The solar system
The Solar System is a region of space located in the Orion Arm of our Galaxy, the Milky Way , and includes a star, the Sun, and the bodies that orbit around it, together with their satellites.
Together with all the matter of which the Milky Way is composed, the Solar System orbits around the galactic center with a period of about 230 million years.
At the center of our galaxy is the black hole Sagittarius A*, pictures of which have recently been published.
Among them, the largest bodies are the planets, divided into rocky (the closest to the Sun, which lost most of their mass at the time of the Sun's birth) and gaseous (colder and more distant, which have retained the outer layer mass).
As the technique progressed, there has been an increase in the number of celestial objects observed. In order not to classify most of them indiscriminately as planets, it was necessary to define a new category of bodies: these are the dwarf planets , that is, those bodies orbiting around the Sun, of sufficient mass to have an almost spherical shape but which have not cleared the neighborhood around their own orbit.
To this category, in the Solar System, belong 5 bodies: Pluto, Eris, Makemake, Ceres and Haumea.
Asteroids are thousands of minor bodies, located in the main belt (between Mars and Jupiter), in the Lagrangian points L 4 and L 5 of the orbits of the planets (called Trojans ), and at the borders of the Solar System (in the Kuiper Belt , in the Diffuse Disc and in the Oort Cloud ).