To estimate how many planets there are in the universe, we will need three numbers. First, we need to estimate how many planets are for one star. Secondly, we need to estimate how many stars there are in the galaxy. Thirdly, we need to estimate how many galaxies there are in all space. Professor Ethan Siegel and assistant professor David Kipping took up this challenge and tried to determine the number of all planets in space.⁠ Obviously, it's hard to give a precise number, so we should stick to an absolute pessimistic scenario in each of the three variables.⁠ ⁠ _____⁠ ⁠ Studies from 2016 have shown that there are at least 2 trillion galaxies in the observable universe. According to scientists, the number of stars in the Milky Way ranges from 100 to 400 billion. Other galaxies have much, much more, and others have less. David Kipping assumes a pessimistic scenario, according to which one planet would correspond to one star. Let's assume that there is, in fact, only one planet per star. ...