Graphic showing a simulated WFIRST (Roman Space Telescope) image of a portion of the Andromeda galaxy overlaid on a ground-based image of Andromeda. A photograph of the full Moon is shown in the upper right corner for scale. The Moon takes up about one-thirtieth of the full image. Andromeda is the largest object, filling about one-third of the image, or ten times the area covered by the full Moon.

Andromeda has an oval shape and is oriented at an angle of about 45 degrees clockwise from horizontal on the sky. Its central region, which is near the center of the image, is fuzzy white, with darker arms spiraling around it. The main part of the galaxy is surrounded by a hazy bluish glow.

Just to the right of Andromeda, directly between its center and the Moon, is a much smaller, fuzzy white oval-shaped galaxy with a bright white core and no spiral structure. The Moon looks ten times larger than this galaxy; Andromeda looks 100 times larger.

Overlaid on the upper left portion of Andromeda is a three-by-six array of squares. This represents WFIRST's field of view, the footprint of the 18 detectors that make up its Wide Field Instrument (or camera). The squares are not touching each other and they do not form a perfect rectangle. Instead, the squares are slightly offset from each other, forming a sort of space invader shape turned on its side. Within the squares is simulated WFIRST imagery of Andromeda. The WFIRST imagery is noticeably clearer and more detailed than the ground-based imagery. The entire array of squares, including the space between the squares, covers about one-fifth of the galaxy, or nearly twice the area of the full Moon.