• What are the odds of an asteroid or comet hitting the Earth? • Has this happened in Earth’s past? • What would happen to Earth’s civilization in the event of a collision? • What can be done to protect Earth? Artist’s impression of an asteroid impact with Earth (ESA)
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What are the odds of an asteroid or comet hitting the Earth? Has this happened in Earth’s past?
What are the odds of an asteroid or comet hitting the Earth? Has this happened in Earth’s past? What would happen to Earth’s civilization in the event of a collision? What can be done to protect Earth?. Artist’s impression of an asteroid impact with Earth (ESA) . - PowerPoint PPT Presentation
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• What are the odds of an asteroid or comet hitting the Earth?
• Has this happened in Earth’s past?
• What would happen to Earth’s civilization in the event of a collision?
• What can be done to protect Earth?
Artist’s impression of an asteroidimpact with Earth (ESA)
• During a period between 4.0 and 3.8 billion years ago, called the Late Heavy Bombardment, the newly formed Earth was being constantly bombarded by asteroids, comets, and debris left over from the formation of the solar system
• Since then the number of asteroids that have hit the Earth has dramatically decreased
• Probably the most famous object that hit the Earth is the one that created the Chicxulub crater and caused the extinction of the dinosaurs 65 million years ago
• Closer to home, Meteor Crater in Arizona was created 50,000 years ago by a large object slamming into the Earth
• Sentry, a computer system developed by NASA’s Jet Propulsion Labs, calculates the odds of Near-Earth Objects (NEO’s) coming close to or hitting the Earth within the next 100 years
• It figures the object’s coordinates, distance, velocity, and gravitational influences to calculate its trajectory
• This sometimes requires months or years for the calculations to be accurate
• Dust from the impact will block the sunlight from reaching Earth and cause nuclear winter. Plant photosynthesis will stop and the food-chain would collapse
• After the planetary cooling, a greenhouse effect will increase the Earth’s temperature because of the increase of carbon dioxide in the atmosphere
• If an asteroid is predicted to hit Earth there are some proposals to alter the orbit of an asteroid in a controlled manner:
• Give the asteroid a “shove” to move it out of Earth’s way, but there is a risk of breaking the asteroid into many pieces which will increase the threat
• Use gravitational effects by putting a spacecraft alongside and using gravitational attraction between the two to pull the asteroid off course