Amaze your friends with some mind boggling facts

There are roughly 10^22 litres of air in the atmosphere. Remember, that 10²² litres is 10000000000000000000000 cartons like the one below.

By a mind boggling coincidence, this is also just about the number of stars that are estimated to be in the universe and also the number of molecules in a litre of air.

Of course this is approximate because it depends on if you squash the gas in a litre of air and it isn't exactly certain where the atmosphere ends. There are a lot more air molecules squashed into a smaller space near the surface of the Earth than at the top of Mount Everest because of the pressure difference. And of course we can only estimate the number of stars in the universe because counting them at the rate of 1 a second would take 3*10^14 years which is a lot longer than the universe has been in existence!

Things that look like dots in the photograph on the left are galaxies, each containing billions of stars. It's fair to say that the world in which we live is in scale half way between the world of atoms and the world of galaxies and the universe as a whole.
Our own Galaxy, the Milky Way has between 200 and 400 billion stars. If you are having difficulty imagining these numbers don't worry, they are not easy for anyone. This is why we put numbers on them like 4 x 10^11. (4 x 10¹¹) It's just a short way of writing 400 billion because no-one can really imagine 400 billion.