Solar corona: description, features, brightness and interesting facts

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:41

The sun is a huge sphere of hot gases that produce colossal energy and light and make life on Earth possible.

This celestial object is the largest and most massive in the solar system. From the Earth to it, the distance is from 150 million kilometers. It takes about eight minutes for heat and sunlight to reach us. This distance is also referred to as eight light minutes.

The star that warms our earth is made up of several outer layers such as the photosphere, chromosphere and solar corona. The outer layers of the Sun's atmosphere create energy on the surface that bubbles up and escapes from the interior of the star, defined as sunlight.

Components of the outer layer of the Sun

The layer we see is called the photosphere or sphere of light. The photosphere is marked by bright, seething granules of plasma and darker, cooler sunspots that occur when the sun's magnetic fields rip through the surface. Spots appear and move across the disk of the Sun. Observing this movement, astronomers concluded that our luminaryturns around its axis. Since the Sun does not have a solid base, different regions rotate at different speeds. Equator regions complete a full circle in about 24 days, while polar rotations can take more than 30 days (to complete a rotation).

What is the photosphere?

The photosphere is also the source of solar flares: flames that extend hundreds of thousands of miles above the Sun's surface. Solar flares produce bursts of X-ray, ultraviolet, electromagnetic radiation and radio waves. The source of X-ray and radio emission is directly from the solar corona.

What is the chromosphere?

The zone surrounding the photosphere, which is the outer shell of the Sun, is called the chromosphere. A narrow region separates the corona from the chromosphere. The temperature rises sharply in the transition region, from a few thousand degrees in the chromosphere to over a million degrees in the corona. The chromosphere emits a reddish glow, as from the combustion of superheated hydrogen. But the red rim can only be seen during an eclipse. At other times, the light from the chromosphere is generally too faint to be seen against the bright photosphere. The plasma density drops rapidly, moving upward from the chromosphere to the corona through the transition region.

What is the solar corona? Description

Astronomers are tirelessly investigating the mystery of the solar corona. What is she like?

This is the atmosphere of the Sun or its outer layer. This name was given becausethat its appearance becomes apparent when a total solar eclipse occurs. Particles from the corona extend far into space and, in fact, reach the orbit of the Earth. The shape is mainly determined by the magnetic field. Free electrons in corona motion along magnetic field lines form many different structures. The shapes seen in the corona above sunspots are often horseshoe-shaped, further confirming that they follow magnetic field lines. From the top of such "arches", long streamers can extend, at a distance of the diameter of the Sun or even more, as if some process is pulling material from the top of the arches into space. This involves the solar wind, which blows outward through our solar system. Astronomers have named such phenomena "serpentine helmet" because of their resemblance to the jagged helmets worn by knights and used by some German soldiers before 1918

What is the crown made of?

The material from which the solar corona is formed is extremely hot, consisting of rarefied plasma. The temperature inside the corona is more than a million degrees, surprisingly much higher than the temperature at the surface of the Sun, which is about 5500 °C. The pressure and density of the corona is much lower than in the Earth's atmosphere.

By observing the visible spectrum of the solar corona, bright emission lines were found at wavelengths that do not match known materials. In this regard, astronomers have suggested the existence of "coronium"as the main gas in the corona. The true nature of this phenomenon remained a mystery until it was discovered that the coronal gases were superheated above 1,000,000 °C. With such a high temperature, the two dominant elements, hydrogen and helium, are completely devoid of their electrons. Even minor substances such as carbon, nitrogen and oxygen stripped down to bare nuclei. Only the heavier constituents (iron and calcium) are able to retain some of their electrons at these temperatures. The emission from these highly ionized elements that form the spectral lines remained a mystery to early astronomers until recently.

