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The Sun is one of the most important objects in our Universe for the existence of life on Earth. It is a star around which all the planets of our Solar System, including Earth, revolve. The Sun belongs to the G2V spectral class of stars and is located in the Milky Way Galaxy, which contains hundreds of billions of other stars. Despite not being the largest or brightest star in the Universe, it provides all the conditions for the emergence and sustenance of life on our planet.
To briefly assess the scale of our luminary, it is worth mentioning that the Sun's diameter exceeds 1.39 million kilometers, and its mass is approximately 333,000 times greater than Earth's. The energy emitted by the Sun shapes Earth's climate, participates in photosynthesis, regulates weather phenomena, and affects all forms of living organisms.
In this article, we will try to answer the most common questions about the Sun in detail, uncover amazing facts about its composition, energy sources, interaction with Earth, and the process of solar eclipses. Additionally, we will discuss the nature of solar flares, which have a noticeable impact on our planet and humanity as a whole.
What is the Sun made of?
The Sun is a massive sphere of plasma, that is, ionized gas where electrons are separated from atomic nuclei. The main components of solar matter are hydrogen and helium. According to modern estimates, hydrogen accounts for about 73.46% of the Sun's mass, and helium approximately 24.85%. Thus, all other elements combined (so-called heavy elements) make up only about 2%.
These elements primarily include oxygen (about 0.77% of the solar mass), carbon (0.29%), iron (0.16%), neon (0.12%), nitrogen (0.09%), silicon (0.07%), magnesium (0.05%), sulfur (0.04%), and a few others. Although the proportion of these substances is extremely small, their significance for the dynamics of solar plasma and the occurrence of thermonuclear reactions cannot be overstated, as even small concentrations of "heavy" elements influence the spectrum of radiation and the Sun's magnetic field characteristics.
It is interesting to note that the presence of heavy elements in the Sun is why many diverse chemical compounds exist in the Galaxy. According to modern stellar evolution theory, heavier elements are formed in the cores of large stars and during their explosions (supernovae). The Sun, in turn, inherited heavy elements from previous generations of stars, which allowed the formation of planets and, ultimately, life on one of them.
What is the source of the Sun's energy?
The primary source of the Sun's energy is thermonuclear fusion reactions in its core. Under colossal pressure and temperature (about 15 million degrees Celsius in the central regions of the Sun), hydrogen nuclei (protons) come so close that they begin to fuse into heavier nuclei, primarily helium. This process is known as the proton-proton chain reaction.
The essence of this chain is simple conceptually: four protons (hydrogen nuclei) gradually combine into one helium nucleus. At the same time, the mass of the resulting helium is slightly less than the sum of the original protons. The "lost" excess mass is converted into energy. This is what leads to the release of a colossal number of photons and, consequently, heat and light.
Most of the energy produced in the Sun's core travels millions of kilometers through various layers of the star (radiation zone, convection zone) and eventually exits into cosmic space. The journey of photons from the core to the surface can take up to hundreds of thousands of years. When they finally reach the solar photosphere, their energy has "cooled" to the Sun's surface temperature (about 5800 K) but remains sufficient to sustain life on Earth.

How great are the Sun's mass losses due to radiation?
As a result of thermonuclear reactions, the Sun loses about 4.3 million tons of matter every second. This loss is due to the fact that part of the mass during the synthesis of hydrogen into helium directly transforms into emitted energy. Over a year, the "massive" losses reach approximately 140 trillion tons, comparable to the mass of a large asteroid with a diameter of about 50 kilometers.
At first glance, these figures seem fantastic. However, given the Sun's immense size, it can afford to lose such an amount of matter for an incredibly long time. Calculations show that for the star to lose just one percent of its original mass, at the current rate of radiation, it would take about 150 billion years. This is more than ten times the estimated age of the Universe (about 13.8 billion years). Therefore, the Sun's lifespan in terms of mass losses is still very, very long.
What portion of solar radiation reaches Earth?
Less than half a billionth of the total solar radiation reaches Earth. Despite such a tiny proportion, it is this energy that determines the climatic conditions allowing the biosphere of our planet to exist. When comparing the solar heat reaching Earth with the heat emitted from Earth's interior (molten core and mantle), the latter pales in comparison, being over 25,000 times weaker.
It is important to understand that the intensity of sunlight diminishes inversely proportional to the square of the distance. Earth is approximately 150 million kilometers away from the Sun. Considering how much the radiation weakens as it travels such distances, it becomes evident how immense the Sun's overall energy output is.
Additionally, it is worth noting that Earth's circular orbit around the Sun is actually elliptical, which slightly affects the amount of sunlight received in different seasons of the year. When Earth is slightly closer to the Sun, it receives more light, and when slightly farther, less. However, the primary factor in seasonal changes on Earth is the tilt of Earth's axis, not variations in the distance to the Sun.
Interesting fact
Sunlight takes about 8 minutes and 17 seconds to reach our planet. For comparison, sunlight from the Moon to Earth takes only about 1.255 seconds.
