Dominating your twin (planet)

Ray Villard, a commentator on the website “Discovery News,” just put up a new post about the Pluto debate: Is it a planet? Or just some odd object captured by our solar system, or a moon of Neptune’s that went astray, or something else?

Then he suggests that Pluto is actually a double-planet system (or un-planet system) because its moon Charon has 12% of Pluto’s mass. This is so much that the center of gravity between the two “bodies” lies in space between them, causing them to orbit each other at a periodicity of 6.3 days. This doesn’t happen with the Earth and our own moon because the moon has only 1% of the Earth’s mass, and the center of gravity lies somewhere inside the Earth.

All of this is fine astrophysical commentary, until Ray moves out to the looney fringe. He remarks that there are probably plenty of double planetary systems out there in space (although Hubble hasn’t discovered any yet). And heeeere comes the weird part. Ray comments:

Nevertheless, there might be binary planets that are habitable. The consequences would be extraordinary. The planet where intelligent life first arose on would dominate the companion planet. One can imagine a “space race” to colonize the twin world — and no doubt subjugate whatever was living there. Travel and trade between the two worlds would become commonplace.

Wow! Be glad we don’t have a double planet. If you want the reap the rewards of Ray’s full wisdom, here’s the link:

Maybe the best part of this is that Ray recently wrote another article (see below) in which he complained that our notions of aliens are simply “lame” projections of humans (onto insects, or bugs, or crustaceans, or whatever…). Hmm…

Just to round out this post, if you’re having trouble remembering the names of the planets and their positions relative from the sun, here’s a mnemonic sentence that Jerry Roberts taught us in eighth-grade science at Eisenhower Junior High School:

“My very educated mother just served us nine pickles.”

Which led one bright bulb in the class to write, on a test, “The planets are, in order from the sun outwards:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pickles.”

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I am a science writer at the Max Delbrück Center for Molecular Medicine in Berlin, author of fiction and popular science books, an artist, and a professional musician who performs on the viola da gamba and Medieval and Renaissance stringed instruments. I edit manuscripts of all types and teach the full range of scientific communication skills. I am doing theoretical work in this subject - see for example

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