What is one light year. How the age of the Earth was determined - description, diagram, video
Surely, having heard in some fantastic action movie the expression a la “20 to Tatooine light years”, many asked legitimate questions. I will name some of them:
Isn't a year a time?
Then what is light year?
How many kilometers does it have?
How long will it take light year spaceship With Earth?
I decided to dedicate today's article to explaining the meaning of this unit of measurement, comparing it with our usual kilometers and demonstrating the scales that 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 many as 1000. Unless, of course, he crashes in the process ...
It would seem that this is the speed! But in order to go around the whole Earth(≈ 40,000 km), our rider will need 40 times more time. And this is already 4 x 40 = 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 invent and use shorter alternative units of measurement.
Limit.
From school course physics everyone should know that the fastest rider in Universe- light. In one second, its beam covers a distance of approximately 300,000 km, and the globe, thus, it will go around in 0.134 seconds. That's 4,298,507 times faster than our virtual racer!
From Earth before Moon light reaches on average in 1.25 s, up to sun its beam will rush in a little more than 8 minutes.
Colossal, isn't it? But the existence of speeds greater than the speed of light has not yet been proven. Therefore, the scientific 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.
In this way, light year- nothing more than the distance that a ray of light overcomes in one year. On interstellar scales, using distance units smaller 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 equal to 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 = 31,536,000 seconds. Light travels 300,000 km in one second. Consequently, in a year its beam will cover a distance of 31,536,000 x 300,000 = 9,460,800,000,000 km.
This number reads like this: NINE TRILLION, FOUR HUNDRED SIXTY BILLION AND EIGHT HUNDRED MILLION kilometers.
Of course, the exact value light year slightly different from what we calculated. But when describing distances to stars in popular science articles, in principle, the highest accuracy is not needed, and a hundred or two million kilometers will not play a special role here.
Now let's continue our thought experiments...
Scales.
Let's assume modern spaceship leaves solar system with the third space velocity (≈ 16.7 km/s). The first light year he will overcome in 18,000 years!
4,36 light years to our nearest star system ( Alpha Centauri, see the image at the beginning) it will overcome in about 78 thousand years!
Our the Milky Way galaxy, having a diameter of approximately 100,000 light years, it will cross in 1 billion 780 million years.
And to the nearest one to us galaxies, spaceship rushing only after 36 billion years ...
These are the pies. But in theory, even Universe arose only 16 billion years ago ...
And finally...
You can start to wonder at the cosmic scale even without going beyond solar system because it is very large in itself. This was shown very well and clearly, for example, by the creators of the project If the Moon wereonly 1 pixel (If the moon were just one pixel): http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html .
On this I, perhaps, will complete today's article. All your questions, comments and wishes are welcome in the comments below it.
The history of the Earth is imprinted on its stones. In places like the Grand Canyon, the water that erodes its walls exposes the layers of rock from which the walls formed.
Because the old layers lie beneath the new ones, geologists can get some idea of how the earth's crust was formed. But knowing that the deeper layers are older does not tell us anything about their absolute age, that is, how old they are.
How was the age of the Earth calculated?
Scientists in the 19th century tried to calculate the age of the Earth based on the timing of the formations. rocks in modern times. But they could only guess. According to their results, the age of our planet ranges from 3 million years to 1.5 billion years. The spread is 500 times, such a result cannot, of course, be called accurate. Naturally, another way was required. Scientists wanted to find a clock that, being wound at the time of creation, would continue to run until our time. By looking at such a clock, one could accurately determine the age of the Earth.
How can you accurately calculate the age of the Earth?
And it turned out that such clocks exist: in rocks, trees and in the depths of the ocean. These natural clocks are radioactive elements that decay over time to form other elements. Determining the age of rocks or fossils using radioactive elements is called radiometric dating. Per unit time decays strictly certain part radioactive material. This fraction does not depend on the mass of the initial radioactive substance.
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Light year
During the exploration of their planet, people needed various measures measurements of 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, the already existing 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 at the third cosmic speed (about 16.8 kilometers per second), then in 18 thousand years the ship will fly by 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 traveled by light in 1 year on Earth.
Earth is the third planet from the sun. One of the largest planets in the solar system. The only planet, according to scientists, on which there is intelligent life.
It is inhabited by more than 6 billion people. And over a million other biological species.
But few scientists can answer one very simple, but incredibly complex and controversial question. How old is planet Earth?
Attempts to determine the age of our planet for many centuries have not given and do not give scientists peace.
Some say that the Earth was formed about 4.54 billion years ago through evolution. Others - call more modest figures - about 6-10 thousand years ago and tend to believe in the element of Creation! That someone (God, for example) or something created the earth.
