Word: ultraviolet
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...stream of gas followed the ash and spread into the vacuum above the moon's surface. The gas contained carbon molecules of various sorts, and ultraviolet light from the sun made them glow brilliantly, accounting for the bright streak on the spectrogram...
...said Dr. Calvin, that life first appeared something like 2 billion years ago when the earth's atmosphere was dominated by hydrogen compounds such as methane, ammonia and water vapor. Such simple organic compounds as acetic acid and glycine (an amino acid) are formed in the laboratory when ultraviolet light or electric sparks pass through such mixtures. Presumably, solar ultraviolet and natural lightning would do the same in nature...
This was enough to send Dr. Heil back to Manhattan for another close-up inspection. With mounting excitement he dated the marble, through ultraviolet examination, as from the 16th century. The workmanship, he found, was Renaissance in character. A few details-unsmoothed caliper marks on the cheeks, one wing of the Medusa head on Cosimo's armor -seemed unfinished. Otherwise the statue was in near-perfect condition...
...could be gathered on the ground. Eventually, the scientists agreed on the right to use both methods. Debris is no help in measuring fallout caused by explosions in space. ¶ Electromagnetic radiation. Control posts, equipped with photocells and low-frequency radio receivers could pick up the X rays and ultraviolet rays that turn into light and radio waves after an explosion. They could even pick up the light pulses resulting from a blast in space. ¶ The seismic method, which with astonishing accuracy has already detected the size and location of underground explosions thousands of miles away. Main drawback: seismographs...
...precisely. The nuclear fireball expands very fast at first, but both its temperature and pressure fall as it gets bigger. When its pressure equals that of the air, the ball stops expanding (for a megaton explosion, at a diameter of about one mile). The air also absorbs gamma and ultraviolet rays, confines radioactive particles to a comparatively small cloud...