Cosmos refers to all space and time and its contents. According to science, cosmos refers to the space-time continuum, which includes all matter, energy and information. The cosm os in its large dimensions is the subject of astrophysics research. In its very small dimensions, the cosmos is studied using quantum mechanics. Meanwhile, all sciences are trying to understand its function and existence.

Modern cosmological knowledge does not allow to clearly determine the size of the entire cosmos, nor is its shape known. According to modern theories, it can be flat or curved. Most scientists assume that the cosmos is flat, but there are many different theories on the subject.The shape of the cosmos is related to the general theory of relativity, which describes space-time (that is, what the cosmos consists of) is curved under the influence of energy and mass. The cosmos also includes the Earth as well as the entire solar system.

Solar system

The celestial bodies that orbit the Sun are the planets.The Sun is a self-luminous body, that is, it has its own light and heat and is called a star. The planets of the solar system do not have their own light.They receive light and heat from the Sun, that is, they are heteroluminous bodies. Our solar system consists of 8 planets. The planets one by one are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. The outer planets: Jupiter, Saturn, Uranus and Neptune. The inner planets: Mercury, Venus, Earth and Mars. They are also rocky planets at the same time.

The sun is not a planet, but a star, i.e. a huge ball of fire around which all the planets revolve.The sun performs a spin around its axis – and, like other stars, undergoes changes. Inside the sun, a reaction takes place to convert hydrogen into helium – which is the basic nuclear reaction. The Sun’s main building block is liquid hydrogen. The sun is the center of our system, and around it the planets orbit in elliptical orbits. The Moon is also not a planet, but a satellite, i.e. a small (relatively) sphere that orbits its planet (Earth in the case of the Moon). Until 2006, the solar system had nine planets, but the International Astronomical Union stripped the ninth planet, Pluto, of its planetary status by classifying it as a dwarf planet.

The formation of the solar system

The solar system was formed about 4.6 billion years ago through a process of formation from a dense area of gas and dust cloud known as the solar nebula. This phenomenon is consistent with the current theory of star and planetary system formation, known as the protoplanetary disk theory. Here is a general description of the formation of the solar system:

1. Initial Assumptions: In a certain area of our galaxy, the Milky Way, there existed an area containing dense matter consisting mainly of hydrogen and helium, with an admixture of other elements and cosmic dust. This was the source for the future solar system.
2. The beginning of the Disruption: It is likely that a collision with another body or a shock wave from a nearby stellar explosion (supernova) caused a disturbance in the dense region of matter. This disturbance became the starting point for the formation of the solar system.
3. Condensation of the Nebula: The disturbance caused the area to start shrinking under the influence of gravity. This caused gas and dust to concentrate in the center of the nebula, creating an increasingly concentrated area.
4. Protostellar Disk: An increasingly condensed area was formed in the center of the nebula, which became the nucleus of the future Sun. Around this nucleus began to circulate a flat protoplanetary disk, made of gas, dust and particles. In this disk, future planets began to form.
5. Planetary Accretion: In the protoplanetary disk, the initial dust particles began to merge, forming larger agglomerates. These agglomerates continued to merge into larger and larger objects that were able to exert more gravitational influence and attract more matter.
6. Formation of Planets: In the process of agile formation, larger objects began to attract more and more matter until they reached a large enough mass for their gravity to form spherical bodies – planets.
7. Planet differentiation: As planets grew, thermal processes and differences in composition caused planets to differentiate into layers, such as the core, mantle and crust. This shaped their final structure and properties.
8. Formation of Other Bodies: In addition to planets, other bodies such as moons, asteroids, comets and asteroids also formed in the protoplanetary disk. Each of these objects had a unique history and influence on the formation of the solar system.
9. Formation of the System: Over time, the formation processes of planets and other bodies led to the formation of the current solar system, in which the Sun is the central star and planets, moons and other objects orbit around it.

