How long does light travel to Mars from the earth and the sun? How long does it take for sunlight to reach Earth? Passage of light from the sun to the earth

Many people think that the central star of our galaxy simply shines and its rays spread instantly, but this is not so. How to calculate how long it takes light to travel from the Sun to the Earth, why this value will be different at different times of the year - facts that will be of interest not only to children, but also to adults.

How does the sun shine

Sunlight, which warms all life on Earth with its rays, is the result of complex chemical reactions. The sun is a big hot ball. It has several layers of hydrogen and helium hundreds of thousands of kilometers thick. The temperature on the surface of the star is 6000 Kelvin or 5726.85°C. At the core, where sunlight is born, this figure is much higher - 15 million °K.

At this temperature and pressure, the thermonuclear fusion reaction inside the nucleus continuously occurs: 4 hydrogen atoms merge into a helium nucleus. This is repeated an infinite number of times. In one second, as a result of this synthesis, 600 million tons of hydrogen become helium. And every 70 thousand years the sun converts hydrogen in an amount equal to the mass of the Earth.

Nuclear fusion releases large amounts of energy in the form of photons—massless particles that exist only by traveling at the speed of light. During its life, a photon is emitted and absorbed millions of times by gas molecules.

Interesting fact: it takes a photon 200 thousand years to get from the core of the Sun to the surface.

How long does light travel from the Sun to the Earth?

To calculate the time it takes for a beam of light to reach the Earth, you need to know the distance between our planet and the star, as well as the speed of light. The first attempts to calculate the path that an infinite number of photons travel every day were made at the end of the 17th century. Scientists of that time obtained a figure of 139 million km, but it was inaccurate.

Later, more accurate calculations were made, according to which the distance from the Sun to the Earth is 150 million km. Although this value is taken as a constant and is called an astronomical unit, our planet moves along an elongated elliptical orbit, so the distance between two celestial bodies changes. In January it decreases to 147 million km (perihelion), and in July the mileage is maximum - 152 million km (aphelion).

In 1975, the exact speed of photons in vacuum was established as 299,792,458 m/s, but most calculations use its approximate value of 300 thousand km/s.

The time required for the sun's rays to travel the distance to the Earth at different segments of our planet's orbit is given in the table below:

Thus, at any time of the year, sunlight reaches the Earth in 8 minutes and 3-25 seconds. If the Sun suddenly went out, the earthlings would know it after the specified time.

Interesting: solar radiation can penetrate 85 meters deep into the ocean, and when passing through various substances, it can slow down or be refracted, focusing at one point.

How long does it take for light to reach Earth from other objects?

To determine the distance between various objects in space, astronomy uses a value such as a light year. This indicator is equal to the path that light travels in outer space in a standard Earth year. In quantitative terms, a light year is 9,460,730,472,580,800 m or more than 63 thousand astronomical units.

The time it takes photons of sunlight to travel to the following objects in the universe will be equal to:

• for the planet Pluto, the farthest from the Sun, photons are 5 hours;
• for the farthest point of our system, the cloud of asteroids and Oort debris - as much as 1.5 years;
• for the bright star closest to Earth, Proxima Centauri, it is 4 years.

Light travels the distance between the Moon and the Earth in 1.2 seconds, and radio waves travel at the same speed. This creates difficulties in controlling spacecraft (for example, the Lunokhod), since the signal arrives and leaves with a delay.

Light does not travel instantly. This is the reason that many cosmic phenomena can be observed with a long delay. Thus, the bright Polaris is located 400 light years from Earth. Its rays, which can be observed now, were sent back in the time of Columbus.

> > > How long does it take for sunlight to reach Earth?

Speed ​​of light- how long does it take sunlight to travel from the Sun to the Earth: description of the Earth’s orbit in the photo, distance and place of the third planet in the Solar System.

It seems strange because everyone thinks that the Sun just shines and everything happens as if instantly. The sun's rays travel towards us at the speed of light and move in a vacuum environment. In short, the entire journey takes 8 minutes and 20 seconds. Yes, the irony is that if our star suddenly goes somewhere, it will only reach us in 8 minutes.

Understanding the speed of light is important in astronomy, so let's turn to mathematics. The distance from the Earth to the Sun is 150 million km, and the speed of light is 300,000 km/s. Divide and get the specified time. But this is an average.

Let's also remember that our planet rotates along an elliptical orbital path and the distance changes by 147-152 million km. Then at maximum approach the speed will be 490 seconds, and at a distance – 507 seconds. But then it gets even more interesting.

Fusion occurs inside the solar core, resulting in the formation of photons. It all starts in the form of gamma rays, which are absorbed many times by the star, travel inside it and only then break through to the surface. But the most amazing thing is that the actual light that reaches you was created tens of thousands of years ago! He managed to break free and finally get to you in 8 minutes.

