Therefore, it requires 1094 such books to print all the zeros of a googolplex (that is, printing a googol zeros). If each book had a mass of 100 grams, all of them would have a total mass of 1093 kilograms. In comparison, Earth's mass is 5.972 x 1024 kilograms, the mass of the Milky Way Galaxy is estimated at 2.5 x 1042 kilograms, and the mass of matter in the observable universe is estimated at 1.5 x 1053 kg.[citation needed]