The fundamental particle of all matter is the atom, which is the basic building block of the universe. Atoms are made of protons, electrons, and for some elements, neutrons. Atoms give off light when electrons absorb and then release energy. The color emitted can reveal a lot about the makeup of atom, and therefore, the matter being observed. It is through this process that astronomers can study the composition of celestial objects far from Earth without having a sample of the actual object. In this topic, you will explore some basic information about atoms to learn how astronomers use them in their study of space.
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