Why do poison toads attend a frog orgy? Are you aware there is irrefutable evidence of intelligent life on Mars? And if the moon takes a month to revolve around Earth, why is it seen over Detroit every night?

Those strange questions - and a bizarre variety of theories - were contained in several dozen letters received by the nation's science writers and entered in a contest of "Ideas Galileo Never Thought Of."The Northern California Science Writers Association sponsored the contest last month during the annual meeting of the American Association for the Advancement of Science, held in San Francisco.

Science writer James Cornell, publications manager at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., swept first, second and third places with letters that landed on his desk.

The winning entry came from a Cambridge woman befuddled by news of mass mating rituals among frogs in Malaysia.

"What I have been wondering is whether all those different kinds of frogs managed to find their own kind of frog to mate with, what with the crowds and confusion and all; or whether they got all mixed up, which would mean that by now we are faced with the specter of ever new varieties of weirdo frogs," she wrote.

"Also, what were the poisonous toads doing there? They're not frogs, after all, and why should they even bother showing up at a frog orgy, just because they happen to be amphibious and hop?"

Detroit Free Press science writer Nancy Ross-Flanigan got an ungrammatical letter from a man who didn't know Earth rotates as the moon orbits it.

"The moon is supposed to travel around the Earth in a month time. Then what is this moon that revolve around the city of Detroit every day to every other day? And what is it doing?" he asked.

In another letter to Cornell, a Cincinnati man asserted his 12-year study of Mars photographs "resulted in irrefutable evidence of a civilized society of intelligent beings on the red planet."

Cornell said the writers of such letters "are harmless. They just have a skewed view of what the world is. I wouldn't want anyone to make fun of them. . . . They are simply attempting to establish their own version of scientific reality."

Charlie Petit, a San Francisco Chronicle science writer and president of the National Association of Science Writers, got a letter from a man who theorized continents formed and life on Earth started when a moon named "Yasoon" hit the planet.

Such correspondents mean to be serious, and while their ideas "may be silly and funny, I would never regard the people who think of them as ridiculous," Petit said. "I tip my hat to them for daring to say things that elicit giggles. I would not want to be a member of a society where nobody came up with crazy ideas."

Some offer more than ideas.

"I am willing to . . . have one of my hands amputated and scientifically demonstrate how Regenerative Medicine Works. As a result, a new hand will grow back," said a Brazilian man's letter to a scientist at the University of California, Irvine.

The scientist forwarded the letter to free-lancer Lynne Timpani Friedmann, then a university spokeswoman, with a note saying, "Please add this to the whacko file."

The contest's second-place letter, written by a Texas man, began: "Dear Sir: It is generally believed by scientists that the Earth is a giant magnet, but this is not quite true . . . The Earth is, in reality, a GIANT Photoelectric Cell."

In third place, from South Carolina, was this complete letter: "Dear Presidents, Directors and Other Communications Coordinators, Global abstinence from March 15 through April 15, combined with curative measures, as needed, can virtually eradicate gonorrhea, and much more. How many months have 11 days?"

Among other contest entries:

-A letter to Petit outlined a new theory on "The Nature and Treatment of Stupidity - Diagnosis and Prognosis." It began: "Human beings (deceitful neurotic talking predators) are uniquely stupid organisms because they are talking organisms."

-A Connecticut man's letter to Scientific American magazine contended the universe didn't start with the "big bang," but with a "big knock."

-A Miami Beach man's letter to Cornell claimed credit for being the genius who "suggested that spare tires be narrow so they would occupy less trunk space," "suggested a method for curing mental disease with electronics" and "presented some evidence that black holes do not exist."

-One man's letter detailed a "formula for THE NATURE AND NATURAL ORDER OF THE UNIVERSE." His simple theory: "What must be, must be, and what cannot be, cannot be. Such is Mother Nature's way of informing mankind of right and wrong."