3 ms·
We've had proof of large rocky bodies for 4.5 billion years. MVEM. Also physical traces of the remains of the planer building, post dust cloud phase(asteroids/c
by geuis 17y ago
We've had proof of large rocky bodies for 4.5 billion years. MVEM. Also physical traces of the remains of the planer building, post dust cloud phase(asteroids/comets/impactor sites on every body in the system). Cosmology works under the theory that our local implementation of physical laws is the same elsewhere in the observable universe. What we are finding now at the level of exo planetary bodies is independent confirmation of the local phenomena we have already observed.
- run4yourlives 17y agoThere is theoretical proof and physical proof. The op is stating the former. Nobody has ever actually seen a physical body larger than Earth until now.
- hughprime 17y agoWe've had proof of large rocky bodies for 4.5 billion years By large, I mean significantly larger than Earth. We know about rocky bodies up to one Earth mass. We also know about low-density ice-gas bodies of 14 Earth masses or more. Bodies in between these two known types of planet, though, we're pretty ignorant about -- are they Earthlike or Uranuslike? Now, while N=1 makes for lousy statistics, we know that at least this one is Earthlike. We're actually still astonishingly ignorant about how planets form in the first place, so anything we can find out about the compositions of exoplanets is pretty valuable.