With the excitement surrounding the potential “discovery” of planet 9, I just want to caution people who want to use this as the basis of a story, especially doomsday stories. There have been a number of sensationalist articles about the danger it poses: to wit that it could destroy all life on earth any day now as claimed by, for example, a NYP article. Utter nonsense. So any sci-fi writers out there, please be careful if you use this as the basis of a story.
The argument goes that it might knock Kuiper belt objects out of orbit, which then become a hail of comets and one could slam into the Earth and cause a major extinction event. So far as that goes, no problem. However, there are problems with the way some people are writing about it.
- The planet hasn’t been discovered yet. There is strong evidence that it might exist. (3 sigma is the value I’ve seen, not nearly enough for “proof”; not a smoking gun.) That is more than enough evidence to hunt for the planet, but no one has found it yet. We don’t even know where it “should” be. We just have a very large region of space that it might be. For speculative stories set well into the future, that’s not a problem. That is a problem if you want (or for a character) to actually scream that the sky is falling now.
- Extinction events in the past (and any future ones like those) have not wiped out all life as the NYP is claiming. The worst extinction event (the Permian-Triassic event; not the one that killed the dinosaurs) killed 90 to 96% of all species. That’s a lot (and would include us in all likelihood) but not all life. If you want to wipe out all life in your story, then find a different cause. Otherwise, if you categorically claim all life will be/was killed, I, for one, would stop reading your story right there and then. You clearly don’t know what you’re talking about.
- Next month? Apparently several doomsayers are claiming this. You only have to do a Google search to find them. I have to laugh and snort in derision. We don’t even yet know where this hypothetical planet is (not even where on it’s conjectured orbit it might be). We have eliminated a lot of possibilities (the last I saw, about 90% of them), but not pinned it down. And for writers, the important thing is that even if it did start knocking Oort cloud objects out of their orbits right now, we’d still have years before there was any threat, and we’d almost certainly see the resulting hail of comets years – decades – before one actually hit us. The Earth is very small, and these comets are even smaller, so the overwhelming chance is that they would orbit the sun many times before one actually hit the Earth. If you want any comet to hit the Earth on the first pass, you might as well have your blind hero fire a gun and bounce the bullet off a speeding car to hit the dancing enemy’s one and only weakness in his pinky finger.
- Please get your facts straight. The Oort cloud (not the Kuiper belt) is much more likely to be the source of the problem. Most long-peroidicity comets come from the Oort cloud. Moreover, by all accounts the planet 9’s orbit is not in the ecliptic (that’s important, and if you don’t know what the ecliptic is, you need to do some reading before writing about the solar system) and its perihelion is 200 AU from the sun while the outer edge of the Kuiper belt is about 55 AU.
- Finally, if you need a doomsday scenario, consider all the possibilities. Comets and asteroids are sexy these days, but many of the extinction events on Earth had nothing to do with impacts. Some (the K-T event for example) probably did, but even for that one there is good evidence that it wasn’t so simple as just that. There have been ~25 identified major extinction events (5 really big ones but 100s of minor ones) but only 2 or 3 of those (only 1 of the big ones) exhibit evidence of collisions, while there is strong evidence for other causes and those could be more useful for your story. See for example https://en.wikipedia.org/wiki/Extinction_event but even better, find several (to get differing opinions) books on the subject or talk to experts.
- Don’t be sucked into one of the cyclic theories of mass-extinction. That’s been over-used and there are other possibilities that could be useful for your story. And frankly, even though many writers (including some big names) have jumped onto this bandwagon, in reality there is still a lot of debate and the jury is still out. Unlike some fields (climate change for example) there isn’t general consensus among most of the experts.