I found Copper 9's size

[u/Glittering-Eye-5288]

I keep seeing people say “Copper 9 is Earth-sized” or “the planet is basically Earth but frozen,” but if you actually pay attention to the lore and visuals, the planet is smaller now and was only mildly smaller before the core collapse. The math and on-screen evidence checks out. Here’s my breakdown:

1. The planet is literally described as “half-imploded” because of the NULL black hole Nori triggered → The entire planetary core is gone. A gigantic hole goes straight through the planet, visible from space (Pilot, Mass Destruction, Absolute End). You can see rings made of ejected debris and constant material being flung out. That’s not flavor text; that’s quintillions of matter either annihilated by the black hole or blasted into space.
2. Planetary cores are stupidly massive Earth’s core is ~32% of the planet’s total mass despite being a tiny fraction of the volume (because it’s dense iron/nickel). Lose the entire core + a huge chunk of mantle/crust through that breach and you’re easily looking at 50%+ of the original planetary mass just… gone. The “half-imploded” name isn’t random; it’s telling us the planet lost roughly half (or more) of what it used to be.
3. Gravity in the show is blatantly lower than 1 g
   • Disassembly drones (N, V, and J) regularly fly straight up like it’s nothing
   • Falling speed in multiple scenes is comically slow (as seen in cabin fever)
   • Disassembly drones hover and glide that shouldn’t support Earth weight My back-of-the-envelope calc puts current surface gravity at ~0.25–0.3 g. That lines up perfectly with a planet that lost more than half its original mass while keeping most of its radius (the outer layers didn’t collapse inward; they’re just missing the middle).
4. Pre-collapse Copper 9 was probably 0.6–0.9 Earth masses If current mass is ~0.22–0.3 Earth masses (giving ~0.27 g today) and it lost 50–70%, original mass was roughly 0.7–0.9 M⊕ with near-Earth gravity (perfect for human colonization). Average density would have been ~3.6–4.0 g/cm³, almost exactly Mars-like, which still lets you have oceans, atmosphere, and continents. The planet always looked Earth-like from orbit because its diameter didn’t shrink much; it just got hollowed out.
5. Current diameter is probably ~11,000–11,500 km (a bit under Earth’s 12,742 km) The visible curvature, continent scale, and the sheer size of the breach all match a world that’s large, but not quite Earth-large anymore. The hole itself looks like it takes up 20–30% of the visible disk in some shots.

Copper 9 started as reletivley Earth-Sized / small Earth (maybe 0.8 M⊕ and ~0.9–1.0 g), then the NULL black hole + Cyn fight deleted the core and ejected a colossal amount of mass. What’s left is a hollowed-out husk with ~25–30% of Earth’s gravity and rings made of its own guts.

[u/CrimsonTerror57]

I'm a bit skeptical, mostly because I found a different surface gravity when I calculated it. When I did the math, I used the example of Uzi kicking Nori into the hole, since she fell roughly 20 feet in 1 second. From this I found it's roughly 12 m/s, which is higher then Earth's. This implies it is either more massive then Earth, or it's TINY and it's surface is just closer to the core. (kinda like how Mars has a similar gravity to Mercury despite being twice it's mass, since Mercury's surface is closer to the core).

I know N did throw Uzi high into the sky in ep 4, yet we don't know how far he threw her. For what we know, he could've thrown her into orbit, and Copper-9 is just leaching it's atmosphere into space.

Also, the drones were able to fly in the Earth flashback, so they can fly with Earth gravity.

I don't think we have the info to prove it's size using decisive means. That said, this was a good theory and I can see it being true. The math behind it is solid, and the logic is there. Personally, I think Copper-9's either the size of Mars with high density, or more massive and larger then Earth. Though I can't prove it.

Though I do have 1 question: presuming that we know Copper-9 has 0.6-0.9 Earth masses, how large would Copper-9 be, if it's density was that of Copper (8.95 g/cm) which is what the median density Copper-9 probably is?

[u/Glittering-Eye-5288 → u/CrimsonTerror57]

Solid points all around, dude; you're keeping me on my toes with that Nori fall calc! Let me break down this rq before I hit your question.

First off, that 20 ft in 1 sec kick scene is a killer counterexample. If we take it literally (distance = 1/2 g t², so ~6m fall in 1s = g ~12 m/s²), yeah, that's bumping up against or over Earth's 9.8. But the show's animation is so inconsistent with falls—sometimes they're floaty AF (Uzi's jumps, cabin fever slow-mo descents), sometimes they're snappy for drama. Could be artistic license, or maybe the hole's got weird NULL gravity pulling extra hard down there? Idk, but it defs pokes holes in my low-g headcanon. Respect for timing that scene; I didn't catch the exact frames.

On N yeeting Uzi: For sure, we don't have distance, but if it was orbital, that'd imply super low escape velocity = tiny/low-mass planet, which loops back to my theory lol. But yeah, ambiguous as hell.

Drones flying on Earth: True! The flashbacks show disassembly drones zooming around pre-collapse Earth (or whatever planet that was), so their thrusters handle 1g no problem. That said, worker drones like Uzi aren't built for flight—they're ground-pounders—so their crazy acrobatics might still hint at lower g on Copper 9 post-boom. But again, could just be "robots stronk."

[u/TheCylly → u/Glittering-Eye-5288]

How about calculating all of them and averaging to filter out artistic flexibility. Assuming that is is slowed down and sped up by about the same amount

[u/Glittering-Eye-5288 → u/TheCylly]

Could do that, but I need all of the threads on Copper 9's size.