri, is so far away that even the light from them reaches our telescopes only four years after its start. And after all, these are still the celestial bodies closest to us. Light from the other end of the Milky Way takes over a hundred thousand years to reach us.