Scientists believe the Big Bang occurred around 12-14 billion years ago, forming galaxies, stars, and planets. A supernova 7 billion years ago from a giant star produced a solar nebula of dust and gas that collapsed under gravity to form our sun and planets. Earth began as a molten ball surrounded by an atmosphere of hydrogen and helium 4.6 billion years ago. Early volcanoes emitted gases that formed Earth's atmosphere, with oxygen increasing over time to allow life to evolve on land.

1. Earth's Place In Space

2. Earth's Place In Space Origin Of The Universe Big Bang Theory

3. How our solar system formed Earth's Early Atmosphere

4. Evolution

5. Origin Of The Universe Big Bang Theory Scientists believe that there was a giant explosion around 12-14 billion years ago.

6. Atomic particles from the explosion later formed galaxies, stars, and planets.

7. Supernova 7 Billion years ago, a supernova occurred from one of the first generations of giant stars exploding.

8. A supernova occurs at the end of a stars life, releasing huge amounts of energy.

9. Solar Nebula The energy released from the first generation of stars exploding, produced a solar nebula.

10. A solar nebula is thought to be a spinning cloud of dust and gas.

11. Solar Nebula Gravity caused the spinning could of dust and gas to collapse and condense forming our Sun in the center.