Glossary term: Molecule

Description: A molecule is a group of two or more atoms which are bound together by what are known as chemical bonds and carries zero net electric charge. In chemistry, molecules are limited to atoms bound together by covalent bonds, but in astronomy ionic compounds are sometimes referred to as "molecules".

Molecules are present in conditions that range from the atmospheres of solar type and cooler stars and brown dwarfs; to the atmospheres, oceans, and icy regions of planets and moons; to icy material on comets and asteroids; as well as the colder parts of the interstellar medium. In order to form new stars it takes interstellar molecular clouds made mostly of hydrogen molecules (H2). A new star is formed as part of such a cloud contracts under its own gravity.

Molecules can be detected in space because under the right circumstances, as they rotate or vibrate, they absorb and emit electromagnetic radiation in narrow wavelength regions, typically in the radio or infrared. These "molecular lines" form patterns that allow for the identification of a molecule.

Related Terms:

See this term in other languages

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".