A 4.5 billion-year-old meteorite at the Royal Observatory in Greenwich. It is one of the oldest meteorites on the planet.
The Gibeon Meteorite formed around the same time as the Sun and the Earth, during the Hadean era. It was part of an asteroid before it fell to Earth in what is now South Africa. It was discovered by the Nama people and used to make tools and weapons. Samples of the meteorite were collected by an Englishman in 1836 and sent to London.
The Hadean is technically not a geological period, as the only rocks on Earth this old are meteorites. During this time, the Solar System was forming within an accretion disc – a large cloud of gas and dust around the sun. The gas and dust probably came from a supernova.
The sun formed within the accretion disc, and gravitational compaction forced it to shrink in on itself. It began to undergo nuclear fusion, which meant that it gave off light and heat.
Other surrounding particles began to coalesce (due to gravity) into larger lumps called planetisimals. These began to collect and form planets. “Left-over” material formed asteroids and comets.
When large planetisimals collide, they reduce a lot of heat. Therefore Earth (and other planets) started out as very hot.
Sometime during the first 800 million years of its history, the surface of the Earth changed from liquid to solid. Earth's geological history began once solid rocks formed. The oldest meteorites and lunar rocks are about 4.5 billion years old, but the oldest-known Earth rocks are about 3.8 billion years old.
