Sunbeam from earth to sun. How long does it take for sunlight to reach Earth

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

Light speed- how long does sunlight travel from the Sun to the Earth: a description of the Earth's orbit in the photo, the distance and place of the third planet in the Solar System.

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

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

Inside the solar core, fusion occurs, 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 in fact the light that reaches you was created tens of thousands of years ago! He managed to escape and finally got 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 take millions of years to just see their beautiful glow.

Let's look at 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.

If you know the speed with which the light "flies" and the distance from the Sun to the Earth, then it will not be difficult to calculate the time it takes it to cover such a distance.

We know the speed of light from the school physics course- about 300,000 km / s, or more precisely, 299,792,458 m / s. But an approximate value is sufficient for most calculations.

The distance from the Sun to the Earth is also known, but already from the school astronomy course - about 150 million kilometers. This distance, by the way, is taken as a standard measure of length and is called an astronomical unit. Of course, on a cosmic scale, this is a very small value, but within the solar system it is quite useful.

So, we divide the distance by the speed, and we get the "flight" time of light from the Sun to the Earth - 8 minutes and 19 seconds. Everything - just! Light travels 150 million kilometers in a matter of minutes! But this is because the distance is not too great ...

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

This is also a very interesting question. Astronomy has even introduced another unit for measuring distances - a light year. This is the distance that light travels in a vacuum - outer space, in a standard year. This distance is calculated and is equal to 9 460 730 472 580 800 meters, or more than 63 thousand astronomical units. Of course, there are other units - a light second, light minute, light hour and others - the distance that a light beam travels in a corresponding period of time. Even a light age can be counted ...

So, from the Moon to the Earth, light reaches in about 1.2 seconds. By the way, radio waves also propagate at the speed of light, so one can imagine difficulties in controlling the "Lunokhod" when the signal comes and goes with a delay. It is even more difficult to control more distant interplanetary vehicles - there delays are minutes or even hours.

From the Sun to Pluto, light reaches in 5 hours, but there is not at all the edge of the solar system. Further there is the so-called Oort cloud of many asteroids and other debris. The light “flies” to the outer edge of this cloud for a whole year and a half. But the limits of the Sun's gravitational influence are even wider - as much as one and a half light years. This is simply an incredible distance that people will not cover very soon.

By the way, the closest star to us, Proxima Centauri, is more than 4 light years away, and although it is somewhat smaller than our Sun, it is included in a multiple system of several stars, and their total mass is quite solid. This means that their gravitational influence also extends for at least 2 light years, that is, our Sun and "their Suns" interact, practically "hold hands." So much for the direct influence of the stars ...

In general, the fact that light does not spread instantly creates interesting phenomena. For example, the well-known North Star is located further from us than 400 light years. We see the light she gave off during the time of Columbus! And it's still pretty close ...

These enormous distances are practically small compared to the galactic scale. For example, light from the center of our Galaxy to us takes about 30 thousand years. And from the nearest "neighbor" - the giant Andromeda galaxy M31 - 2.5 million years. And this is from the "neighbor"!

The most gigantic formation in the Universe - the Sloan Great Wall, is a "wall" of galaxies, a huge cluster of them. This object stretches for 1.37 billion light years in length, and is located at a distance of a billion light years from us, that is, the light from it to us takes a billion years!

And finally, from the edge of the Universe, light “flies” to us for more than 13 billion years. And then there is nothing ... Or maybe there is, but this we, apparently, will never know ...