The first, let's call them scientists-A, claim that in the distant past, the planet Earth was a small star. The star plowed the expanses of the galaxy, gradually fading away. The more it went out, the more it lost its mass and energy, falling under the influence of other cosmic bodies. So she got under the influence of the sun. And at some point, it finally disintegrated, forming a gas and dust cloud.
After some time, in place of the cloud, a planet appeared, which is now commonly called the Earth. According to scientists-A, this happened 4.5-5 billion years ago. To substantiate their theory, they cite data from two main methods of radioisotope and geological dating.
The radioisotope (or radiometric) dating method boils down to taking an object that contains any radioactive isotope (carbon-14, uranium-238, tholium-232, potassium-40) and studying the fraction of its decay. Knowing exactly the half-life of a given isotope, it is quite possible to calculate the age of the sample.
As for geological dating, everything is much simpler here. Soil, fossils and other fossils and specimens are examined.
The second investigators, the scholars B, cite arguments from the Bible in their favor.
After all, if you believe Holy Scripture, Adam (the first man) was created on the sixth day of our planet's existence. Based on the calculation that there are 24 hours in a day, taking into account the genealogy of Adam and all his descendants recorded in the fifth and eleventh chapters of Genesis, as well as the chronology of his movement, we can say with a high degree of probability that the approximate age of our Earth is about 6-10 thousand years.
In addition, there are currently more than eighty various methods, used in geochronology (the science involved in determining the age of the Earth), confirming the young, and not the billionth age of the planet.
Remarkably, geochronology is based on a very simple principle of the theory of evolution, which consists in the fact that the present is nothing but the key to knowing the past. That is, if, for example, natural phenomena such as volcanic activity, the rise and fall of land occur in the present at a certain rate - there is a high degree of probability that these same phenomena occurred at the same rate in the past.
Everything, however, turns out to be simpler than it seems at first glance. The fact is that from childhood, from the school bench, we were “hammered” with the theory of evolution with its billions of eras. It is worth noting here that there were about a thousand theories of evolution, and all of them often directly contradicted each other.
Often in countries former USSR the question of the origin of life on earth is often passed over in silence, since the received atheistic upbringing does not allow talking about the Creator. The scope of one article does not allow us to dwell even briefly on the analysis of the theory of evolution, and therefore we will focus only on a few very clear evidence that the age of our planet cannot exceed 6000 years.
Without going into the depths of physical, chemical, astronomical scientific evidence, here are 10 irrefutable facts of the youth of our planet.
1. Earth's magnetic field
It is well known that tension magnetic field The Earth falls twice in 1400 years, that is, 1400 years ago the planet's magnetic field was twice as strong as it is today, and 2800 years ago it was four times stronger than today. Based on these data, it was determined that the maximum possible age of the Earth is about 10,000 years, since then the strength of the Earth's magnetic field will be unacceptably large.
2. Meteor dust
It is known that tens of tons of meteoric dust fall on the earth, and taking this into account, it becomes clear that if the age of the earth was estimated in millions of years, then the earth would, firstly, be covered with a huge layer space dust(up to tens of meters in height), and, secondly, in earth's crust huge deposits of nickel would have been contained (as is known, meteoric dust contains up to 2.8% nickel). Today, the nickel content and the amount of meteoric dust allow us to assert that the age of the earth does not exceed 6000-7000 thousand years.
3. Soil erosion
Today it is proved that if the age of the earth exceeded several million years, then earth's surface would have been equal to sea level a long time ago.
It is known that during the decay of uranium, lead and helium nuclei are formed, which are released into the atmosphere in the amount of 300 thousand tons per year. Today it has been proven that the atmosphere contains more than 3 billion tons of helium, which means that the age of the planet does not exceed 6 thousand years.
5. Age of the Moon
When an American spacecraft was sent to the Moon, there was a serious fear that the ship could “drown” in meteoric dust, because the moon, according to the theory of evolution, was formed several billion years ago, like the Earth, which meant that this dust should be on it. it would be an incredible amount. But after the crew reached the lunar surface, it turned out that there was a very thin layer of dust on the surface of the moon, and, in addition, it turned out that the moon has a magnetic field, seismic activity and thermal radiation, in other words, its age is no more than 6000 years.
6. River deltas
Studies of river deltas show that the age of the Earth is in the range of 5,000 years.
7. Silicon in the oceans
The entry of silicon into the ocean with river water does not allow us to speak about the age of the Earth more than 8000 years.
8. Nickel in the world's oceans
The entry of nickel into the ocean with river water also indicates the youth of the planet - within the maximum limits of 9000 years.
9. Comet breakup
The study of the decay process of short period comets also suggests that the age of the Earth cannot exceed 10,000 years.
10 Radioactive Substances On The Moon
The Moon contains a fair amount of uranium-236 and thorium-230, short-lived isotopes that would not exist long ago if the Moon were billions of years old.
In fact, this list could go on and on.
- We invite you to get to know .