This is a general understanding of the process of the formation of the solar system, based on observations, research and computer simulations. Details may vary depending on theoretical models and new discoveries in astronomy.

The planets of the solar system from smallest to largest in sequence

1. Mercury – diameter 4,878 km
2. Mars – diameter 6,786 km
3. Venus – diameter 12,103 km
4. Earth – diameter 12,756 km
5. Neptune – diameter 49.528 km
6. Uranus – diameter 51,118 km
7. Saturn – diameter 120,538 km
8. Jupiter – diameter 141.984 km

Mercury – the first planet from the sun

The planet was named after the Greek god Hermes, and its astronomical symbol is a circle with a cross below and a semicircle above. Mercury’s distance from the Sun is so small that it is very difficult to distinguish it clearly. Mercury is the smallest and closest planet to the Sun in our solar system. Less than 70 million kilometers from us, this planet closest to the Sun is constantly blazing with rays. Mercury’s surface is very similar to that of the Moon, and on the contrary, its interior resembles the Earth more, although its nucleus, which consists mainly of iron and nickel, is proportionally larger than that of the Earth. This nucleus accounts for 80% of Mercury’s mass and has a diameter of 3,600 kilometers. This means that Mercury’s core is larger than the entirety of the Moon, with a mantle 600 kilometers thick above it.

Without a substantial atmosphere around Mercury, there is no wind or rain, but no protection from heat or cold. At the aphelion of the south surface temperatures reach 285 degrees Celsius, while the temperature exceeds 430 degrees Celsius, which is 7.5 times more than has ever been recorded on the Earth’s surface.

Venus – the second planet from the sun

Venus is the second planet in the Solar System farther from the Sun and the brightest star we can see from Earth with the naked eye. Venus ’ size is slightly smaller than Earth’s, but its physical properties are very different, as clouds of carbon dioxide and sulfur cover it completely, and the temperature and pressure in its crust are much higher than on Earth. Because of its resemblance to Earth, it is called „Earth’s sister.” In mythology, she was the most beautiful and radiant goddess. Venus rotates slowly in the opposite direction of most planets.

Venus is one of the Earth’s planets and is located, on average, about 108,000,000 kilometers from the Sun. Its orbit is almost circular unlike other planets with elliptical orbits. One year of Venus is 0.62 Earth years and it is the closest planet to Earth. Venus has a mass of 4.87 * 108 and is the sixth mass planet in the US. Its diameter is 12,104 km, or 0.95 of the diameter of the Earth. Its surface pressure is 92 times that of Earth, and 96.5% of its atmosphere consists of carbon dioxide. Its clouds consist of sulfuric acid and, combined with carbon dioxide, maintain a strong greenhouse effect. That is, thanks to this and Aphrodite’s high pressure in its crust, it has an extremely high temperature averaging about 460 degrees Celsius. On its surface there are more than 1,600 volcanoes as well as lava mountains and plains. Its volcanoes are now inactive for 500 million years, and its tectonic plates do not move. Venus has no natural satellites or rings, and its day lasts 243 Earth days, rotates west that for this reason one of its hemispheres remains in total darkness for 58 days. Venus is believed to have no liquid core. Its volcanoes are now inactive for 500 million years, and its tectonic plates do not move. Venus has no natural satellites or rings, and its day lasts 243 Earth days, rotates westward that for this reason one of its hemispheres remains in total darkness for 58 days. Venus is believed to have no liquid core. Its volcanoes have now been inactive for 500 million years, and its tectonic plates are not moving. Venus has no natural satellites or rings, and its length is 243 Earth days, it rotates westward and for this reason one of its hemispheres remains in total darkness for 58 days.

Earth – the third planet from the sun

First of all, it is the only planet that knows that there is life in different species (millions of species) and, of course, we humans. It is the fifth largest planet by mass and the third largest planet from the sun. Earth was formed 4.5 billion years ago and has a natural satellite – the moon. Its name comes from an ancient Greek goddess named Gaia. It has a shape like Mars and Venus – it is a massive sphere. It orbits the Sun in 365 days and revolves around its axis. It is the third, counting from the Sun, and the fifth largest planet of the US.

