Scientists are trying to work out the number of galaxies in the whole of our universe, and so far they have surveyed about 3% of our sky. They have found around 3 million galaxies in that section of the sky, so if the number of galaxies is the same around the whole of the sky, there is around a hundred million galaxies in the universe.
There are around a hundred million stars in a galaxy.
So, this means that there are around a hundred million galaxies, in each of which are a hundred million stars. This means there are 10,000,000,000,000 (or ten quadrillion) stars in the universe. Each star has “on average … at least 1.6 planets.”
That’s 16,000,000,000,000 (16 quadrillion) planets out there. And people say we’re the only ones to exist.
There’s actually something called the Drake Equation which estimates the number of extraterrestrial civilisations in just our Milky Way galaxy, and you can find more information about that here.