Every day, for billions of years, the Sun rises above the horizon of the Earth. It is 150 million kilometers away from us, but shines so bright in the sky that cannot be viewed without risk of eye damage. On the Sun’s surface temperature is 5500 degrees — enough for every probe has decayed long before fly up to the surface. In short, the Sun is too hot to keep it in his fist. But this does not mean that it cannot be studied. In our galaxy more than 100 billion stars, which we also cannot miss. Thus we are able to search and find methods of their study.
Actually, there are several ingenious ways that allowed us to begin to unravel the mysteries of the stars scattered across the night sky, though they are not far from us. How is that possible?
Let’s start with the light itself. Maybe we can’t safely look at the Sun, but the scientific instruments. As you know, white light consists of all colors of the rainbow, and we can see these colors — from dark red to purple — if “Rassam” light prism.
In 1802 the English scientist William Hyde Wollaston had done this with the light of the Sun and revealed something unexpected: the dark lines in the spectrum. A few years later, the German optician Josef von Fraunhofer constructed a special instrument spectrometer for splitting the best light. And saw even more of these curious dark lines.
Soon scientists realized that dark lines appeared where the colors missing from the spectrum. They are gone, because elements in the Sun and around these absorb certain wavelengths of light. The dark line goes, indicated the presence of certain elements, hydrogen, sodium and calcium.
This is an extremely intelligent, beautiful and easy opening instantly told us about the key elements of our nearest star. But, says Philip Podsiadlowski, a physicist at Oxford University, this approach has its limitations. “He can tell only about the composition of the surface, but won’t say anything about the composition of the Sun,” he says.
What is inside the Sun and whether its content is to explain the enormous energy of our luminaries?
Our understanding of the massive energy output of the Sun began to crystallize in the early 20th century, when they suggested that if hydrogen atoms can fuse together, they will create an entirely new element — helium — and releasing energy in the process. It became obvious that the Sun is rich in hydrogen and helium takes its first power transition in the past. However, this idea had yet to confirm.
“In the 1930s, people realized that the Sun probably feeds on the energy of fusion of hydrogen, but until now it has remained purely a theory,” explains Podsiadlowski.
And then the study of the Sun was indeed strange. To better understand the star that gives life to our planet, we had to go underground. We had to arrange our experiments under the mountains. It was designed by a Japanese detector Super-Kamiokande (Super K), among other things, which gives to the surface excellent results.
In 1000 meters below the surface is a strange dirty bathroom. It is a lake extremely clear water and 13,000 spherical objects cover the walls, floor under water and the ceiling. It is a fantastic set: Super K is so arranged that helps us to understand the principles of operation of the Sun.
Once the detector so deep, he obviously was not built to detect light. Instead, he waits for special particles that are born in the center of our star and pass through the substance, as the plane flies through the air.
You pass through the trillions of particles every second. If there was no special detectors, we would never know about it. But Super-K can detect about 40 particles per day, by detecting the special light that is born when these particles — neutrinos — interact with a pool of clean water.
Created light is incredibly weak, but generates a sort of halo around neutrinos, and this halo can catch a phenomenally sensitive detectors of light in abundance on the walls.
Special types of neutrinos, which are determined using this method are a direct Testament to the fact that inside the Sun is nuclear fusion of hydrogen into helium. We have no other explanation for the appearance of neutrinos.
“You can catch only a small fraction of the neutrino, but after you calculate how many neutrinos there should be, based on actual data,” says Podsiadlowski.
What is even more amazing: these neutrinos are formed during the fusion reactions in the center of the Sun, and within eight minutes their catches detector of Super-K. the Study of neutrinos allows us to observe what is happening deep in the bowels of the Sun almost in real time.
If that’s not enough, we can even depict the Sun with this method. It is possible to create images of the interior of the Sun solely from measurements made in the underground, where no can enter the sunlight.
To better understand the details of these synthesis reactions, it is also necessary to try to recreate them on Earth. In principle, it is not difficult. 13-year-old British schoolboy successfully initiated a fusion reaction in 2014. But if you want to observe these reactions without interference of the particles with a whistle coming from the Sun, would have to sink into the ground.
This is Marie-Louise Aliotta, a nuclear physicist from the University of Edinburgh.
What is particularly difficult in the reactions of synthesis, explains Aliotta is to “force” the two atoms to agree to the merger. The likelihood of this, despite trillions of atoms floating everywhere, is negligible.
