Spectroscopy is a tool that astronomers use to better understand the physics of objects in space.

The spectrographs on board the James Webb Space Telescope (Webb) provide scientists with the data needed to analyse the materials that make up stars, nebulae, galaxies and the atmospheres of planets.

Light that enters the telescope is split into its different wavelengths by a grating or a prism, forming a spectrum. This spectrum is then focused onto a detector. Light from each chemical element has a unique spectrum, like a fingerprint. The spectrum’s pattern is analysed by astronomers to decipher which atoms and molecules are present in the source of light, and understand the physical and chemical characteristics of the source.

Instruments like NIRSpec and MIRI make spectroscopic observations of extended and complex targets (such as galaxies, nebulae, or crowded fields of stars or galaxies) in one single shot.

Webb is an international partnership between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).