When worlds collide

In 1933, Philip Wylie and Edwin Balmer serialised a science fiction book, When Worlds Collide. They proposed that an orbiting pair of rogue planets was on its way to Earth on a hyperbolic trajectory, which our system would bend into an ellipse of period eighteenish months. The pair would then pass by Earth (and Luna) again, ousting them from our orbit; instead dumping its own smaller planet in our stead and then, I don't know - maybe going off to smash Mars.

Presumably Earth Two would inherit a highly elliptic orbit of her own. I don't know that the authors sorted out the Newton. They did, at least, figure out they could use the Orion Rocket as an Ark [UPDATE 3/14/21 - if you don't ask how to land it again]. I didn't read the book. I did see the 1951 movie... it stank. Melancholia wasn't good either. But anyway.

It occurred to me that something like this has happened only 70000 years ago. Scholz's Star (-system) whizzed by our Oort Cloud. If true that's close enough to be measured in Astronomical Units: 52000 times as far from our Sun as our Earth is.

Scholz's Star isn't much of a star. It is a red dwarf with a brown dwarf companion. We know it came by because it is (barely) a star, which can be seen (now) 20 light years away. UPDATE 8/15/22 And it probably didn't get all that close anyway; they're now talking 1.08 light-years 80 kya. NEXT

Gliese 710 is more relevant to my purpose here. It is a 0.6 solar-mass orange dwarf; it could well have its own planetary system. It will be coming within 14000 AU. Although we won't have to worry about this one for another 1,281,000 years.

I do not hold the 1.5 million year span encapsulating both Scholz and GJ 710 as a special span within the 4567 million years of our solar-system's existence. In fact, this span should be one of our quieter spans, given that we're not in the Galactic Ecliptic and that the rest of the Galaxy is winding down (I mean, until Andromeda crashes into us, but our personal system will be cooked by then). Given the proportion of stars, red-dwarfs, and rogue planets out there - not to mention the hyperbolides - it all leads one to wonder what else might have drifted by, not so visible.

And suppose a 1.5 solar-mass star rammed through here within, oh, 5000 AU millions of years back - with all its own retinue of large orbiting planets, and let's add a Proxima-class red dwarf. This has implications for Planet Nine. Maybe we had one. But it got stripped away.

UPDATE 12/7: Comins on Cerberon. We (Comins then, me now) hadn't constrained how often other stars might get here, nor how close they'd get to us. So I'll put a marker: we're all safe within 1000 AU of Sol, until Andromeda merges with us, by which point the Earth will be a radioactive dry husk anyway. Almost all planets this far from the Core are safe, however far that may be.