The universe began with the Big Bang. Below is a brief historical overview of key events, including the time the first stars burned, when the Milky Way gave birth to its first planets, and the fundamental factors that led to the emergence of life on Earth.
13.77 BILLION YEARS AGO: The Big Bang and the Formation of the Universe
13.65 BILLION YEARS AGO: The formation of the first stars in the universe.
13.2 BILLION YEARS AGO: The first dwarf galaxies form.
13.17 BILLION YEARS AGO: The first gamma-ray burst (GRB 090423).
12.60 BILLION YEARS AGO: The Milky Way galaxy forms.
11.50 BILLION YEARS AGO: The first potentially habitable planet is Kapteyn B.
This planet is the first known world at a distance where liquid water can exist on its surface.
10.5 BILLION YEARS AGO: The first stars contain high concentrations of metallic elements such as oxygen, iron, nickel, silicon, copper, aluminum, carbon, calcium, and sodium.
9 BILLION YEARS AGO: The oldest known evidence of dark energy. Dark energy is responsible for the accelerating expansion of the universe over the last 5 billion years.
7.5 BILLION YEARS AGO: The star Arcturus forms. Today, it is known as the fourth brightest star in the sky.
6.4 BILLION YEARS AGO: Earth-like planets become common.
6 BILLION YEARS AGO: The Age of Dark Energy begins. Dark energy begins to accelerate the expansion of the universe.
5.5 BILLION YEARS AGO: The Milky Way transforms into a spiral galaxy. Today, it is a barred spiral galaxy.
4.57 BILLION YEARS AGO: The Sun forms.
4.56 BILLION YEARS AGO: Earth forms.
Earth forms during the formation of the protoplanetary disk that will give rise to today's planets.
4.53 BILLION YEARS AGO: The Moon forms.
4.40 BILLION YEARS AGO: The first oceans form.
4.4 BILLION YEARS AGO: The first minerals form. The first minerals begin to form on Earth.
4.2 BILLION YEARS AGO: Life forms on Earth. The emergence of life on Earth occurs. Earth becomes a planet stable enough to support permanent life 4.2 billion years ago. Phylogenetics begins with the evolution of the first life forms.
4.10 BILLION YEARS AGO: The first rocks begin to form on Earth.
3.9 BILLION YEARS AGO: Evolution begins with the formation of RNA and DNA.
3.8 BILLION YEARS AGO: The first iron deposits form in the Earth's crust.
3.7 BILLION YEARS AGO: The first biologically derived graphene forms.
3.60 BILLION YEARS AGO: The formation of the Valbaara supercontinent.
3.5 BILLION YEARS AGO: The first cyanobacteria fossils. These bacteria are organisms that feed on cyanide.
3.30 BILLION YEARS AGO: The first mountains on Earth appear as a result of continental drift and collision.
3.10 BILLION YEARS AGO: First Photosynthesis. During this period, the first oxygen-free photosynthesis process emerges in bacteria.
3.10 BILLION YEARS AGO: Living things emerge on land. The first bacteria appear on land.
3 BILLION YEARS AGO: True photosynthesis emerges.
2.7 BILLION YEARS AGO: First eukaryotes. Eukaryotes are the first cells to have a nuclear membrane.
2.6 BILLION YEARS AGO: The oldest known carbonate deposits and limestone begin to form.
2.5 BILLION YEARS AGO: Continental Drift as we know it and today's tectonic plates begin to form.
2.5 BILLION YEARS AGO: The Age of Oxygenation. Cyanobacteria begin to release oxygen into the Earth's atmosphere.
2.22 BILLION YEARS AGO: Atmospheric Oxygen Level Reaches 1 Percent.
2.1 BILLION YEARS AGO: The earliest known multicellular organisms emerge from the fusion of eukaryotes.
2 BILLION YEARS AGO: The first multicellular organisms become widespread.
1.9 BILLION YEARS AGO: Atmospheric oxygen content is 15 percent.
1.85 BILLION YEARS AGO: The ancestors of viruses and antibodies form.
1.5 BILLION YEARS AGO: The emergence of plants.
1.25 BILLION YEARS AGO: Fungi emerge on land as spore-reproducing organisms that are neither animals nor plants.
1.05 BILLION YEARS AGO: The first yellow-green algae
320 MILLION YEARS AGO: The first reptiles
280 MILLION YEARS AGO: The first insects. Insects
275 MILLION YEARS AGO: The ancestors of mammals. These creatures were the first to walk upright on all fours.
250 MILLION YEARS AGO: The Sirius Binary Star System forms.
231 MILLION YEARS AGO: The First Dinosaurs
225 MILLION YEARS AGO: The First Mammals
220 MILLION YEARS AGO: The First Turtles
2.25 MILLION YEARS AGO: The human species, Homo habilis, appears. Homo habilis is the first subspecies to use tools.
1.7 MILLION YEARS AGO: Homo erectus and the migrations. This species spread from Africa to Asia, inhabiting a wide geographical area. However, it became extinct with the arrival of Homo sapiens in India.
1.5 MILLION YEARS AGO: Homo erectus begins to use fire in a controlled manner.
1.2 MILLION YEARS AGO: Homo antecessor emerges.
600,000 YEARS AGO: Homo heidelbergensis.
This species is one of the first subspecies to explore the concepts of clothing and death.
250,000 YEARS AGO: Neanderthals emerge.
195,000 YEARS AGO: Homo sapiens coexist with other human species.
120,000 YEARS AGO:
