The time it takes for sunlight to reach the earth. How long does it take for sunlight to reach the ground?
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Amazing Universe
2014-04-14 | Text: Alexey Kirillov | Photo ©: from the site http://commons.wikimedia.org/ | 14588
For Cosmonautics Day, we have made a selection of amazing facts about space that are difficult to fit in your mind.
1.
Once upon a time the Earth seemed huge to man. It took Fernando Magellan (1480-1521) the first ever round the world trip for 3 years. The steam engine "made" the Earth smaller: in 1889, a journalist for the newspaper "World ”22-year-old Nellie Bly circled the globe in 72 days - she repeated the path taken by Vileas Fogg, wanting to prove that the famous novel by Jules Verne is not fiction at all. Reactive technologies "turned" the planet into a very small ball. A liner flying at a cruising speed of 900 km / h will take less than two days to go around the Earth. Well, the Vostok-1 spacecraft with the world's first cosmonaut on board made a revolution around the planet in just 108 minutes.
But the true dimensions of the Earth can only be understood in comparison with other space objects. To fly around Jupiter (1 thousand 320 planets the size of the Earth will fit inside this giant), the same liner will take 21 days to fly around the Sun - more than six months.
But what is six months compared to 1100 years? This is exactly how much it will take to fly around the largest of the stars known to date - VY Big Dog... During this time, 35 generations of people will be replaced on Earth. If the Earth is represented as a sphere with a diameter of one centimeter, then with a similar ratio the diameter VY will be 2.3 km! Think about it: if VY Canis Major is placed in the place of the Sun, then the surface of the star will be near Saturn, completely absorbing the orbits of not only Mercury, Venus and Earth, but even Mars and Jupiter.
2. There are 400 billion stars in our galaxy. How big is this figure? Judge for yourself: if suddenly you want to count all the stars of the Milky Way like this: one, two, three, four and so on, spending 1 second on each star, you will need ... 12 thousand years !!! But at the moment, scientists know about 1 million 600 thousand galaxies!
3.
Space is a real time machine. This is due to the fact that we do not see the objects themselves, but the light reflected or emitted by them. Is always. Even the text you are reading now, you see a little in the past. Light from the Sun reaches us in 8 minutes, so we always see the Sun as it was 8 minutes ago. But, for example, the North Star is located 434 light years from us. Maybe this star has not existed for 200 years, but we can still see it! The most distant space object in the past is the galaxy z8_GND_5296. We see it as it was 13.5 billion years ago, that is, at the time when Solar system did not even exist yet (the age of the solar system is "only" 4.5 billion years).
4.
The sunlight that we see every day is 30 thousand years old. The energy that we receive from the Sun was formed in its core 30,000 years ago - this is how long it takes for photons (light particles) to “break through” from the center of the sun to its surface. After that, they reach Earth in just 8 minutes. The temperature of the solar core is more than 13 million degrees, and all the energy it generates must first pass through numerous layers to the surface in the form of light of other radiations.
5.
The closest star to us, apart from the Sun, is Proxima Centauri. The distance to it is 4.24 light years. You can fly to Proxima on our beloved liner in just 5 million years. If humanity, having just appeared 2 million years ago, would immediately go to Proxima using an airplane, by now it would not have overcome even half of this path!
By the way, the diameter of the galaxy " Milky Way", On the outskirts of which our solar system is located, is 100 thousand light years. The largest galaxies known to date, IC 1101, is 20 times larger at 2 million light years. As for the entire universe, its size is estimated at 156 billion light years. Try to calculate how long it will take to cover this distance by plane!
6.
One of the favorite arguments of opponents of the theory of the spread of life throughout the Universe is as follows: the Earth is a source of radio wave pollution, and if there were intelligent beings on other planets, they would certainly notice it and get in touch. But it's not that simple. A radio signal cannot travel faster than the speed of light. If we assume that life is indeed a very widespread phenomenon (in every galaxy there is at least one "living planet"), then the radio signal will take 2.5 million years to reach the nearest galaxy - the Andromeda Nebula! But the radio was invented by Alexander Popov only 120 years ago!
7.
The fastest man-made spacecraft is the Voyager 1 automatic probe. Its current speed is 17 km / s (61,200 km / h) - 68 times that of our aircraft. Launched in 1977, by April 2014 it had covered 19.058 billion km, or 0.002015 light years, the distance covered by a beam of light in 17 hours 36 minutes. In about 40,000 years, the device will be 1 light-year from the solar system, and in 285,000 years it may reach Sirius, located 8.6 light-years from Earth.
Scientists believe that if Voyager does not collide with a meteorite or is not absorbed by the gravity of some star, then in open space it will be able to exist for many millions of years, quite possibly, having outlived the entire human civilization that created it.
8. Although it seems to us that the Earth is at rest, it is not. With a speed of 1 thousand 674 km / h, it rotates around its axis and at a speed of 107 thousand 280 km / h (29.8 km / s) - around the Sun. In addition, the solar system orbits around the center of the galaxy at a speed of 830 thousand km / h (230 km / s), and the galaxy itself flies in space at a speed of 2 million km / h (552 km / s). If the planes moved at the same speed, the journey from St. Petersburg to Moscow would take just over one second.
9.
The most heavy substance that most of us held in our hands is lead, the favorite metal of anglers. But much heavier weights would have turned out from the substance of which they are composed neutron stars... If you fill a teaspoon with this substance, then its weight will be 110 million tons - the same as 20 Cheops pyramids! If this substance were on the surface of the Earth, it, under the influence of gravity, would break through its shell and rush to the core.
10. An area of the sun's surface the size of a matchbox shines with the same energy as three million candles. But this is nothing compared to the gigantic amount of energy that accompanies a supernova explosion. In the first 10 seconds, an exploding supernova produces more energy than the Sun in 10 billion years, and in a short period of time produces more energy than all objects in the galaxy combined (excluding other exploding supernovae). The brightness of such stars easily overshadows the luminosity of the galaxies in which they flashed.
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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 a 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. The 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 from us is at a distance of a billion light years, 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 ...
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Potentially dangerous carbon-silicon asteroid YU55, which regularly crosses the orbit of our planet. It was first discovered in December 2005. He passed at a distance of 325 thousand km from the Earth. The movement of an asteroid in the sky (observation through a telescope, New Mexico) Parameters: Diameter - about 400 meters. Weight - about 55,000,000 tons. The speed is about 17 km / sec. 2005 YU55 crosses the orbit of the Earth and the Moon in November 2005 Hypothetical consequences of the collision: ...
Any person, young and old, knows that the Sun is a star that is located in the center of our system, which is called the Solar system. The sun is the largest object in the planetary system, around which all other objects revolve. The mass of the sun is 99.866% of the total mass of the entire solar system as a whole. White point = Earth (indicated by an arrow) How many times is the mass of the Sun greater than the mass of the planet Earth? Let's count. Weight…
Quite an interesting question, from which follows the second, no less interesting - how scientists managed to measure the mass of our planet. However, let's go in order. The first scientist who managed to calculate the weight of the globe was called Nevil Makelin. This remarkable man was able to calculate the mass of our home planet already in 1774, and - very accurately. As a result of calculations, the Scotsman came to the conclusion that the weight of the planet Earth is 5,879,000,000,000,000 ...