Nevertheless, jossing isn't just something that fans of entertainment products have to worry about. It's an issue of the real world as well - particularly something that science fiction writers have grappled with for decades. Think back to the Mars of Edgar Rice Burroughs, the solar system as developed by Leigh Brackett, or the jungle-like Venus which appeared again and again in the literature until the 1960s. When Mariner 4 made the first successful flyby of Mars in 1965, it revealed a red, dead world with no canals, no Martian princesses, no crumbling empires, and effectively jossed almost every fictional thing that had been written about Mars up to that point. It was due in large part to this and subsequent jossing, made possible by the robotic exploration of the solar system in the latter half of the 20th century, that sf writers began packing up in earnest and moving out into the greater galaxy.
For a while, that was perfectly fine. You could build your planetary system around Tau Ceti or Alpha Centauri or wherever else, and you could be fairly confident that you wouldn't experience another "Mars correction," right? Hell, even today you could argue that holds true, but the way I see it, the situation is analogous to the time when Mariner 4 was still in flight - it hasn't revealed anything yet, but you know it's going to do so before too much longer.
An artist's impression of some of the planets known to orbit the star 55 Cancri A. This image from NASA is in the public domain.
The current breed of astronomers are something else - for the first time in history, they've been pinpointing planets orbiting other stars. Over the last fifteen years, hundreds of exoplanets have been detected, and the degree of detail that we can determine about these worlds across the light-years is astonishing when you consider how limited the detection methods really are; sometimes they're measuring minute diminutions in brightness from the transit of an exoplanet across its star, sometimes they're measuring the "wobble" produced as an orbiting planet tugs its star just slightly this way and then the other, and sometimes they use even more exotic methods.
This new knowledge provides a fertile field for speculation. Allen Steele was one of the first authors to get into this in a major way, with his series of books and short stories about Coyote, the fictional habitable moon of the very real 47 Ursae Majoris b, a gas giant that was one of the earliest exoplanets to be discovered. For my part, the temptation to work in a similar manner is almost unavoidable - the desire to base my work on known and measured reality to the greatest possible extent is a strong one.
For a while, the 55 Cancri system looked to be a good bet. One of its larger planets, of a size that it could easily be a small gas giant, was known to orbit in its star's habitable zone - which could make life as we know it possible on a moon of this planet. I've been running with that for the past little while, sketching out background details and information for Esperanza, such a theoretical habitable moon.
But then - gnashing of teeth! A few days ago, Phil Plait linked to a new scientific paper dealing with 55 Cancri f, and according to the latest measurements, while it does orbit within the star's habitable zone... it doesn't do so for all of its orbit. f has something of an elliptical orbit, and so actually leaves the habitable zone for about a third of its orbit. The expected temperatures for a planet in that orbit don't leave me much room that I can feel I can work with.
So... back to the drawing board. I find myself wondering if I should just invent a star system, get it over with and build it precisely to my specifications; that would, however, defeat the purpose of building it on reality.