Starlight Glimmer wrote:
Starlight Glimmer wrote:
What if Theia hit Venus instead of Earth?
As far as I know, a similar sized object did strike Venus, but at a steep angle. The impact slowed it's rotation, acting as a brake, effectively "killing" the planet.
What if it didn't hit and became captured?
That's a bit of a hypothetical scenario, but those are often the most entertaining! Let's see what needs to happen for the Venus impactor to become captured. Assuming the impactor was the same size and mass as Mars and orbited the Sun near the L4 point of Venus, you can deduce the following: Any approach between the two worlds would result in a collision at high velocities, radical orbit migration or an elliptical binary orbit.
Let's look at what can happen in all three scenarios. Assuming the two worlds collided, depending on the exact angle and speed of impact, the event could end with the two bodies being a) pulverized, leaving only small bodies, b) destroyed, leaving one or two large bodies and a belt of small-to-medium asteroids or dwarf planets, c) coalesced, leaving behind a single, pretty massive body and possibly a large moon with up to 4% of the host planet's mass (this also accounts for when a newly formed moon of varying mass spirals into the planet). This collision would happen at pretty high velocities due to the mass of both worlds and their mutual separation. If we assume the worlds miss each other completely, an orbital migration is pretty likely from their starting position. Assuming the two bodies come very close to each other, their mutual gravitational attraction would fling them in opposite directions and greatly alter their inclination, ellipticity and semimajor axis.
The least likely scenario is that you'll end up with a system of two distinct tidally locked planets orbiting a central barycenter. This system would be easy to disrupt, and the bodies would most likely be in elliptical orbits with relation to the barycenter. Due to the masses involved, and the proximity to the Sun, this is the least likely option. In the off chance it DID become captured, it would cause large tides and would lock Venus into a short tidal rotational period (since a long period would increase the chance the bodies would separate again due to outside influences). Depending on the exact formation of this system, the two bodies could slowly approach one another until they collide, again resulting in one of the above.
Those are some off-the-bat estimates and I'm not exactly an expert, but that's how I can see it going, at least roughly.