Solar Exploration

Earth is, as far as we know, the only place in the universe where life exists — a fact made possible by a rare combination of circumstances: liquid water covering most of the surface, a magnetic field that shields the atmosphere from solar wind, and an orbit sitting squarely in the Sun's habitable zone. Roughly 71% of the surface is ocean, giving Earth its recognizable blue appearance from space.

Earth's single large Moon is unusually massive relative to its parent planet compared to other moon-planet pairs in the solar system, and it plays an outsized role in Earth's habitability — stabilizing the planet's axial tilt over millions of years, which in turn keeps the climate relatively stable enough for complex life to evolve.

Earth's atmosphere is a thin, life-sustaining layer of mostly nitrogen and oxygen, held in place by gravity and protected from being stripped away by the solar wind thanks to a magnetic field generated deep within the planet's molten iron core. Geologically, Earth is the only planet in the solar system known to have active plate tectonics — its crust is broken into moving plates that recycle rock, build mountain ranges, and drive the carbon cycle that helps regulate long-term climate.