[mr_mitm]

It's like astronomer talking about metals. By which they mean everything that's not hydrogen or helium.

[JumpCrisscross]

> like astronomer talking about metals

This is particular to stellar astrophysics. Astronomers studying asteroids maintain the conventional definition.

[kortex]

To their credit, I remember something about basically every element ionizes to some extent in space, thus exhibiting the "sea of electrons" behavior characteristic of metals.