A changing planetOur World

Earth

Follow the planet from its formation through changing rocks, atmosphere, life and climate.

Subject guide · scope, chapters & sources ↗

A selective planetary history, with rounded geological ages and existing life chapters reused. Formation models and ancient climates retain uncertainty. The modern endpoint is NASA’s temperature record through 2025, reported in February 2026.

Official Earth time scaleSelect an eon on the road to reveal its eras.ICS 2026/06 ↗

c. 4.54 billion years agoSolar System

Earth takes shape

Rock and metal gather around the young Sun.

Dark, crusted Allende meteorite fragment. — Jon Taylor · CC BY-SA 2.0

c. 4.5 billion years agoEarth–Moon system

An impact origin for the Moon

A violent encounter helps shape the Earth–Moon system.

Illustration of a large body colliding with the young Earth. — NASA · NASA editorial media-use permission

c. 4.4 billion years agoPresent-day Australia

Tiny crystals preserve early Earth

An Australian zircon retains an exceptionally ancient record.

A light-colored rock specimen supported inside a glass museum case. — Mike Peel (www.mikepeel.net) · CC BY-SA 4.0

At least 3.5 billion years agoEarth

Microbial life leaves evidence

Ancient rocks preserve traces of a living planet.

Layered Paleoarchean stromatolite specimen. — Didier Descouens · CC BY-SA 4.0

c. 2.4 billion years agoAtmosphere & oceans

Oxygen transforms the atmosphere

Microbial photosynthesis changes the chemistry of Earth.

Blue-grey banded iron-formation specimen on a museum stand. — Kjoonlee · CC BY 4.0

c. 1.8 billion years agoEarth

Complex cells diversify

Cells with internal structures establish a new branch of life.

Light-microscope view of modern Paramecium caudatum cells. — Fritzmann2002 · CC BY-SA 4.0

c. 720–635 million years agoEarth; evidence in present-day Colorado

Ice reaches ancient tropical regions

Geological evidence points to severe glaciation.

c. 300–200 million years agoPangaea; future Atlantic margins

Continents join in Pangaea

Land now separated by the Atlantic belongs to one continent.

c. 66 million years agoGlobal

An extinction reshapes the living world

Non-avian dinosaurs disappear, but some bird lineages survive.

Grey boundary layer between reddish and yellowish tilted rock beds at Zumaia. — M. Schaap · CC BY-SA 4.0

2025Global

A measured record of a warmer planet

2023, 2024 and 2025 form NASA’s three warmest recorded years.