Number 187 (Story #2), July 11, 1994 by Phillip F. Schewe and Ben Stein THE INTERGALACTIC MEDIUM (IGM) MAY HAVE BEEN DETECTED , at least that part of it consisting of singly ionized helium. Using the Hubble Space Telescope (HST), a Dutch- British-French-US team of astronomers have sampled the light coming from the quasar Q0302- 003 (redshift of 3.286). They notice that ultraviolet light at a wavelength of 304 angstroms is being absorbed along the way, supposedly by the singly ionized helium making up part of the IGM. (Another presumed IGM component, singly ionized hydrogen, cannot be observed since, consisting of bare protons, it exhibits no atomic transitions.) Using the quasar approach to inferring the presence of the IGM is difficult because the quasar must be far away, so that the ultraviolet radiation can be redshifted into a range that can be detected by HST, and because it is rare for such a quasar not to lie behind several foreground neutral-hydrogen clouds, which could also absorb the ultraviolet. (P. Jakobsen et al., Nature, 7 July 1994.)