earth
Earth has no birth certificate. Its own oldest rocks were destroyed by the planet it belongs to, so the age of the Earth had to be read from objects that never changed — and that indirection is the first thing worth understanding about deep time.
About: Earth · Accretion · Planetary differentiation · Radiometric dating
Earth formed by the falling together and compression of cosmic debris — a process that converted gravitational energy into heat and left the young planet hot enough to separate into layers.[1]
None of that is recorded in Earth’s rocks. Plate tectonics has recycled and destroyed the oldest crust, and no rock in its original primordial state has ever been found. The planet’s own archive does not reach back to its formation.[1]
Because Earth cannot date itself, the number comes from meteorites. Radiometric dating of more than seventy meteorites of different types places the formation of the Solar System between 4.53 and 4.58 billion years ago.[1]
The best age for the Earth, 4.54 billion years, follows from lead isotope ratios in iron meteorites, on the assumption that Earth and the other solid bodies of the Solar System formed at the same time. It is an inference resting on that assumption, and Lithoen records it as one.[1]
The oldest rocks yet found on Earth — the Acasta Gneisses of northwestern Canada — are 4.03 billion years old, and single zircon crystals preserved inside younger sedimentary rocks in Western Australia reach 4.3 billion years. These set a floor, not a date of birth.[1,2]
They also say something about what came before them. Rocks older than 3.5 billion years occur on every continent, and they are not a primordial crust: they are lava flows and sediments laid down in shallow water. Ordinary surface processes were already running. Earth history began well before the oldest surviving page of it.[1]
Accretion left the planet with a store of heat, and enough of it survives that Earth’s primordial heat supply has not yet been exhausted. That inherited warmth, together with heat still being produced by radioactive decay, is what keeps the interior in motion today.[1,2]
Differentiation was the first consequence: dense metal sank, lighter silicate rose, and the planet arranged itself into a metallic core beneath a stony mantle and crust.[1]
Often said
“The age of the Earth was measured by dating the oldest rock on Earth.”
What the evidence supports
The oldest Earth rocks give a minimum age for surviving crust, not the age of the planet. Radiometric dating records the last time a sample was melted or disturbed enough to reset it, and plate tectonics has destroyed everything older. The 4.54-billion-year figure comes from meteorites.
Supporting records: earth-no-direct-age · radiometric-what-is-dated · earth-age
Bracketed references link to the structured entity records whose claims support each paragraph. Last updated 2026-09-06.