The solar system began to form about 4.6 billion years ago - 9.2 billion years after the Big Bang. Scientists think that its formation was triggered by the shockwave from a nearby supernova - an exploding star. Then, a small part of a giant nebula collapsed under the influence of its gravity into a protoplanetary disk of dust and gas. Most of the disk’s material was concentrated in the centre of this cloud, forming the sun. In the outer parts of the rotating disk, clumps of material collided and stuck together, eventually forming larger objects that became the planets in our solar system.
Planet Earth started life as a sphere of molten rock. A collision with another large object caused a large chunk of the young Earth to be thrown into space, which later became our moon.
Over several hundred million years, the Earth cooled and a solid crust formed on its surface, together with the continental plates and an early atmosphere. Liquid water gathered on the surface. Scientists think this water came from condensing steam from rocks that released gases, and from the impact of comets that carried ice from the outer parts of our solar system.
The earliest evidence of life on Earth dates back to about 3.8 billion years ago.
Then, about 3 billion years ago, photosynthesis started to enrich the Earth’s atmosphere with oxygen.
Finally, about 600 million years ago, the first multicellular organisms developed, starting the complex process of evolution that eventually led to the emergence of all species on Earth.