Astro – Concept, types and characteristics

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

Galaxy - Universe - Astro
Not all existing stars are visible to the naked eye.

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 singular, unique elements, whose existence is supposed or has been verified by means of scientific methods of spatial observation; for this reason they constitute a category of astronomical objects, among which there may be multiple objects, such as planetary rings or asteroid belts, made up of many different elements.

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

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

Astros of the Solar System

Solar System - Planets
The length of the solar system exceeds 4.5 billion kilometers.

The Solar System, as we know, is the name given to the neighborhoods of our Sun, the star around which the planets and other elements that make up a kind of immediate spatial ecosystem orbit. Extends from the Sun itself at its center, to the outer edges where clouds of mysterious objects exist, 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 are a diverse number of stars, such as:

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


Sunlight - sun
The closest known star to our planet is the Sun.

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

Stars can be of different types, depending on their size, atomic content and the color of the light of their incandescence. The closest to our planet and known is the Sun, although at night a variable number of stars can be seen in the distance of the sky. There are an estimated 250,000 million stars in our galaxy.


Earth - Solar System - Planets
Earth is the only planet with liquid water in huge quantities.

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 more condensed, thus acquiring different physical and chemical properties. There are gaseous planets (like Jupiter), rocky planes (like Mercury), frozen planets (like Neptune), and there is Earth, the only planet with liquid water in enormous quantities, and therefore the only one with life, that we know of.

According to its size, one can also speak of dwarf planets: some that are too small to rub shoulders with ordinary planets, but at the same time too big to be considered asteroids, and who also lead an independent existence, that is, they are nobody’s satellites.


The Moon - Natural Satellite - Planet
The only satellite of our planet Earth is the Moon.

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

Such is the case of the only satellite of our planet: the Moon, and of 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 hooked on the gravitational force that keeps them in orbit.


Astro - comet
Comets could come from clusters of trans-Neptunian objects.

Comets are called the various mobile celestial bodies, composed of ice, dust and rocks of different origin. These bodies orbit the Sun in elliptical, parabolic, or hyperbolic orbits, and they are recognizable because, as they approach the star, the 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, like the famous Halley’s Comet, which passes us every 76 years.

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


Astro - asteroid
Some asteroids roam through space and can pass through each other in planetary orbits.

Asteroids are rocky objects of various composition (generally metallic or mineral elements) and irregular shape, much smaller than a planet or a satellite.

Devoid of atmosphere, most of those that make life in our solar system are forming a great belt between Mars and Jupiter, thus separating the inner planets from the outer ones. Others, on the other hand, roam through space and can cross each other in planetary orbits, or become satellites of some major star.


Meteorites - Astro
Meteoroids are fragments of comets and asteroids that have been left wandering.

This is the name given to the minor 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 can 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 the atmospheric air heats them up and totally or partially vaporizes them. And in some cases, fragments of the meteor can hit the Earth’s surface.


Astro - nebula
Nebulae can be the product of the destruction of a star.

Nebulae or nebulae are gas clusters, mainly hydrogen and helium, as well as cosmic dust and other elements, which are scattered in space, held more or less in place by gravitational forces. Sometimes the latter will be intense enough to begin to compact all this stellar material and, in this way, give rise to new stars.

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

Follow in: Nebulae


Astro - Galaxy
The galaxy in which our solar system is located is the Milky Way.

The star clusters, each one perhaps with its own solar system, together with nebulae, cosmic dust, comets, asteroid belts and other celestial objects, constitute larger units known as galaxies.

According to the number of stars that make up a galaxy, we can speak of dwarf galaxies (107 stars) or giant galaxies (1014 stars); but we can also classify them according to their apparent shape, into spiral galaxies, elliptical galaxies, lenticular galaxies and irregular galaxies.

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