Yes, when you look into space, you literally see traces of the past everywhere. The reflected moonlight moves towards us for a second. But Alpha Centauri takes more than 4 years. Now think about the stars in other galaxies that spend millions of years just for us to see their beautiful glow.

Let's look from the other side. If there are intelligent aliens who are now looking at our planet, they will only see dinosaurs. This is why the speed of light is important to scientists and cosmologists.

This fiery sphere is too bright for the naked eye. But if you look deeper into it, you can see the true nature of the Sun. This giant ball of hot gas is the largest object in the solar system. The sun produces heat and light. It is the source of energy for life on Earth. Deep in the bowels of the Sun it happens all the time nuclear reaction. Our star is dangerous, but we cannot live without it. No aspect of life would continue without the Sun.

Light is one of the fundamental components of our universe, a fundamental part of everything that exists. This phenomenon is not only the most important, but also the fastest in space. The speed of light reaches 300,000 km/s. Since the distance to the Sun is about 150 million km, then light reaches Earth in about 8 minutes. But these 8 minutes are just the final throw in his journey. It will take about a million years before light escapes the harsh interior of the Sun. This means that the light that people see on Earth now was produced long before human civilization appeared.

The sun has several layers of heavy gas hundreds of thousands of kilometers thick. And in its center there is a core that gives birth to sunlight. And it gives birth to one of the most destructive reactions in the universe - nuclear fusion (converting hydrogen to helium). If you combine two hydrogen atoms, a reaction occurs and you get helium. It sounds simple, but it's not. In fact, it is not easy to connect two atoms because the two protons have the same positive charge and therefore repel each other. Protons don't like to get close to each other. It takes a lot of energy to merge them, and this happens very rarely. Blending protons involves the enormous amounts of heat and pressure that gravity produces.

The sun contains about 99.8% of the matter in the entire solar system, and all this mass holds the layers of the Sun together with the help of a powerful gravitational force. Gravity helps the hydrogen atoms combine and this is how nuclear fusion occurs. In this nuclear reactor, hydrogen atoms combine an “infinite” number of times per second. Some collisions are so strong that the atoms fuse, releasing energy. But surprisingly, she is incredibly weak. During fusion, less than 1% of protons are converted into energy, which is not enough even for a car engine. And this energy is created only by synthesis. Most protons are not synthesized when they collide. This allows the Sun to live for another 10 billion years.

Path the smallest particle of light - a photon, begins in the hot core of the Sun. Having originated in the form of a gamma ray, a photon flies out of the solar core at the speed of light. If there were no obstacles for him, at such a speed he would pierce the surface of the Sun in 2 seconds. The sun is so dense that in order to break through its layers of various gases to the outside, the ray requires 100 thousand, if not millions of years. After leaving the solar core, the newborn photon makes its way through a thick layer of hydrogen atoms. The thickness of this layer is more than 600 thousand km. It will take a photon 100 years to overcome it. After this, a breakthrough begins through the plasma of the Sun, which stretches for 320 thousand km. It has an electrical charge that prevents the movement of photons. Its particles hold the photon for a split second, then release it and it collides with other plasma particles. All these processes last for thousands and even millions of years, until finally the photon breaks out and continues its path to the Earth or other corners of the universe.

How long does it take for sunlight to reach Earth? Obviously, sunlight travels at the speed of light. Photons emitted from the surface of the Sun take some time to travel through the vacuum of space and reach our eyes. On average, sunlight travels the distance from the Sun to the Earth in 8 minutes and 20 seconds. If the Sun suddenly disappeared from our Universe, you would have a little over 8 minutes before you noticed something was wrong.

How do you get these 8 minutes 20 seconds? We orbit the Sun at a distance of about 150 million kilometers. Light travels at a speed of 300,000 kilometers per second. Dividing one by the other, we get 500 seconds, or 8 minutes and 20 seconds. The resulting time is an average because the Earth moves in an elliptical orbit around the Sun. The shortest distance is 147 million kilometers and the longest is 152 million kilometers. At the closest point, light takes 490 seconds to reach the Earth, while at the most distant point, light takes 507 seconds.

Things get much more interesting when we consider the journey of photons inside the Sun. You probably know that photons are produced by thermonuclear reactions inside the Sun's core. These photons are emitted and absorbed in the star's radiative zone countless times before they finally reach the surface. After all, the photons that hit your eyes were actually created tens of thousands of years ago. So the journey to Earth, which takes just over 8 minutes, is only a moment in the life of a photon.

