How many planets are there in the Solar System, universe and Milky Way
The universe is a vast space in which there are countless planets, stars, satellites and celestial bodies. Everything that we know or can come to know is within the universe. However, given its incredible and infinite immensity, humans have been grouping everything that we discover into categories. Thus, the universe is divided into groups of galaxies and galaxies, these galaxies are divided into systems and, finally, within these systems we find different planets, stars and celestial bodies.
How many planets are there in the solar system
The Solar System is the planetary system in which we live. We speak of a system because it brings together a large number of planets and astronomical objects that orbit, either directly or indirectly, around the Sun, a star that constitutes more than 99% of the mass of the entire system. 
How many planets are there in the solar system ? Before answering this question, it is necessary to clarify what is considered a planet. A planet is a celestial body that orbits around the Sun, that by its mass has a rounded shape and that its orbit does not interfere with others. That is why since 2006 Pluto is no longer considered a planet, since although it fulfills the first two, its orbit intersects that of Neptune.
Thus, these are the 8 planets of the solar system ordered according to their proximity to the Sun:
- Mercury : it is the closest planet to the Sun and, in addition, it is the smallest in the entire solar system. Its size is similar to that of our Moon, being a little larger than this. A curiosity about mercury is that, being so close to the Sun, it has a totally burned face while the other, the one that is not in contact with the sun’s rays, is frozen.
- Venus : due to its size, density and volume, it is the planet in the solar system that is most similar to Earth. One of its main characteristics is that it rotates in reverse from the rest of the planets.
- Earth : it is our planet and, so far, the only one known to have supported life. It is known as the blue planet because of the large amount of water found on its surface.
- Mars : known as the red planet, it has some characteristics similar to Earth that allow us to think that it may have harbored some type of life, for example, the presence of frozen water.
- Jupiter : it is the largest planet in the Solar System, in fact it is a thousand times larger than Earth. However, it is mostly made up of gases, especially hydrogen and helium.
- Saturn : its main characteristic is the more than 10,000 rings of rock and ice around it. Like Jupiter, Saturn is also basically made up of gases.
- Uranus : it is the third planet in the Solar System in terms of size, in addition, it has a characteristic that makes it different from all others, and that is that it orbits sideways.
- Neptune : it is the planet furthest from the sun and, as a consequence, it is the one with the lowest temperature.
We have already explained that Pluto is no longer considered a planet, however, it is possible that in the coming years the list of planets in the solar system will increase to 9 . The ninth planet may be known as “Planet Nine”. If it has not yet been added to the list, it is because it has not been observed, since it is very far from our position. It would be the planet farthest from the sun and its existence has been intuited thanks to the mathematical calculations of an astronomical team. Thus, we must be attentive to new discoveries in this area in case we should add one more planet to this list of planets in the solar system.
The Milky Way is the galaxy in which the Sola r System is located and, as a consequence, the galaxy in which the Earth and ourselves are located. Our galaxy is within a galaxy system known as the Local Group and, together with another galaxy called Andromeda, is the largest in this group.
The diameter of the Milky Way is 100,000 light years, that is, it is immensely large. That is why if we want to know how many planets there are in the Milky Way it is impossible to count them one by one. On the one hand, because there are so many, but on the other hand because we don’t have enough technology to be able to detect them all. However, many astronomers have carried out different studies and calculations that allow us to approximate the number of planets in the Milky Way.
The latest study carried out in this regard  , which is also the most exhaustive in history, affirms that there are about 160,000 million planets in the Milky Way . This study was done by observing 100 million stars with telescopes and gravitational lenses, in addition, the results obtained were combined with those of other previous studies, being the most complete ever carried out at the moment.
In addition to answering the question of how many planets there are in the Milky Way (160,000 million), interesting data also emerged such as that, on average, for each star there are 1.6 planets or that 62% of them are, at least, 5 times larger than the earth.
Now comes the million dollar question: How many planets in the universe ? And the reality is that it is not possible to give an answer or that it is approximate. Taking into account that we do not even know the extent of the universe and that the portion of the universe that we have observed (the observable universe) may not be even 0.1% of the universe, the reality is that it is impossible to speak of figures about the real number of planets in the universe.
However, simply to understand the magnitude of the figures we are talking about, we can make a simple rule of three extrapolating the data we know about the universe, however, we repeat that it is not a true number, since we do not know too many parameters.
If we take into account that our solar system has 8 planets and we extrapolate that number of planets in all solar systems, we can multiply to obtain the number of planets in the universe :
- In our solar system there are 8 planets.
- In our galaxy there are 300,000 million solar systems.
- There are more than 2 billion galaxies in the observable universe.
If we multiply 8 (planets) by 300,000,000,000,000 (of solar systems) by 2,000,000,000 (of galaxies) it gives us that, only in the observable universe there can be about 4,800,000,000,000,000,000,000,000,000 planets .