Among the planets of the solar system, Earth is the only planet whose surface is dominated by a liquid element, i.e. Earth is covered by 71% water (97% seawater and 3% fresh water. The atmosphere consists of 78%) nitrogen, 21% oxygen and 1% argon (plus carbon dioxide and water vapor). Since the Earth’s atmosphere is mainly built up by two gases, nitrogen and oxygen, it makes life on Earth possible. The Earth is divided into 2 large areas with polar climates. The most extreme temperatures on the planet are 59 ° C in Libya and -89 ° C in Antarctica. The inclination of the Earth’s axis in relation to the Sun causes the seasons. 70.8% of its surface is covered by water, and 29.2% by continents and islands.

Mars – the fourth planet from the sun

Mars is the fourth in order of distance from the Sun, the second closest to Earth, and the seventh in size and mass H / S It is often called the „red planet” because of its red color, which is due to iron trioxide on its surface. Mars is an „Earth planet” with a thin atmosphere, whose surface combines the Moon’s collision craters and the Earth’s volcanoes, valleys, deserts and polar ice caps. Mars’ rotation around its axis is 24 hours and 37 minutes.

It is named after the Roman god of war, Mars. Its two satellites were named after the two sons of the mythological Mars, Deimos and Phobos. Mars formed 4.5 billion years ago from a planetary disk where other planets were formed. Today it is almost certain that Mars in its early stages of evolution was covered in some parts with liquid water at a depth of at least a few meters, although there are indications of at least one ocean. Thus, there is a possibility that Mars was a carrier of life in the form of germs(but it is certain that it did not evolve above), and the view that in that case life on Earth could have originated from Mars is confirmed. Mars lost its magnetosphere 4 billion years ago, so the solar wind interacts directly with the planet’s ionosphere, repelling humans from it. Mars’ atmosphere consists of 95.32% carbon dioxide , 2.7% nitrogen and 1.6% argon . It is very rare, and the pressure on the planet’s surface reaches an average of 0.60 kPa, which is less than one centimeter on the Earth’s surface (101.3 kPa). It is practically equal to the atmospheric pressure at an altitude of 35 km from the Earth’s surface. Therefore, an astronaut will certainly need a spacesuit to walk on its surface. Due to the sparse atmosphere, the speed of sound is low, and sounds do not propagate very far, only a few tens of meters. So Mars, in addition to being a desert, is also a quiet planet. Mars has two small satellites, Fear and Deimos. It is assumed that these satellites are asteroids that circled it due to the planet’s gravity, but it needs to be studied carefully to determine this. Phobos orbits Mars in 7 hours and 39 minutes, at an average distance of only 9,377 kilometers from the planet, closer to its home planet than any other satellite in the solar system.

Jupiter – the fifth planet from the sun

It is the largest planet in the system – in size and mass. It is the fifth planet in a row starting from the Sun. It is a gas giant, whose mass is slightly less than one millimeter of the solar system, but is two and a half times the mass of the other planets in the solar system. Jupiter, along with Saturn, Uranus and Poseidon, is called the gas giants. The planet was known to ancient astronomers and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Zeus. It may also have a rocky core composed of heavier elements.

Jupiter is believed to consist of a dense nucleus with a mixture of elements, a layer of liquid metallic hydrogen with a small solar envelope, and an outer layer of mostly molecular hydrogen. Beyond this basic structure, there is still great uncertainty. The core is often described as rocky, but every detail in its composition is unknown, as are the properties of the materials at temperatures and pressures at such depths. 1997 gravitational measurements show that Jupiter’s core has a mass of 12 to 45 times that of Earth, or about 3-15% of Jupiter’s total mass. The presence of a nucleus for at least part of Jupiter’s history is suggested by planet formation models for the initial composition of a rocky or icy nucleus, which is large enough to gather some of the volume from hydrogen and helium from the early solar nebula. Assuming it existed, it may have shrunk as streams of hot, liquid metallic hydrogen mixed with the molten core and transported its contents to higher levels inside the planet. The core may now be completely absent, as measurements are not yet accurate enough to rule out this possibility.

