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Earth was formed around 4.5 billion years ago and our solar system is one of more than 100 billion stars in our galaxy, and it is estimated there are over 100 billion galaxies in the universe (some maintain there are about 2 trillion galaxies in the universe). Going to the opposite and most downsizing direction, however, the universe is made of atoms, and the atom is composed of a nucleus and one or more electrons around the nucleus.
It is estimated there are about 100 trillion (1014) cells in our body and human body is composed of about 1028 atoms. What is interesting is that most of the space in the atom is unoccupied. If the size of atom was the size of the earth, the nucleus and an electron would be the size of a football stadium and a football, respectively, and the rest in between would be just empty. If we took out all the empty space between nucleus and electrons in the body in the same way, the size of our body would be just as small as a grain of table salt.
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