Our solar system is made up of one main star, which is known as the sun. It is thanks to the sun that planet Earth can have enough energy in the form of light and heat. Many people do not know well what is the sun Actually, it is a star that is responsible for the different weather conditions, ocean currents and seasons of the year. It is the star that is responsible for the conditions of life on our planet.
For this reason, we are going to dedicate this article to explaining what the sun is, what its characteristics are and what functions it performs both in the universe and on our planet.
What is the sun
The first thing to understand is what the sun is and where it comes from. The sun is the most important celestial body for the existence of life on Earth. It was formed about 4.600 billion years ago from a molecular cloud of gas and dust. This material began to clump together under the action of gravity, a force that attracted more and more matter, which increased the temperature.
At one point, the temperature reached nearly a million degrees Celsius, triggering the fusion of hydrogen into helium, a nuclear reaction that releases enormous amounts of energy in the form of light and heat. This reaction is what keeps the sun stable and functioning as a G2V-type yellow dwarf star.
Unlike other stars, the sun is relatively small, but its influence is key to life on Earth. Without its energy, our planet would be a cold and lifeless place. Although humans cannot observe the sun directly, numerous instruments such as telescopes and satellites have been developed to study it. With these, scientists have been able to determine its structure, composition, and life cycle. They have also discovered that the sun is responsible for many atmospheric and spatial phenomena such as solar wind and solar storms.
Sun characteristics
The Sun is one of the closest stars to Earth, located at a distance of about 150 million kilometers. Although there are other larger and brighter stars, the Sun is a key star within our galaxy, the Milky Way. Below we detail the main characteristics of the Sun:
- Size: The sun has a radius of 695.500 kilometres, which is 109 times the size of the Earth. If it were a hollow sphere, more than 1.300.000 planets like our own could fit inside.
- Composition: It is mainly composed of hydrogen (74% of its mass) and helium (24%), although it also contains traces of heavier elements such as oxygen, carbon and iron.
- Temperature: The surface of the Sun has a temperature of approximately 5.500 degrees Celsius. However, at its core, where nuclear fusion reactions take place, the temperature can reach 15 million degrees Celsius.
- Brightness: The energy released by the sun is immense. Every second, it converts about 620 million tons of hydrogen into helium, releasing an amount of energy equivalent to 3,8 x 10^26 watts, enough to power the Earth's energy needs for millions of years.
In addition to these characteristics, the sun has an activity cycle that lasts about 11 years, during which periods of high and low activity alternate. During times of maximum activity, more sunspots and flares occur that can affect the Earth with phenomena such as the northern lights and geomagnetic storms.
Internal structure of the sun
The Sun is a gaseous sphere in constant motion. Although it does not have a solid surface like rocky planets, scientists have been able to identify several layers in its internal composition, each with distinct characteristics. These are:
- Core: It is the innermost part of the Sun, where nuclear fusion reactions take place, generating all the star's energy. The core occupies approximately 25% of the Sun's radius and has the highest temperature, around 15 million degrees Celsius.
- Radiant zone: As energy is released in the core, it propagates outward through this region. In the radiant zone, energy is transferred primarily through radiation, causing particles to continuously absorb and re-emit photons. The temperature here gradually decreases from 7 million degrees to 2 million degrees.
- Convective zone: This layer begins about 200.000 kilometres below the Sun's surface. Here, energy is transferred by convection currents, in which hot plasma rises, cools and sinks again. This process is responsible for sunspots and solar flares.
- Photosphere: It is the visible layer of the sun, and it is where the light that reaches the Earth comes from. At first glance it appears smooth, but through telescopes we can observe sunspots, which are colder and darker areas. The photosphere has a temperature of about 5.500 degrees Celsius.
- Chromosphere: It is a thinner layer located above the photosphere. The chromosphere has a reddish appearance that is visible during solar eclipses and its temperature varies between 6.000 and 36.000 degrees.
- Crown: It is the outermost layer of the solar atmosphere. Despite being at a great distance from the core, the corona can reach temperatures of up to 2 million degrees. Its appearance is a faint halo of gas that is observed during eclipses.
Thanks to continuous observation, it has been discovered that solar activity not only affects its own internal processes, but also its surroundings. Coronal mass ejections, solar flares and solar wind are examples of phenomena that can have repercussions on our planet, affecting communications and electrical systems.
Importance of the sun for the Earth
Without the sun, life as we know it would not be possible. Many of the natural processes that sustain life on Earth depend on the energy provided by the sun. Below are the main ways in which the sun influences our planet:
- Power source: The sun is the main source of energy for Earth's ecosystems. Plants, through the process of photosynthesis, transform sunlight into chemical energy that feeds herbivores, which in turn are consumed by carnivores. In this way, the sun sustains almost all food chains on the planet.
- Climate and seasons: Solar radiation is responsible for warming the Earth's surface, which gives rise to climatic phenomena and the seasons of the year. The tilt of the Earth's axis and the variation in the amount of solar radiation that falls on certain regions are the factors that explain, for example, the cold winters in the northern hemisphere and the hot summers in the southern hemisphere.
- Regulation of the water cycle: Solar radiation also drives the water cycle. Heat from the sun causes water to evaporate from oceans, rivers and lakes. This water rises into the atmosphere, cools and then returns to Earth as rain or snow, feeding bodies of water.
- Protection of the atmosphere: While the solar wind can cause phenomena such as the Northern Lights, it also plays a key role in protecting Earth's atmosphere. Earth's magnetosphere deflects solar wind particles that could otherwise erode the atmosphere and affect life on the planet.
Throughout history, the sun has been considered one of the main deities by various cultures due to its evident influence on life on Earth. Although today we understand it from a scientific point of view, it is still a key star not only for our solar system, but for the very existence of everything we know.