Saturn – the sixth planet from the sun

It is the sixth planet in terms of distance from the Sun and the second largest in the Solar System after Jupiter, with a diameter at the equator of 120,660 kilometers and belongs to the so-called Gas Giants. Saturn has nine rings, which consist of dust and ice particles, and 62 satellites, excluding small satellites and propellers. Saturn’s largest satellite, Titan, is the only satellite in the Solar System with a dense atmosphere. The rotation of the gases covering the planet does not take place uniformly. It takes 10 hours and 14 minutes to rotate areas on the equator, and 10 hours and 39 minutes to rotate other areas. Its atmosphere consists mainly of hydrogen at 96.3% and small amounts of helium 3.25%. Characteristic of this planet are Saturn’s Rings – there are 9 of them. They consist mainly of ice and in smaller amounts of rock debris orbiting Saturn. They form individual narrow bands or ribbons depending on the density of the material.

Minimal amounts of methane, methane, acetylene, ammonia and phosphine have also been identified. Saturn’s highest clouds consist of ammonia crystals, while lower clouds appear to consist of either ammonium sulfide or water. The atmosphere has a much lower solar content compared to the Sun. The amount of heavier elements in the sun is not exactly known, but it is believed to correspond to the amounts in the Solar System when it was in the process of formation. It is estimated that the total mass of these elements is 19-31 times that of the Earth, and they are concentrated mainly in Saturn’s core. The planet has strong winds, the speed of which reaches 1,800 km/hr. Saturn’s magnetic field is only slightly smaller than Earth’s.

Uranus – the seventh planet from the sun

Uranus is the seventh planet away from the Sun and one of the planets without a solid crust, the fifth in terms of mass in the Solar System, and its name comes from an ancient Greek deity. Uranus was the father of Saturn, which was the father of Zeus. Uranus cannot be seen from Earth like the other planets in the Solar System because it is apparently large and, combined with its slow motion, could not be recognized by the ancients as a planet. William Herschel announced the discovery of this planet in March 1781. Uranus is a large planet, one of the four gas giants of our solar system, but in terms of structure it looks more like Neptune, not the other two. Due to its great distance from Earth, it is barely visible to the naked eye. In 1977 it was discovered that Uranus has a ring system, and Voyager 2, during its approach to the planet in January 1986, studied the structure of these rings and discovered 10 more satellites, bringing the number of satellites to 15. The wind on Uranus blows at speeds of up to 900 km/hr. It takes Uranus 84 years to complete one orbit of the Sun.

All the rings and satellites are almost at the same level as the planet Ecuador. It has a rocky core the size of Earth, covered by a deep „ocean” of water and ammonia, surrounded by an atmosphere consisting of hydrogen and methane. The features that distinguish Uranus from other planets are that its axis of rotation is almost on the ecliptic, the level at which it orbits the Sun. So the sky looks like it’s rolling over black matter. Because its rings move around the equator, the whole system looks like a moving target. Uranus’ mass is 14.5 times that of Earth. Because of this mass, it is the fourth largest of the large planets in the solar system. Its diameter is slightly larger than that of Neptune with a total density of 1.27 g / cm, the second densest planet in the Solar System after Saturn.

Neptune – the eighth planet from the sun

It is the eighth and penultimate planet in distance from the Sun, as it is 4,500,000,000 km away from it. It is not visible to the naked eye, but it can be seen in binoculars. Most of the information and images of this planet came from NASA’s Voyager 2 spacecraft, which passed by it in August 1989. Neptune’s structure is quite similar to that of other gas planets. Therefore, Neptune, as well as Saturn and Jupiter, emit more energy (in the form of infrared or thermal radiation) than it receives from the Sun.

