Where do stars form in galaxies? One way to find this out it to look for glowing hydrogen [ http://antwrp.gsfc.nasa.gov/apod/ap990312.html ], a material common to hot star-forming regions [ http://antwrp.gsfc.nasa.gov/apod/ap970119.html ]. To find large areas of glowing hydrogen [ http://chemlab.pc.maricopa.edu/periodic/h.html ], the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap950810.html ]'s NICMOS [ http://nicmos.as.arizona.edu/ ] instrument surveyed [ http://xxx.lanl.gov/abs/astro-ph/9903307 ] about 100 nearby spiral galaxies [ http://www.seds.org/messier/spir.html ]. Six of these galaxies [ http://oposite.stsci.edu/pubinfo/pr/1999/10/content/prc9910.txt ] are shown above: NGC 5653, NGC 3593, NGC 891 [ http://antwrp.gsfc.nasa.gov/apod/ap981220.html ], NGC 6946, NGC 4826 [ http://antwrp.gsfc.nasa.gov/apod/ap980711.html ], and NGC 2903. Each galaxy is many millions of light-years distant. NICMOS was calibrated to isolate a very specific type of light emitted by hydrogen gas in the infrared [ http://www.ipac.caltech.edu/Outreach/Edu/discovery.html ]. This emission is colored red in the above photograph [ http://oposite.stsci.edu/pubinfo/pr/1999/10/ ], and is relatively free from absorption by dark dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ]. These photographs show that stars are forming more vigorously in some parts of galaxies than others.