What wavelength range does JWST's MIRI instrument cover?

JWST’s MIRI instrument covers wavelengths of about 5 to 28 micrometers. That range places it in the mid-infrared, beyond the near-infrared coverage of Webb’s other three science instruments.

MIRI combines a camera with spectroscopic capabilities. Its imaging system uses filters to create pictures of dusty star-forming regions, distant galaxies, planetary systems, and objects in the Kuiper Belt. Its spectrograph spreads infrared light into component wavelengths, allowing astronomers to identify molecules, measure temperatures, and study the chemistry of dust and gas.

Long infrared wavelengths are especially useful because cooler objects radiate strongly there, and infrared light can pass through dust clouds that block visible light. MIRI also helps Webb study distant galaxies whose light has been stretched, or redshifted, into the mid-infrared by the expansion of the universe.

Technical descriptions sometimes give a slightly more precise range, such as 4.9 to 28.8 micrometers, depending on the observing mode. The rounded 5-to-28-micrometer range is the standard canonical answer used in mission summaries and trivia references.