Brightness and interesting facts

The solar surface is too bright and, as a rule, its solar atmosphere is inaccessible to our vision, the corona of the Sun is also not visible to the naked eye. The outer layer of the atmosphere is very thin and weak, so it can only be seen from the Earth at the time when a solar eclipse occurs or with a special coronagraph telescope that simulates an eclipse by covering the bright solar disk. Some coronographs use ground-based telescopes, others are carried out on satellites.

The brightness of the solar corona in X-rays is due to its enormous temperature. On the other hand, the solar photosphere emits very little X-rays. This allows the corona to be viewed across the Sun's disk as we observe it in X-rays. For this, special optics are used, which allows you to see x-rays. ATIn the early 1970s, the first US space station, Skylab, used an X-ray telescope, with which the solar corona and sunspots or holes were clearly visible for the first time. During the last decade, a huge amount of information and images on the Sun's corona has been provided. With the help of satellites, the solar corona is becoming more accessible for new and interesting observations of the Sun, its features and dynamic nature.

Sun Temperature

Although the internal structure of the solar core is hidden from direct observation, it can be deduced using various models that the maximum temperature inside our star is about 16 million degrees (Celsius). The photosphere - the visible surface of the Sun - has a temperature of about 6000 degrees Celsius, but it increases very sharply from 6000 degrees to several million degrees in the corona, in the region of 500 kilometers above the photosphere.

The sun is hotter on the inside than on the outside. However, the Sun's outer atmosphere, the corona, is indeed hotter than the photosphere.

In the late thirties, Grotrian (1939) and Edlen discovered that the strange spectral lines observed in the spectrum of the solar corona were emitted by elements such as iron (Fe), calcium (Ca) and nickel (Ni) at very high stages of ionization. They concluded that the coronal gas is very hot, with temperatures exceeding 1 million degrees.

The question of why the sun's corona is so hot remains one of astronomy's most exciting puzzles.over the past 60 years. There is no definite answer to this question yet.

Although the solar corona is disproportionately hot, it also has a very low density. Thus, only a small fraction of the total solar radiation is required to feed the corona. The total power emitted in X-rays is only about one millionth of the total luminosity of the Sun. An important question is how energy is transported to the corona and what mechanism is responsible for the transport.

Mechanisms for powering the solar corona

Several different corona power mechanisms have been proposed over the years:

• Acoustic waves.
• Fast and slow magneto-acoustic waves of bodies.
• Alfven wave bodies.
• Slow and fast magneto-acoustic surface waves.
• Current (or magnetic field) is dissipation.
• Flows of particles and magnetic flux.

These mechanisms have been tested both theoretically and experimentally and to date only acoustic waves have been ruled out.

It has not yet been studied where the upper boundary of the crown ends. The Earth and other planets of the solar system are located inside the corona. The optical radiation of the corona is observed at 10-20 solar radii (tens of millions of kilometers) and combines with the phenomenon of zodiacal light.

Magnetic Corona Solar Carpet

Recently, the "magnetic carpet" has been linked to the coronal heating puzzle.

High spatial resolution observations show that the surface of the Sun is covered with weak magnetic fields concentrated in small areas of opposite polarity (carpet magnet). These magnetic concentrations are believed to be the main points of individual magnetic tubes carrying electrical current.

Recent observations of this "magnetic carpet" show an interesting dynamic: photospheric magnetic fields are constantly moving, interacting with each other, dissipating and exiting for a very short period of time. Magnetic reconnection between a magnetic field of opposite polarity can change the topology of the field and release magnetic energy. The reconnection process will also dissipate electrical currents that convert electrical energy into heat.

This is a general idea of how the magnetic carpet might be involved in coronal heating. However, it cannot be argued that the “magnetic carpet” ultimately solves the problem of coronal heating, since a quantitative model of the process has not yet been proposed.

Can the Sun go out?

The solar system is so complex and unexplored that sensational statements such as: “The sun will soon go out” or, conversely, “The temperature of the Sun is rising and soon life on Earth will become impossible” sound ridiculous to say the least. Who can make such predictions without knowing exactly what mechanismsat the heart of this mysterious star?!