Cosmos - Carl Sagan [56]
*On Mars, where erosion is much more efficient, although there are many craters there are virtually no ray craters, as we would expect.
*As far as I know, the first essentially nonmystical attempt to explain a historical event by cometary intervention was Edmund Halley’s proposal that the Noachic flood was “the casual Choc [shock] of a Comet.”
†The Adda cylinder seal, dating from the middle of the third millennium B.C., prominently displays Inanna, the goddess of Venus, the morning star, and precursor of the Babylonian Ishtar.
*It is, incidentally, some 30 million times more massive than the most massive comet known.
*Light is a wave motion; its frequency is the number of wave crests, say, entering a detection instrument, such as a retina, in a given unit of time, such as a second. The higher the frequency, the more energetic the radiation.
*Pioneer Venus was a successful U.S. mission in 1978–79, combining an orbiter and four atmospheric entry probes, two of which briefly survived the inclemencies of the Venus surface. There are many unexpected developments in mustering spacecraft to explore the planets. This is one of them: Among the instruments aboard one of the Pioneer Venus entry probes was a net flux radiometer, designed to measure simultaneously the amount of infrared energy flowing upwards and downwards at each position in the Venus atmosphere. The instrument required a sturdy window that was also transparent to infrared radiation. A 13.5-karat diamond was imported and milled into the desired window. However, the contractor was required to pay a $12,000 import duty. Eventually, the U.S. Customs service decided that after the diamond was launched to Venus it was unavailable for trade on Earth and refunded the money to the manufacturer.
*In this stifling landscape, there is not likely to be anything alive, even creatures very different from us. Organic and other conceivable biological molecules would simply fall to pieces. But, as an indulgence, let us imagine that intelligent life once evolved on such a planet. Would it then invent science? The development of science on Earth was spurred fundamentally by observations of the regularities of the stars and planets. But Venus is completely cloud-covered. The night is pleasingly long—about 59 Earth days long—but nothing of the astronomical universe would be visible if you looked up into the night sky of Venus. Even the Sun would be invisible in the daytime; its light would be scattered and diffused over the whole sky—just as scuba divers see only a uniform enveloping radiance beneath the sea. If a radio telescope were built on Venus, it could detect the Sun, the Earth and other distant objects. If astrophysics developed, the existence of stars could eventually be deduced from the principles of physics, but they would be theoretical constructs only. I sometimes wonder what their reaction would be if intelligent beings on Venus one day learned to fly, to sail in the dense air, to penetrate the mysterious cloud veil 45 kilometers above them and eventually to emerge out the top of the clouds, to look up and for the first time witness that glorious universe of Sun and planets and stars.
†At the present time there is still a little uncertainty about the abundance of water vapor on Venus. The gas Chromatograph on the Pioneer Venus entry probes gave an abundance of water in the lower atmosphere of a few tenths of a percent. On the other hand, infrared measurements by the Soviet