A little thought exercise about space objects and earth collisions

[RainDreamer]

What kind of space object would be able to pierce right through the earth? The aftermath of such collision is not a concern here, earth could very well shatter from the shockwaves, but at the moment of impact, the object must go right through from one end to another of earth. Can be any shape and size, made from any material. What kind of mass would it have? What kind of speed would it have?

This question came after a discussion between a friend of mine and I about asteroids and what possibly happen when one collide to earth. Then we go all funny and imagine impossible things like the question above.

[magnemoe]

Neutrinos does it all the time, they hardly interact with anything.

A small black hole would pass straight trough. probably the same for neutronium from neutron stars however its unstable in small amounts.

If the black hole is small you would get an explosion at impact and at exit point but this would be smaller than an asteroid of the same weight as it just pass trough.

[How2FoldSoup]

Obligatory https://what-if.xkcd.com/20/

[K^2]

In order to pass through intact, it has to be neutron matter or denser.

[LLlAMnYP]

Can't provide the exact link, but there was a similar discussion here (the question was "how fast do you need to go to pass through the earth intact?") with the general conclusion, that any conventional object would not penetrate the earth deeper and deeper, but instead just make a bigger and bigger *splat!* with increasing speed/mass. Otherwise, yes, high-density, exotic stuff, black holes, etc. Those would pass through the earth not too hindered.