By measuring the velocity and makeup of the plasma between stars and galaxies, XRISM will resolve more precisely than ever how these celestial objects are formed.

Spectroscopy is the measuring of the strength of light at different wavelengths, in the same way our eyes can see different shades of colors. In X-ray astronomy, by making a precise measurement of wavelength (energy) of X-ray photons in the universe, we can measure the temperature of celestial objects, the type of matter they contain, and their speed. The micro-calorimeter, Resolve, has excellent spectroscopic capabilities. On the other hand, imaging takes a picture of an object. By examining the shape and brightness distribution, we can learn about the spatial extent of celestial objects. XRISM has an X-ray CCD camera, Xtend, which can image objects over a wide field of view.