Astronomers think there could be as many brown dwarfs as stars like our Sun, but brown dwarfs are often too cool to find using visible light.  Using infrared light, the WISE mission could find many brown dwarfs within 25 light years of the Sun.  These two pictures show simulated data before and after the WISE mission (stars are not real). The simulated picture on the left shows known stars (white and yellow) and brown dwarfs (red) in our solar neighborhood. The picture on the right shows additional brown dwarfs WISE is expected to find. Image credit: NASA/JPL-Caltech