In the Universe there can be between 100 and 100,000 planets for each star

In our galaxy alone there are about 400 billion stars and in the Universe there are about two trillion (2,000,000,000,000) galaxies. So to consider that for every star there are about ten planets is simply overwhelming. But it is also estimated that outside any solar system for each star there are between 100 and 100,000 wandering planets that roam through space. A small percentage of them were expelled from their own solar systems, but the vast majority have never known the heat of a star. Many are gas giants and still more are rocky and icy. Many of them contain the necessary ingredients for life. Maybe one day they will have their chance. Until then they will continue to travel through the galaxy and through the Universe, vastly outnumbering the vast number of points of light that illuminate the cosmos.

Astrophysicists calculate that on average in each solar system there are about ten planets, although they recognize that the average can be as low as three or as high as 30. "But ten seems a reasonable number based on what we know so far," says the astrophysicist Ethan Siegel. "According to simulations for every solar system like ours that forms in the universe there should be at least one gas giant (a jupiter) and between 5 and 10 smaller rocky planets that are expelled and are turned into wandering planets [ or interstellar planets] that do not orbit any stars ”.

With that data already, if it were minimally correct, it can be assumed that the number of wandering planets that have been expelled from its solar system is "comparable" to the number of planets that orbit a star.

So on the one hand there are the planets that orbit stars and on the other hand there are those that do not orbit stars because "they were separated from their parent star by the gravitational pull of their brothers."

And apart from those two types there are still yet another type of possible planets: the failed stars. Failed stars did not form around a star, but are objects that were on the way to becoming stars and did not succeed: they did not reach enough mass to start the nuclear fusion reaction. If they had succeeded, those bodies would have “turned on” and turned into a star. But since it was not like that, they stayed on objects "large and massive enough to stand up to the definition of a planet."

The problem with wandering planets of whatever type is that they are difficult to detect. They wander in the dark and are barely seen, but astrophysicists estimate that "for every star that forms, between 100 and 100,000 wandering planets also form, planets doomed to roam interstellar space."

credit: Astronomers alone in space find a new kind of planet.

Photo: Illustration representing a Jupiter-like planet wandering through space, without a parent star. Astronomers believe that wandering planets outnumber stars. Image: NASA / JPL-Caltech.

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