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| Question | Answer |
| P2g - Threats to Earth | . |
| Asteroids | Asteroids are mini-planets or planetoids orbiting the sun: -Most are found in an ‘asteroid belt’ in orbit around the Sun between Mars and Jupiter. -they are large rocks that were left over from the formation of the Solar System Asteroids can crash into each other. When they do, they can break apart and change orbit. |
| Asteroids (continue)... | The orbits of some asteroids cross the Earth’s orbit. At various times during the Earth’s history, asteroids have hit it. A tremendous amount of energy was released, throwing up billions of tonnes of dust and hot rocks. Together with smoke from widespread fires, this blocked heat and light from the Sun. It changed the Earth’s climate, making it very cold. |
| Comets | Comets are balls of ice and dust that orbit the Sun. Their orbits are different to those of planets: they are highly elliptical (an oval). A comet’s orbit takes it very close to the Sun, then far away, beyond the planets. The time to complete an orbit varies - some comets take a few years, others millions of years. The speed of a comet increases as it approaches the Sun. This is because the strength of gravity increases. |
| NEOs | An NEO is a Near Earth Object. If an NEO were to be detected on a collision course with Earth, it may be possible to deflect the NEO using explosions. If enough force could be applied early enough, the NEO could be nudged into a different trajectory that missed the Earth. |
| The asteroid belt | Most asteroids lie in the asteroid belt located between Mars and Jupiter. Jupiter is a very large planet with a very large gravitational field strength. Its gravity stops rocks from coming together to form a planet. Instead, they orbit the Sun as asteroids. |