means: like spiders, they lengthen and retract, and are propelled by their own forces - because the magnetic forces of the Earth and the Moon attracting the suspended body and it together, the effect is as if there were no attraction - so that at the end its mass will turn of its own accord to the Moon."
I know, you've never read it. That's because it was published just a little before your time. Say, 1634. The author: Johannes Kepler.
Surely you've heard of Johannes Kepler. He was the fellow who, appropriately enough, discovered Kepler's three laws of planetary motion, in which -- everyone sing along, now:
(1) the planets move in elliptical orbits with the Sun at one focus;
(2) the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central body and that arc;
(3) there is an exact relationship between the squares of the planets' periodic times and the cubes of the radii of their orbits.
Not just the law, but a good idea. Break the laws of planetary motion, and you get a fine, or, alternately, your planet sinks into the hot gaseous bowels of the sun, while you run about, yelling and screaming. Your choice. Hint: Take the fine.
Somnium is a little quaint to read today, but then again, what written in the early 17th Century isn't? Even Shakespeare comes across as a little twee now and again. But for its time, man, it had everything : Wild, fantastic ideas, a breathtakingly original premise, and, of course, that most important part of any novel's publicity cycle: Controversy. This book was so hot that it couldn't be published in Kepler's lifetime. They waited until Kepler was planted four years before they slipped it onto the shelves.
The controversy regarded the mode of propulsion in the story: Magic, provided by his mother, Katharina Kepler. Nowadays, magic is simply a cheap trick employed by lazy writers who don't want to bother with giving the implausible events in their books a reasonable explaination (we generally call these people "fantasy writers," though they are not the only ones -- every time someone in the "Star Trek" universe discovers a new type of sub-atomic particle to get them out of a scrape at the last moment, it's magic!). But back in the 17th century, if you were thought to know anything about magic, you didn't play birthday parties and bar mitzvahs. You were strung up and tortured until you admitted that, why, yes, you and Satan regularly got together to eat children and do the shag nasty. Was there some sort of problem with that?
Which is in fact what happened to Katharina Kepler: Round about 1619, several years after Somnium was initially completed, Katharina was accused and tried for being a witch. Kepler had to travel to Württemberg to defend his mother -- and the reason she was eventually released had less to do with her innocence (and of course she was innocent; like nearly all women charged with witchcraft, Katharina Kepler was at most a screwy old biddy with some practical knowledge of folk remedies) than with the fact that the authorities didn't follow the correct torture procedures ("You idiot! You were supposed to impale her there , not there! Yeeesh!"). Kepler's use of his mother as a convenient mode of space propulsion was not so very convenient for mom.
Moving away from the mommy-whipping consequences of the book and turning to the actual contents, Somnium has some breathtaking leaps of intellect and imagination. When Kepler started work on Somnium , the heliocentric theory (the one that states that planets move around the sun instead of the earth) was still a zany and highly debatable idea, and the minutiae of gravity awaited Newton's Philosophiae Naturalis Principia Mathematica in 1687.
Into this scienti fi c void, Kepler lept, and sketched out some tantalizing concepts: Zero gravity, space travel, extraterrestrial life ( Somnium postulates a race of creatures living on the moon), the environs of space being