Rocketpunk Manifesto has never claimed to be a space news blog, so I make no apology for being the last space blog in the known universe to mention last week's report of a planet found orbiting both components of a double star. (There is no indication - yet - of more than one planet in this system; see illo note at the end of this post.)
I will apologize for slower posting of late, the excuse being a couple of new work gigs I'm still breaking in.
But back to the world of two suns. The interesting thing about this - apart from the discovery itself - is that when I was growing up, and for long afterwards, the standard wise advice for any SF writer aiming for a speck of hardness was to avoid binary-star planets like the plague.
Any such planet was liable to be hurled out of its birth system. Even more to the point it was unlikely to form in the first place, disrupted before birth by the processes that formed a binary star in the first place. Which meant that in hard SF perspective, any planet of a binary might as well be 1930s baroque, with the blue sun rising as the red sun was sitting and the orange sun was at midafternoon.
Not for the first time - and surely not for the last - elegant inference has been trumped by observation.
Certainly not for the first time in the history of extrasolar planet discoveries. The first such worlds to be found, in 1993, were so hard to wrap our collective mind around - three planets orbiting a pulsar - that they were not fully acknowledged as 'real' planets.
Then came 51 Pegasi b, in 1995. The star is suitably sunlike, but no one expected a planet comparable in mass to Jupiter to be orbiting several times closer in than Mercury. And basically things have stayed weird ever since.
Before 1995, I'd venture that most people (who thought about it at all) expected more or less the same thing I did. Extrasolar planetary systems, when we found them, would mostly have the same overall organization as the Solar System. They'd have some rocky terrestrial inner planets between about 0.3 and 3 AU, and some gas giants out beyond the 'snow line.' Beyond the gas giants would be nothing much.
Details would vary, of course. Some systems might have only two or three planets, others well over a dozen. A few with planets bigger than Jupiter - even approaching brown-dwarf mass - and other systems with only Saturns or Neptunes. Most of these planets, big and small, would be on near-circular orbits, in striking contrast to the highly eccentric orbits typical of binary and multiple stars. The spacing of their orbits would likely be suggestive of 'Bode's law.'
By the current more or less official count of the Paris Observatory there are now 687 confirmed extrasolar planets. And precisely none of them are in systems with an overall architecture like I just described.
As I have noted here before, this is (probably) at least in part an artifact of observational 'selection effects.' Most of those 687 planets have been discovered by techniques that have a technical bias in favor of large planets close to the parent star. Indeed, a duplicate of the Solar System would be only at the threshold of detectability.
All the same it is starting to be just a little bit odd that so few known extrasolar planetary systems are even kinda sorta like the Solar System. Looking at the Paris Observatory website, there is just a hint that planets are more common around 5 AU - Jupiter distance - than around 4 AU or 6 AU. Some even have fairly circular orbits.
But all in all, the planets and planetary systems we have been finding have amazingly little in common with the ones we expected.
I don't want to draw very many large conclusions from this, except perhaps that 'large conclusions' are likely to be wrong. In particular, note that this particular discussion is entirely about the physical (and observational) facts about astronomical bodies, not about future human societies that might investigate those worlds, or seek to do more than investigate them.
But they are interesting, in themselves and for their possible place in human affairs, SFnal or otherwise.
The image comes from Space.com - but just to keep things interesting, it illustrates a discovery made last fall, not last week.