Ultraviolet radiation from the Sun is significantly weakened by the ozone layer in the atmosphere, which is very important for protecting Earth's biosphere. The intensity of ultraviolet light on Earth's surface strongly depends on geographical latitude and the angle of sunlight. For example, at the equator, sunlight falls at a more direct angle, leading to higher levels of ultraviolet radiation.
Ultraviolet radiation from the Sun has antiseptic properties, making it useful for disinfecting water and various surfaces. It also stimulates the synthesis of vitamin D in the human body and affects skin pigmentation, producing a tan. However, excessive ultraviolet exposure can be harmful, increasing the risk of burns and skin diseases.
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How does a solar eclipse occur?
A solar eclipse occurs when the Moon passes between the Sun and an observer on Earth, completely or partially covering the solar disk. This phenomenon is only possible during the new moon phase, when the Moon is not illuminated on the side facing Earth.
However, not every new moon results in an eclipse. For an eclipse to occur, the Moon must be near one of the lunar nodes—points where the apparent orbits of the Moon and Sun intersect in the celestial sphere. If the new moon occurs within approximately 12 degrees of one of these nodes, an eclipse becomes possible.
There are several types of solar eclipses:
- Total: The observer on Earth falls into the full shadow of the Moon, and the Sun's disk is completely covered. During a total eclipse, the solar corona—the outermost layer of the Sun's atmosphere—can be observed.
- Partial: The Moon only partially covers the Sun. In this case, part of the Sun's disk remains visible.
- Annular: The Moon is farther from Earth (or the Sun is slightly closer to Earth), and its apparent diameter is smaller than the apparent diameter of the Sun's disk. The Moon cannot completely cover the Sun, leaving a bright ring around the edges.
On average, 2 to 5 solar eclipses can be observed on Earth each year, and no more than two of them are total or annular. Over a century, approximately 237 solar eclipses occur, including 160 partial, 63 total, and 14 annular. There are also rare hybrid eclipses, which can begin as annular and transition to total (or vice versa), but they occur much less frequently.

What are solar flares?
Solar flares are large-scale explosive processes occurring in the Sun's surface layers (primarily in the photosphere and chromosphere). They are closely linked to solar activity phenomena, including the appearance of sunspots and magnetic "pairs." A flare, in the literal sense of the word, manifests as a sharp local increase in brightness in a specific area of the Sun's surface.
The duration of a flare is often limited to tens of minutes, sometimes even less than a few minutes. However, during the most active phase, a colossal amount of energy is released. To put it into perspective, a major solar flare can release hundreds of times more heat than all of humanity would obtain by burning all available reserves of oil and coal on Earth.
Although the energy of a single flare is relatively small compared to the Sun's total radiation (constituting only a tiny fraction of a percent), it can lead to serious consequences for our planet:
- Increased X-ray and ultraviolet radiation: High-energy radiation can affect Earth's ionosphere, causing disruptions in radio communication and navigation systems.
- Charged particle streams: They travel from the Sun to Earth at speeds of around 1000 km/s or more. When these particles reach Earth's upper atmosphere, they cause auroras and create electromagnetic storms that can disrupt telecommunications and electronic devices.
- Examples of significant events: On September 2, 1967, a bright solar flare was recorded, leading to a global radio communication outage lasting about two hours.
In modern times, the study of solar flares and related space "weather" (solar wind, coronal mass ejections, etc.) is of practical importance. The development of satellite technologies, navigation systems (GPS, GLONASS), and power grids on Earth makes humanity especially vulnerable to surges in solar activity. Therefore, continuous monitoring of the Sun through ground-based observatories and spacecraft is one of the critical precautionary measures for timely forecasting of geomagnetic disturbances and protecting critical systems.
The Sun is not just a bright circle in the sky but a colossal thermonuclear reactor that provides the essential conditions for life on Earth. It is primarily composed of hydrogen and helium, and within its core, fusion reactions release immense streams of energy. Although the Sun loses millions of tons of mass every second, even a fraction of a percent of its total weight will suffice for a lifespan far greater than the age of the Universe.
Only a minuscule portion of sunlight reaches Earth, yet it shapes the climate and provides energy for photosynthesis, sustaining our ecosystems. An intriguing aspect of the Sun-Earth interaction is solar eclipses, which occur several times a year and visually demonstrate the movements of celestial bodies.
No less important and sometimes dangerous aspects of our star's nature are solar flares, during which vast amounts of energy are released, streams of charged particles are emitted, and intensified X-ray radiation impacts communication, electronics, and Earth's biosphere. Modern observation and research methods, including orbital telescopes and space probes, help us better understand and predict solar activity, which is crucial for technological progress and humanity's safety.
Thus, the Sun is an integral part of our lives and an inexhaustible source of energy. The more we learn about it, the more we realize its role in evolution, climate, and the existence of all life on Earth.
Learn more fascinating facts about the Sun from the following documentaries we've selected for you.
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In the video player, you can enable subtitles and choose their translation to any language in the settings.
In the video player, you can enable subtitles and choose their translation to any language in the settings.