From all this, it becomes clear that when looking into space you are looking into the past. Light from our closest star, Alpha Centauri, takes about 4 years to reach us, so when we look at this star, we are actually seeing what it looked like 4 years ago. But there are galaxies located millions of light years away from us. If suddenly in one of these galaxies there is a civilization with highly developed technologies, then they may even observe dinosaurs roaming the surface of our planet.

Information about our immediate cosmic environment is becoming publicly available: ordinary users can, without leaving home, calculate the distances to neighboring planets and the travel time to them. If you are interested in the question of the distance of Mars from the Sun, it is worth familiarizing yourself with the basics of measuring cosmic distances.

How is the distance to stars measured and what is a light year?

Units of distances in space are special, derived from the international system of measurement in a separate column.
A.e. is a measure of distance in astronomy, showing the distance of the average location of the third planet - the Earth - from the Sun.

A.e.– a unit of measurement of distances in astronomy, equal to 149,597,870 km

You can also call this unit the radius of the orbit of our planet.

AE is the distance between the centers of the Earth and its orbit

In astronomical units, you can measure distances between objects within the same star system, like the Solar one. For the scale of the Universe, a.u. - a very small unit. Therefore, the distance between stars and galaxies is expressed in light years.

In physics, light has long been the standard for the fastest phenomenon in the world, but on a cosmic, incomprehensible scale, even light does not move instantly. On the way from one corner of the Universe to another, light slows down, scatters, changes its spectrum, and encounters material obstacles.

Light year- this is the stellar distance that light manages to travel 9,460,730,472,580,800 km in one earthly year

The distance of one light year is equal to the speed of light multiplied by one Earth year. The Julian year must be converted to seconds before multiplying, since the speed of light is also expressed in seconds.

Julian year(a) - a unit of time in astronomy equal to 365.25 Julian days

Relying on astronomical units can perform more complex calculations.

Light speed

What is meant by visible light rays is a stream of non-atomic particle photons, the name of which comes from the Greek term "photos" - "light".
For an earthling, one light year is an insurmountably long distance. The average person, under the conditions of Earth's gravity, can reach a speed of about 20 km/h on his own. Photons travel 60 million times faster and travel 300 thousand kilometers every second. This is the maximum speed achieved by visible light in a vacuum.

Speed ​​of light in vacuum equals 299,792,458 m/s

In the resistance of the air or water environment, for example, in the atmosphere or oceans of the Earth, respectively, light loses speed by no more than 25% and travels 225 thousand km per second.
From these data follow all other calculations that allow us to assess the possibility of flights throughout the solar system and between stars. In one minute, light travels 18 million kilometers of space.
The closer a person gets to technological progress reaching the speed of light, the less time will need to be spent on space travel.

How many light years to Mars

We have long known how to overcome enormous distances from practical examples.

How long it takes for earthling astronauts to fly to the red planet is an equation with a variable value, because our planet and Mars are constantly in motion. Each planet is in its own orbit around the Sun. The planets can approach each other or be on opposite sides of the star at extreme distances.
Of course, the most economical solution for earthlings would be to fly to Mars when the planets are at a minimum distance.

The distance that light travels in one year is 9460.73 billion kilometers. The minimum possible distance between Earth and Mars is 54.55 million km.

0.0000057 light years from Earth to Mars

Having such data, we can conclude that the minimum distance between two planets is equal to 181 light seconds, or 3 light minutes. In other words, there are 0.00000570776255707763 light years between Mars and Earth.

How long does it take light to get to Mars?

Despite its physical inaccessibility, it is possible to accurately calculate how long on average it takes starlight to travel from the Sun to Mars.
A flight to Mars from the central star of the solar system can be accomplished by a photon - a light particle - without taking into account obstacles and interference in 12.01 minutes. Calculations are obtained from the constant speed of light in a vacuum - 300 thousand kilometers per second - and the average distance of the red planet from the star, equal to 228 million km.
228,000 thousand km / 300 thousand km/s = 760 s = 12 minutes 1 second - the time required to fly from the Sun to Mars or back at the speed of light. The distance when Mars is at aphelion the light will travel in 13.01 minutes, at perihelion in 11 minutes.

How long does it take to fly to Mars at the speed of light?

The time for a hypothetical flight to Mars is easy to calculate based on the above knowledge. There is a precisely calculated flight path, capabilities and minimum distance from Earth to Mars. It is over 54 million km, which is 3 minutes for the luminous flux. Only if you move at the speed of light, flying to Mars will take not just countless months, but almost moments. Three minutes between Mars and Earth at the speed of light is difficult to compare with any terrestrial transport.

The Red Planet will be within reach if humanity advances to travel at the speed of light. With the current pace of scientific development, the discovery of new futuristic modes of transport is only a matter of time.