Number 116 (Story #2), March 3, 1993 by Phillip F. Schewe and Ben Stein GEMINGA'S PROPER MOTION has been measured. Geminga is a pulsar that emits almost all its energy at gamma wavelengths. Its x-ray emission is weaker by a factor of 1000 and its optical emission---if the identification of an object called G'' as Geminga's optical counterpart is correct---is 2 million times less than the gamma; it seems to emit no radio at all. Italian astronomers at the Universities of Milan and Cassino have now reanalyzed optical images recorded over the period 1984-92 and have determined that Geminga moves across the sky at a rate of 0.17 arcsec/year and that its distance from Earth is about 300 light years (G.F. Bignami et al., Nature 25 Feb. 1993.) In the following article in the same issue of Nature, Neil Gehrels and Wan Chen of NASA/Goddard suggest that the supernova that created Geminga also created the "Local Bubble," the hot, low-density region of interstellar space containing our solar system. Taking into account Geminga's velocity and dating the presumed supernova (about 340,000 years ago) with Gamma Ray Observatory data on the slowing of Geminga's spin rate, Gehrels and Chen conclude that the supernova might have been in the right place to clear away the gas in our vicinity, leaving behind the bubble. (Science News, 2 Jan. 1993.)