Why Earth is perfect for life: Study reveals chemical secrets
Turns out, just having water and oxygen isn't enough for a planet to support life.
A new study from ETH Zurich found that rocky planets need a "just right" amount of oxygen during their formation—otherwise, they lose key elements like phosphorus and nitrogen.
Earth fits perfectly into this rare sweet spot, called the "chemical Goldilocks zone."
The right balance of elements
If there's too little oxygen, phosphorus (needed for DNA and cell energy) sinks into the core.
Too much oxygen keeps phosphorus but lets nitrogen (important for proteins) escape into space.
Only a middle level of oxygen keeps both elements where life can actually use them.
Why Mars can't support life
Planets like Mars miss this balance—they have too much phosphorus and not enough nitrogen.
Because of these strict chemical rules, only about 1% of planets might really be able to support life.
So if we're searching for habitable worlds, focusing on planets around Sun-like stars is probably our best bet.