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Scientists believe that about 5 billion years ago, a massive explosion sent gas and dust swirling into space.
It might have been caused by a supernova, or exploding star. Gravity made the dust clump together. Over the next 500 million years, the Sun formed. Then came the eight planets, five dwarf planets, and 181 moons. And let’s not forget the countless asteroids and comets that make up the solar system.
Earth’s birthday took place about 4.5 billion years ago. Our planet’s history is so long that scientists use the geologic timescale to measure it. Modern humans have been around for only the last 1.6 million years. Here’s a brief history of the world.
