What Would Happen If Gilly Hit Kerbin?

[CG_Kerbin]

.... You have to ask this question in a game with Jebidiah Kerman? He just wanted to fly a moon... Just a little one.

The little jeb that could *Awww*

[Dres]

I've been reading this, and I have a question about some calculations in this thread. As most of you know, KSP Planets are *Ahem* A Little More dense than real planets. Kerbin has a density many times denser than osmium, the densest element in the universe. Would the density have and effect on the impact at all? From what I've seen, people have been using sedimentary rock as the material impacted on the surface of kerbin, when it's clearly not.

Edited March 28, 2015 by Dres

[lajoswinkler]

It would obliterate Kerbin's surface and cause disastrous tectonic disturbance at the antipode. Lots of the lithosphere would be peeled off and huge lava seas would form. All water would evaporate and form a global dense white cloud, making it look like a small Venus from orbit.

[Renegrade]

I've been reading this, and I have a question about some calculations in this thread. As most of you know, KSP Planets are *Ahem* A Little More dense than real planets. Kerbin has a density many times denser than osmium, the densest element in the universe. Would the density have and effect on the impact at all? From what I've seen, people have been using sedimentary rock as the material impacted, when it's clearly not.

Asteroids are believed to be between 1.4-5 t/m³ (the same number in g/cm³ if one prefers), and Gilly is around 13.5 t/m³ (slightly higher than lead); it's indeed a large and scary rock. Well, ball of lead. Also, it's 13km in radius, whereas impactors seem to be measured in diameter for whatever reason, so it can be double the size (eight times the volume) if that isn't taken into account.

And yeah, density would have a.... massive *cough* effect on impacts. If you dropped a soap bubble 26km across on Kerbin, nothing would happen, whereas a neutron star 26km across would probably shatter Kerbin like a wineglass being hit by a designated batter.

[Armchair Rocket Scientist]

And yeah, density would have a.... massive *cough* effect on impacts. If you dropped a soap bubble 26km across on Kerbin, nothing would happen, whereas a neutron star 26km across would probably shatter Kerbin like a wineglass being hit by a designated batter.

You couldn't even call an interaction between a planet and a neutron star an "impact." First of all, the neutron star will by more massive than the sun, so it's more like the planet falls onto the neutron star.

Second, the planet will be torn apart by tidal forces long before reaching the surface. According to this: http://en.wikipedia.org/wiki/Roche_limit#Rigid-satellite_calculation, given an Earthlike planet and a neutron star of 2 solar masses, the planet will disintegrate over 600,000 km from the neutron star - before it even reaches the orbit of the moon. A combination of heat released in this process and radiation from the star will turn the planet into a streamer of liquid or gaseous debris, which may turn into plasma. It's possible that the remnants of any atmosphere will be excited to absurd temperatures and thrown into space. However, the process happens extremely quickly; assuming we start the planet out stationary at the Roche limit and ignoring relativistic effects, it would take less than an hour for it to reach the surface.

When the "head" of the plasma stream contacts the neutron star surface, there will likely be a huge explosion which vaporizes any material that was still solid or liquid. Eventually, all the planet's material will either end up in orbit around the neutron star, flying off into space as highly energetic plasma, or absorbed by it (meaning that all the protons and electrons of the atoms making up the planet are transformed into neutrons).