The Earth belongs to the solar system. The star of this system is the Sun, and the latter is orbited by 8 planets (Mercury, Venus, The Earth, Mars, Jupiter, Saturn, Uranus and Neptune). The universe is formed by an incredible number of galaxies, containing each of them billions of stars. But, how many planets are there in the universe?
We call exoplanets all the planets that are found outside the solar system. Through the last decades, the detection techniques of exoplanets have got better, to the point to send some telescopes into space in order to detect planets around other stars.
The Kepler telescope, operated from 2009 until 2018, observed an area of space containing 150,000 stars, searching for new planets. In total, the telescope detected more than 2,700 exoplanets and 2,000 more suspected planets.
Thanks to these results, astronomers have been able to get a rough number of planets per star, which nowadays is approximately 1 planet per star.
Of course, there are stars that don’t have any planets around them, and others that have lots of planets in orbit, such as the Sun.
The number of planets in the universe
The solar system belongs to a galaxy named Milky Way, which in turn belongs to a bigger group of galaxies called Local Group. These galactic structures get bigger and bigger until arriving at the superclusters, which can contain billions of galaxies.
In total, it is thought that in the universe exist approximately 2 trillion galaxies, each of them formed by tens of billions of stars, which in turn have a planet orbiting them. So, we can see that the number of planets in our universe is extraordinarily elevated.
In total, it is calculated that in the universe there are more than 20 sextillion planets (a 2 followed by 23 zeros).