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Approximately half a billion large asteroids orbit the Sun. Image: NASA
NASA has shared graphics estimating how many potentially hazardous asteroids could collide with Earth each year, as reported by Live Science on August 8th. On average, once a year, an asteroid measuring 4 meters will pass within a range of 2,600 km from Earth’s surface. A few thousand kilometers might seem quite substantial for an object of only a few meters in size; most of the asteroids mentioned in the media pass at a much greater distance. Astronomers consider anything that passes closer to Earth than the Moon (about 30,000 km) as a “close approach.”
Next, NASA examines larger asteroids with diameters of around one kilometer. Each such collision threat could jeopardize civilization, occurring once every 500,000 years. We could experience thousands of instances of asteroids flying by (closer than the Moon) during that time frame. An event like this is set to happen in 2029 when asteroid 153814 (2001 WN5) will pass Earth at a distance of 248,700 km.
Researchers estimate that about 95% of asteroids larger than one kilometer have been discovered, and they continually scan the sky to locate the remaining 5%. When a new asteroid is found, astronomers enhance observations to assess the risk to Earth.
Earth frequently experiences collisions with small asteroids, but it is rarely impacted by larger ones. In most cases, small asteroids disintegrate in Earth’s atmosphere, not even reaching the surface. They often create spectacular fireballs. The majority burn up within the atmosphere.
Currently, no object poses a risk of impacting Earth. Technology has advanced to a point where humanity can take action if faced with a high-risk asteroid collision. Recently, NASA’s DART mission involved deliberately impacting a spacecraft into an asteroid to alter its trajectory.
Asteroids are remnants of the solar system’s formation. About half a billion asteroids with diameters larger than 4 meters orbit the Sun, moving through the solar system at a speed of about 30 km/s, equivalent to Earth’s speed. Asteroids pose various threats to Earth. Approximately 65 million years ago, life on Earth was extinguished by an asteroid impact, leading to the mass extinction of dinosaurs. Even a 4-meter object moving at a speed of 60 km/h poses considerable danger. There are numerous smaller asteroids than the larger ones, and they cause significantly less damage.