What are the stars?

We explain what the stars are and what the stars of the Solar System are. In addition, the types of stars that exist and their characteristics.

1. What are the stars?

It is known as stars, or more formally as celestial bodies, the various physical entities existing in the universe, from an astronomical perspective . In strict terms, the stars are unique, unique elements whose existence is supposed or proven by scientific methods of spatial observation ; for that reason they constitute a category of astronomical objects, among which there may be multiple objects, such as planetary rings or asteroid belts, composed of many different elements.

The elements that exist in outer space on our planet have fascinated humanity since ancient times , and much effort has been devoted to their observation and understanding, through telescopes, space probes and even a manned trip to the moon. Thanks to these efforts, we have been able to learn a lot about the other worlds that exist, the galaxy that houses them and the infinite universe that contains everything.

However, not all existing stars are visible to the naked eye , even with the help of an ordinary telescope. Others even require special scientific devices or their presence can only be deduced by the physical effects to which they subject other bodies around them.

2. Astros of the Solar System

The Solar System , as we know, is the name of the neighbourhoods of our Sun, the star around which the planets and other elements that make up a kind of immediate space ecosystem orbit. It extends from the Sun itself in its center, to the outer edges where there are clouds of mysterious objects , known as the Oort Cloud and the Kuiper Belt. The length of the Solar System to its last planet (Neptune) exceeds 4,500 million kilometers, equivalent to 30,10 Astronomical Units (AU).

In the solar system there is a diverse number of stars, such as:

• 1 star: the sun.
• 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
• 5 dwarf planets: Pluto, Ceres, Eris, Makemake and Haumea.
• 400 natural satellites
• 3153 kites

3. Stars

The stars are incandescent balls of gas and plasma , which due to their force of gravity remain in perpetual state of explosion by atomic fusion. This explosion generates huge amounts of light, electromagnetic radiation and even matter , as the hydrogen and helium atoms inside become heavier elements, such as those that make up our planet.

The stars can be of different types, depending on their size, atomic content and the color of the light of their glow. The closest to our planet and known is the Sun , although at night you can see a variable number of stars in the distance of the sky. It is estimated that there are about 250,000 million stars in our galaxy.

4. Planets

The planets are bodies of variable size and rounded shape , formed from the same gaseous matter that gave rise to the stars or that came from them, but infinitely colder and condensed, thus acquiring different physical and chemical properties. There are gaseous planets (like Jupiter), rocky plans (like Mercury), frozen planets (like Neptune), and there is Earth, the only planet with liquid water in huge quantities, and therefore the only one alive , that we know.

According to their size, we can also talk about dwarf planets : some that are too small to rub shoulders with ordinary planets, but at the same time too large to be considered asteroids, and also have an independent existence, that is, they are not satellites from no one.

5. Satellites

Orbiting around the planets, it is possible to find similar but much smaller stars, which attracted by their gravity remain in orbits more or less close , without falling into them or moving away from them at all.

Such is the case of the only satellite on our planet: the Moon, and the numerous stars of other major planets, such as the moons of Jupiter , estimated today at about 79. These satellites could have the same origin as their associated planet, or they could come from other origins, only to get caught in the gravitational force that keeps them in orbit.

6. Kites

The various moving celestial bodies, composed of ice, dust and rocks of different origin, are called comets . These bodies orbit the Sun in elliptical, parabolic or hyperbolic orbits, and are recognizable because, when approaching the star, heat melts its ice sheets and gives it a very distinctive gaseous “tail”. Known comets are part of the solar system and have predictable trajectories, such as the famous Halley comet , which passes by our side every 76 years.

The exact origin of comets is unknown, but everything suggests that they could come from groups of trans-Neptunian objects , such as the Oort Cloud or the Kuiper Belt, located about 100,000 AU from the Sun, in the limits of the Solar System.

7. Asteroids

Asteroids are rocky objects of different composition (usually metallic or mineral elements) and irregularly shaped, much smaller than a planet or a satellite. Lacking atmosphere , most of those who make life in our solar system are forming a large belt between Mars and Jupiter , thus separating the inner planets from the outer ones. Others, on the other hand, roam the space and can cross in the planetary orbits, or become satellites of some major star.

8. Meteoroids

This is the name of the smaller bodies of our solar system, less than 50 meters in diameter , but greater than 100 micrometers (and therefore larger than cosmic dust). They can be fragments of comets and asteroids that have been wandering, and that may very well be attracted by the gravity of the planets, entering their atmosphere and becoming meteorites. When the latter occurs, the heat of friction against atmospheric air heats and vaporizes all or part of it. And in some cases, meteor fragments can impact the earth’s surface.

9. Nebulae

Nebulae or nebulae are clusters of gas, mainly hydrogen and helium , as well as cosmic dust and other elements, which are dispersed in space, more or less retained in place by gravitational forces. Sometimes, the latter will be intense enough to start compacting all this stellar material and, thus, give rise to new stars.

In turn, these gas clusters can be the product of the destruction of a star , such as a supernova, or the agglomeration of material left over from the process of producing young stars. The nebula closest to Earth is the Helix Nebula (Helix), located 650 light-years from the Sun.

10. Galaxies

Star clusters, each perhaps with its own solar system , together with nebulas, cosmic dust, comets, asteroid belts and other celestial objects, larger units known as galaxies. According to the number of stars that integrate a galaxy, we can talk about dwarf galaxies (107 stars) or giant galaxies (1014 stars); but we can also classify them according to their apparent form, in spiral galaxies, elliptical galaxies, lenticular galaxies and irregular galaxies.

The galaxy in which our solar system is located is the Milky Way, named in honor of the mother’s milk of Goddess Hera of the pantheon of the Ancient Greek civilization.