Why an asteroid?
On February 15, 2013, while the world watched and waited for Asteroid 2012DA14 to approach Earth on a close flyby, a second and completely unrelated asteroid burst through our atmosphere and disintegrated in the skies over Chelyabinsk, Russia. Although meteors are not uncommon events (in fact, an average of 100 tons of meteoroids falls on Earth daily), the surprise blast occurred over a populated area. Locals captured stunning images of the fireball breaking up over the cityscape—and the damage caused by from the shockwave that followed—and shared them extensively on social media outlets. Suddenly, understanding asteroids—especially detecting and predicting their behaviour—became headline news.
Asteroids appear to be the unruly, rebellious objects of our Solar System, with seemingly bizarre orbits that occasionally bring them uncomfortably close to Earth—and, like the Chelyabinsk meteor, sometimes make them unwelcomed visitors. In addition to efforts to detect and track asteroids, scientists are very interested in studying them to learn more about the evolution of our Solar System, how the planets formed, and even how asteroids may have contributed to the origins of life on Earth.
Asteroids are essentially remnants of the primitive building blocks that created the terrestrial planets in our solar system. Scientists believe that asteroids have not changed very much since the time they were formed, making them cosmic time capsules that can reveal how planets like our own world formed. In addition, asteroids are thought to contain organic molecules like amino acids—the basis for proteins and DNA—leading to speculation that a meteorite from an asteroid could have seeded the early Earth with the building blocks of life.
What's the difference between an asteroid, a comet, a meteor and a meteorite?
Asteroids are composed mainly of rock and metals, while comets are made of ice, dust and small rocks. An object becomes a meteor if it enters Earth's atmosphere. Since meteors leave visible streaks across the sky, they are often known as shooting stars. The term "meteorite" refers to solid debris that survives entry and impact with the ground.
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