At its center is a core of solid rock and ice. This core is surrounded by a mantle of stony chemical ice, such as water, ammonia and methane. In the deeper areas of this mantle,It is believed that denser materials sink into the core and burn due to the high temperatures and pressures there, releasing energy. It can be said that it rains diamonds in Neptune, because the densest material that sinks and burns in Neptune is diamonds. As we ascend, we gradually go from a solid state to a gaseous state and into Neptune’s atmosphere due to a decrease in pressure and temperature. In the upper layers of the planet’s atmosphere there is a layer of hydrogen, helium and methane clouds, from which the planet’s color is derived. As with Uranus, Neptune’s methane absorbs the red spectrum of light radiation.

Why is Pluto no longer a planet in the solar system?

Pluto is no longer considered a planet in the solar system due to changes in the definition of a planet made by the International Astronomical Union (IAU) in 2006. Previously, Pluto was considered the ninth planet in our system, but the new definition has caused it to lose that status. Here’s why:

Definition of a Planet by the International Astronomical Union (IAU): According to the new definition, for a celestial body to be considered a planet, it must meet three main criteria:

1. Orbiting the Sun: The body must orbit the Sun.
2. Large Enough Mass: The body must have a large enough mass for its own gravity to form it into a near-spherical shape.
3. Clearing the Surrounding Orbit: A body must not share an orbit with other bodies of similar mass. In practice, this means that a body must „clear” its neighborhood of other objects without casting a shadow on other asteroids and small bodies.

Pluto met the first two criteria, but did not meet the third. There are many other objects such as asteroids and other celestial bodies in its orbit area. As a result, in 2006, the International Astronomical Union announced that Pluto was demoted from being a planet and was given a new category – „orbiting the Sun,” but no longer a planet. Pluto has been classified as a „transneptunian object orbiting the Sun,” with similar bodies in the area known as Plutonids.

This change was the result of a more precise definition and a desire to avoid a large number of objects being considered planets. Although Pluto has lost its status as a planet in the traditional sense, it remains an important research object in our solar system.

The Moon – a natural satellite and its role in the solar system

The Moon, as one of the distinctive celestial bodies in the night sky, is a natural satellite of the Earth. This body orbits our planet, located about 384,400 kilometers from it. Its unique properties and functions make it an important influence not only on the Earth, but also on life on it.

The Moon’s role in the Solar System: The Moon plays several key roles in the Solar System:

1. Stabilizing the Earth’s Rotation: One of the most important aspects of the Moon’s role is its effect on stabilizing the Earth’s rotation. Through gravitational interactions, it helps maintain a constant axis of rotation, which has implications for the even change of seasons and our climate.
2. Impact on Ocean Tides: The moon generates tidal forces that affect tides in oceans around the world. This phenomenon has a significant impact on marine ecosystems and human life related to the seas and oceans.
3. Night Lighting: Nighttime visibility is often provided by the moon. The sunlight reflected by its surface allows us to observe our surroundings in the dark and has an impact on our nighttime activity.

The conclusions are clear – the Moon is not only a beautiful object in the night sky, but also an important element affecting life and the environment on Earth. Its role in the Solar System is significant and shows how complex astronomical interactions affect our everyday world.

The planets of the solar system are also divided into certain types:

Gas planets – also known as gas giants. They are characterized by the fact that their surface is not solid, they also do not have a dense atmosphere and consist primarily of gas or ice. Such planets are Jupiter, Saturn, Uranus and Neptune.

Rocky planets – that is, one that has a rocky or rocky-ice half. Compared to other planets, rocky planets have a low mass, a solid surface and a high density. Such planets include Mercury, Venus, Earth and Mars.

The size of the planets of the solar system – a summary

Planets of the Solar System – Frequently Asked Questions