Earth: a world of living systems
Earth’s atmosphere, oceans, interior, and biosphere exchange energy and materials. Its distance from the Sun and atmospheric conditions allow widespread liquid water at the surface.
A planet’s habitability cannot be decided from distance alone. Air pressure, composition, temperature, and available energy matter too. No confirmed discovery of life elsewhere means an unanswered question, not proof that Earth is alone.
Wonder about this
Does finding a planet like Earth prove it has life?
A science clue
No. Scientists need evidence of life; size or location alone is not enough.