They just have a very different take on some things, because their way of looking at the universe is different from how we look at earth.
The electronic structure of an element greatly influences its chemical behavior, so elements in the same group tend to be chemically similar. However, hydrogen is a bit of an odd-ball as group 1 elements go.
Sure, the table has mostly metals but there are a lot of gases.
Maybe metal was not the best word for that, but having word for "all elements except hydrogen and helium" is useful in astronomy
Astronomers presumably mostly think about matter in the form of a star, in which presumably all the hydrogen and helium would be in some sort of plasma state, and perhaps all the “metals” would be too.
I think it would be “absurd” for astronomers to change this because people who aren’t scientists get confused.
The reason astronomers use “metallicity” this way is largely historical: (chemical) metals are not as prevalent in stars as non-metallic elements like carbon and nitrogen, but they are much easier to detect in spectral analysis. So historically the “metallicity” of a star really did refer to the heavy metal content (generally Fe), and considering the physical processes involved it’s not unreasonable to extend this to all non-H/He elements in the star. I think it would be “absurd” for astronomers to change this because people who aren’t scientists get confused.
My bad yo. Please accept my humble apology in not knowing the historical signifacance of something. I'll be doing my masters in 2022/23, biochemistry/microbiology.
I really should have been a bird watcher instead.
Who cares about plant proteins anyway? That's not science at all.
So, really hydrogen, helium, and everything else is a perfectly reasonable classification as everything else acts the same outside of fusion.
At low pressures, it looks like as little as 15 Kelvin is enough to make Neon a gas.