Collisions with the Earth
Let’s talk about the possibilities of collisions with the Earth.
Actually, our Earth is being hit all the time by cosmic dust and meteors. More often than not, these will fall into the atmosphere and burn up, producing a streak of light in the sky we call a “shooting star.” But sometimes the chunks are big enough so that part of the original chunk gets through the atmosphere. Anywhere between 5 – 300 metric tons of dust and meteors strike the Earth per day!
Meteors, though, are in a class not considered large enough to produce truly significant damage - so what are? Asteroids and comets. Asteroids are larger chunks of rock that are about 1 km in diameter. They exist mostly in the asteroid belt between the orbits of Mars and Jupiter. Comets are chucks of mostly ice, mixed with some rock, dust, and trapped gases and are about 3 km in diameter. They exist beyond Pluto. Through occasional collisions amongst themselves, some are sent into orbits around the Sun and providing that possibility of collision with Earth. Two famous collisions are the impact in the Yucatan peninsula 65 million years ago that wiped out the dinosaurs and the Tunguska event in Siberia in 1908.
But fear not! NASA tracks everything that gets within 3 million miles of Earth and there are protocols for objects that get too close!