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4589 BCE
Planetary Accretion
About 4.6, 4.5 billion years ago
The solar system began as a huge cloud of stardust including dust, rocks and gas. About 4.6 million years ago, a near by star exploded and its impact increased the speed of the spinning cloud of stardust. Because of this, most mass concentrated in the middle of the cloud, which formed the sun. The smaller mass rotating around the sun formed planets, including the Earth. -
4510 BCE
Core Formation
About 4.5 billion years ago
Different materials in the cloud of stardust collided and formed planets. The collisions caused the Earth to heat up, rock and metal melted, and the molten materials separated into different layers. The lighter materials rose to the surface, and gravity pulled the denser materials to the center. Therefore, Earth's core is mostly made out of iron. -
4470 BCE
Formation of the Moon
About 4.5 billion years ago
70 million years after the Earth was formed, there was an asteroid the size of Mars smashed into the Earth. Material from both the Earth and the asteroid flew out into orbit. Over time, these materials came together and formed moon. -
4110 BCE
Planetary Cooling
About 4.4 billion years ago
At the beginning, Earth was molten. Over time, the planet cooled and formed a solid crust. As Earth continued to cool down, volcanoes released gases, and the released gas formed atmosphere. As the atmosphere became denser, clouds formed and rain fell. Water from rain formed the ocean. -
3800 BCE
End of Heavy Bombardment
About 4 billion years ago
The planets and moons in our solar system are all covered by impact craters, and this was caused by collisions in the solar system. The asteroids and comets that hit Earth actually gave extra material for life.