Hi Allynh, Grey Cloud, GaryN,
Here's a take by a mathematician, you can always trust someone who can do the math....
A hypothetical with a mirror earth called Htrae having a near miss with earth,
the person who wrote this scenario on this 'askamathematician.com' website has imagined a situation with Earth and another hypothetical planet nearly touching, the two planets orbiting in opposite directions, and (doesn't mention daily spin, or moon, or magnetosphere)....
Earth is grazed by an equal size planet:
"A near miss is a lot less flashy, but you really wouldn’t want to be around for that either. When you’re between two equal masses, you’re pulled equally by both. You may be standing on the surface of Earth, but most of it is still a long way away (about 4,000 miles on average). So if Htrae’s surface was within spitting distance, then you’d be about 4,000 miles from most of it as well. Nothing on the surface of Earth has any special “Earth-gravity-solidarity”, so if you were “lucky” enough to be standing right under Htrae as it passed overhead, you’d find yourself in nearly zero gravity."
"Of course, there’s nothing special about stuff that’s on the surface either. The surface itself would also start floating around, and the local atmosphere would certainly take the opportunity to wander off. On a large scale this is described by the planets being well within each others’ Roche limit, which means that they literally just kinda fall apart. It’s not just that the region between the planets is in free fall, it’s that halfway around the worlds gravity will suddenly be pointing sideways quite a bit. So, what does a land-slide the size of a planet look like? From a distance it’s likely to be amazing, but you’re gonna want that distance to be pretty big."
"Even a near miss, with the planets never quite coming into contact, does a colossal amount of damage. There would be a cloud of debris between and orbiting around both planets (or rather around both “roiling molten masses”) as well as long streamers of what used to be ocean, crust, and mantle extending between them as they move apart. This has never been seen on a planetary scale, since all the things doing the impacting these days barely have their own gravity. <...>
<...>All of the damage and scrambling that Earth and Htrae did do each other took energy. That energy is taken mostly from the kinetic energy, so after a near miss the average speed of the two planets would be less than it was before.
http://www.askamathematician.com/2013/1 ... the-earth/
So my take would be, what would happen if an Venus size planet passed in the same direction, from an orbit further out towards Jupiter, quite far away from the Earth, with something like 80,000 km to 100,000 km between them?
Just far enough away that assuming each planet had much denser atmospheres in the past, Earth had a thicker atmosphere to help support the giant dinosaurs and such, the middle of the two magnetospheres passed through each other, (the top of earth's current magnetosphere is approx 65,000 km high), the two magnetospheres interact with violent electric discharges, both planets experience violent vulcanism, Venus steals Earth's excess atmosphere, the event slows Venus' rotation and leaves Venus in retrograde motion, but still orbiting the Sun in a modified orbit, the close call pulling Venus closer to the sun, so after passing the sun and the Earth closer a couple of times the Earth and Venus' orbits gradually become more stable due to resonant effects... the interaction leaving Venus very hot and with a huge CO2 and sulphuric acid atmosphere, the earth's crust is fractured and moved in some places, maybe the whole crust moves relative to the iron core, heating the magma in the earth's molten core, the whole North American plate shifted westward a bit for example... huge tides slosh around, creating huge deposits of sand, and mud and smashed up vegetation... this would be a definitely catastrophic event, vast majority of animals and species on Earth is killed, leaves lots of smashed up animals and plant matter to eventually become coal and oil, covered in sediment, maybe there was another body involved, like Mars...
I found that none of this is forbidden by celestial orbital mechanics, the Ransom Hoffee orbits for one describe a similar set of events, the recent proving of gravity assist moves with space probes show nothing like this is impossible, (there's a set of nine animated gravity assist orbital manouvres illustrated down the page a bit):
Discussion of Velikovsky's proposed events, and the orbits involved:
Haha, makes me wonder if 'Planet9' was the missing fourth body....