From the enormous universe in which we exist to tiny atoms that make up the building blocks of everything around us, size matters when it comes to understanding the cosmos. Starting with our solar system, National Geographic explores the true meaning of the words "big" and "small". Our neighborhood of planets may seem vast but compared to the size of our Milky Way galaxy, our solar system is really tiny. And our galaxy is only one of about 100 billion galaxies in the cosmos. But every giant object in our expansive universe is made of tiny bits of matter – the atom – which is a universe within itself on a minute scale. Peer into the atomic world where scientists are using nanotechnology to develop lifesaving cures and ingenious inventions.