4.6 billion years ago (or 46 million centuries or 4.6 million millennia) Earth formed, when supernovae stars that had reached the end of their lives, exploded.
These stars produced all chemical elements we know, from hydrogen and oxygen to radioactive elements such as uranium and plutonium.
Over time, gravity began to act and condense the clouds of gas and dust. A star appeared in the center: our Sun, surrounded by all the planets.
How do we know the age of the Earth? In 1953, a young geologist by the name of Clair Patterson decided that since it was not easy to find the oldest rocks on the planet, the best idea would be to measure the age of a meteorite. Meteorites formed at the same time as the entire solar system. And so he did. He estimated the age of a meteorite that had fallen in Arizona 50,000 years ago and reached the figure of 4.55 billion years.
Today the discussion is in the second or third decimal of that figure.