Malin 1 is the best example among giant low surface brightness galaxies. New observations of this object in 6 broad-bands allow us for the first time to perform a pan-chromatic study of the stellar population in its 200 kpc wide disk. We observe a spiral structure revealing a star forming disk. The colors indicate a long history with a low efficiency of star formation. It is well reproduced by a model of disk galaxy making it similar to the disk of the Milky Way or other nearby spirals, except for its extremely large angular momentum.

Our R-band data show that the optical light from Malin 1 corresponds well with the >2-arcmin extent of the galaxy's Hı content and continues well beyond previously published V-band optical light radial profiles. Analysis of our image yields improved understanding of the galaxy's properties. We measure ellipticity of 0.20 ± 0.03, implying inclination of 38 ± 3°, and we trace the radial profile to 77arcsec. A single dusty spiral arm is also weakly discernable, and is consistent with the rotation direction of the Hı and spiral structure of the inner disk. Possible scenarios for the origin of the spiral structure are discussed.