Planetary Defense

In 2013, a 50-ft diameter meteor fell into the skies above Russia. Within a few hours, everyone in the world was watching the incredible videos of the streak of light it created while crashing to earth. Meteors hit the earth every single day, but most of them are only the size of a grain of sand, creating a brief “shooting star” in the sky as they burn up entirely in the atmosphere.
When larger rocks fall to the earth, the results can be devastating. In 2013, no one was killed by the falling meteor (although over a thousand people were injured by broken glass from the shock wave). But in 1908, a larger meteor hit Russia. It landed in a remote part of Siberia called Tunguska. If it had landed in a populated city, it could have killed thousands of people! Watch the video The Tunguska Event to learn about this incredible meteor impact.
Review 13.2 Asteroids and Planetary Defense to understand the potential threat posed by near-Earth asteroids (NEAs) and near-Earth objects (NEOs). Explore ongoing efforts, such as NASA’s Spaceguard Survey, to detect and monitor these objects, as well as research into planetary defense technologies.
Even the meteor that hit Tunguska was small compared to meteors we know have hit the earth in the past. Asteroids are enormous rocks in space that are the size of large cities. There are millions of them in our solar system, and astronomers are always finding more. There is some (legitimate) fear that one of these asteroids could impact the earth, potentially killing millions and changing our planet’s climate forever. Some astronomers (but not very many) are searching for potential killer asteroids in space. Watch the BBC clip Tracking Killer Asteroids to see how they search.
Use NASA’s Eyes on Asteroids simulation to explore the orbits of near-earth asteroids. Watch my brief Eyes on Asteroids Tutorial video for some quick tips on how to use the simulation.
Universe Sandbox is actually really good at simulating collisions in space. Watch the video Destroying the Earth where I launch asteroids of various sizes toward the earth to see what happens as a result.