Description: A proton is a subatomic particle with positive electric charge. Protons are one of the main constituents of atomic nuclei, alongside neutrons. The number of protons is the "atomic number" of a nucleus, and each atom with a specific atomic number corresponds to a specific chemical element. The atomic nucleus of hydrogen is a single proton, and the most elementary nuclear fusion reaction in a star is when two protons collide, one of them decays, and a deuteron is formed, consisting of one proton and one neutron. Protons can also be found in the high-energy cosmic rays reaching us from outer space.

Related Terms:

• Atom
• Cosmic Ray
• Hydrogen
• Nuclear Fusion
• Nucleus
• Cosmic Ray Astronomy
• Electron

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".