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There is on average one planet orbiting every star in the Universe \citep{2013ApJ...764..105S, 2012Natur.481..167C}. \citep{2013ApJ...764..105S,2012Natur.481..167C}.  If this sounds exciting, you might wanna read the \href{https://www.authorea.com/10997/}{previous post} in this series. Our Galaxy (the Milky Way) is an immense disk of gas and stars with a diameter of about 100~000 light years, hosting about 100 billion stars and, therefore, also about 100 billion planets. Take a deep breath. Now, it turns out the Milky Way is just one of 100 billion galaxies that populate our Universe, a colossal expanding stretch of spacetime with an age of 13.7 billion years.  The math is trivial: There are about 10~000~000~000~000~000~000~000 = $10^{22}$ planets out there.   This number is extremely large. Apparently larger than the\href{http://www.npr.org/blogs/krulwich/2012/09/17/161096233/which-is-greater-the-number-of-sand-grains-on-earth-or-stars-in-the-sky}{ number of grains of sand} found in every beach and every desert on Earth.