NIRISS: Near-infrared Imager and Slitless Spectrograph

NIRISS is packaged with the guide camera (fine guidance sensor [FGS]) and will be capable of imaging and wide-field grism spectroscopy as well as interferometry.

Closer to home, JWST’s infrared optics will make its pictures look slightly different from Hubble’s. Dusty regions in galaxies, as well as some types of nebulae, will be transformed because of the way that different types of light interact with dust. Where Hubble sees visible light that is scattered by the dust, JWST will see through the dust into the star-forming regions inside. Images produced by the infrared channel of Hubble’s Wide Field Camera 3 give a sneak preview of what JWST will see, but with only a fraction of the detail that the new telescope will offer.