But the Sun has two advantages that tip the bowl in favor of synthesis. It is massive, so it has a huge number of atoms, and it is also a powerful gravity, which compresses the hydrogen in the plasma: gaseous hydrogen is under such intense pressure that the electrons are separated from protons in the nucleus. In this environment, the synthesis reaction occurs with pleasure.
“In the star type of the Sun is the probability that in the process of nuclear reactions will be released a significant amount of energy, quite high simply because there are many protons, explains Liotta. — In the laboratory we do not have such a number of protons, so it is much more difficult to study such processes”.
However, Aliotta able to experiment with fusion in places like the Laboratory for underground nuclear astrophysics (LUNA) in Italy. This work allows Aliotti and her colleagues to learn more about how synthesis — what products are thus born, as interacting particles.
Easy to get the impression that the Sun is a constant feature, which will Shine with an enviable level of consistency forever. But it’s not. Actually, the stars have cycles and lifespan, which depends on their size and exact proportions of the elements within them and can be very different.
In recent years, we were able to learn more about how the Sun changes by studying some of its features. Spot, for example, is temporary dark areas that appear on the Sun’s surface from time to time. The probes had the opportunity to learn exactly how a lot of radiation, including visible light, is radiated by the Sun in a few years.
In the 1980s, scientists working on the mission Solar Maximum Mission, realized that within 10 years the energy output of the Sun decreased and then again increased. But what really surprised them is the number of sunspots corresponding to this activity: the more she had, the more energy released the Sun. Since the spots are darker and colder than the rest of the solar surface, it was a surprise.
“Everything was the opposite, says Simon foster from Imperial College in London. — It was very strange that the more dark and cold features, the Sun hot”.
In the end, the scientists found the cause of this. On the surface of the Sun there are special bright areas — the torches — which coincide with sunspots, but differ from them so noticeable and and those those. These flares release more energy.
Along with stains, can also detect solar flares — powerful bursts of matter escaping from the surface of the Sun after building up magnetic energy. Because stars emit radiation across the electromagnetic spectrum, these flashes can be detected by x-ray detectors. But there are other ways. For example, listening to radio — other form of electromagnetic radiation.
The huge Jodrell Bank radio telescope in England, the first of its kind, able to detect solar flares, says Tim O’brien of the University of Manchester, working on the telescope.
Radio telescopes very well highlight interesting moments in the life of a star. When the star is behaving “normally”, without showing too much activity, it will not emit lots of radio waves. But when stars are born, when they die, you receive a lot of radio waves.
“We see active event. We see the explosions of stars, shock waves, stellar winds,” says O’brien.
Radio telescopes have also been used scientists of Northern Ireland by Jocelyn bell Burnell the discovery of pulsars — a special type of neutron stars.
Neutron stars are born after a giant supernova explosions, when a star collapses in on itself and becomes incredibly dense. Pulsars are examples of such neutron stars that emit beams of electromagnetic radiation from the poles and can be detected by radio telescopes.
Due to the regular signals emitted every few milliseconds, some scientists at first it was thought that this form of communication intelligent species throughout the Universe.
Thanks to the discovery of many pulsars, it is now clear that regular pulse generated by rotation of the star itself.
“It rotates around a vertical axis, and this beam goes diagonally — as if sweeping the sky, explains O’brien. — If he goes to the line of sight, you will see regular flashes with the rotation of the beam. As at the lighthouse”.
Some stars are doomed to become pulsars. But our Sun will not suffer such a fate: it’s too small to explode in a supernova reaction in the end of his life. What will be his fate after billions of years?
From observations of other stars around us in the galaxy we know that there are a number of possible solutions. But given the mass of our Sun and comparing it with similar stars, we decided that the future of our star is obvious enough.
We expect that it will gradually expand as we age in the next 5 billion years — to become a red giant. The radiation will become progressively weaker as the consumption of hydrogen fuel. In a “weak” light will be lower frequency, lower energy, and the Sun, therefore, be overlooked.
Then, after a series of explosions, all that remains, it will be the internal carbon core of the Sun is a diamond the size of Earth. This white dwarf will slowly cool down over a trillion years.
We still very much do not know about the Sun, and a number of projects intended to resolve long-standing concern of scientists riddles.
For example, Solar Probe Plus will approach the Sun closer than any other probe in history to try to learn more about how solar winds are made, and to understand why the Sun’s corona is an aura of plasma around the sun is hotter than its actual surface.
But the basics are known to us. Splitting the sunlight into the colour spectrum, catching neutrinos in the deep dark underground labs, we were able to answer many important questions about the nature of our Sun. We also know a lot about what are the stars produce light and how this process has produced a wide range of elements needed on Earth.