Oooo, good question. What if it were traveling, relatively, at a fair percentage of C? Say 80 or 90%? What if it went not straight through the center, but say 30% off of center? Would any mass make a complete pass through, at that velocity? It'd be about 23% more dense from relativity, but countless YouTube videos about gun ammunition has taught me that velocity is the biggest factor in armor penetration. Would it blow a huge plume of plasma out the other side?
Dude, you just made this no doubt question far, far more interesting!
Fascinating. Lets say at 90% the planet spends 1 second inside the sun. Doesn’t seem like enough to melt the whole thing so it just keeps going, just a lot smaller. The core of the sun tried its best to push it back but gets pierced and the fusion reaction stops. Star killer??
Edit: I was off by a big order of magnitude, see my reply to this comments reply.
No. You are also forgetting the density of the sun increases with depth. For instance, if it's heading for the core - the solar core is about 155g/cm^3. Where as earth is 5.5g/cm3.
Essentially, going 0.9C is going to impact the sun, and we can say the incoming earth object is going to classically hit with 4.9*10^24 J.
At this size and and energy, we compare it to the rest energy of the entire sun (this isn't how we would actually do it) but the sun has a total resting mass energy equivalence of like 1.8x10^41 J.
The energy of the earth like object impacting the sun is 0.000000000000000027%.
The sun effectively doesn't even know it happened.
Another comparison here. If a human was just made of ballistics gel, weight for weight, meaning no vital organs or anything, a 10g round would hit a target it 1/9000 the side of.
Earth, hitting the sun would be like something 1/800000 this size of.
Oh shit my lunesta kicked in. Someone better double check my numbers