On February 15, 2013, an asteroid traveling at 40,000 mph exploded approximately 15 miles over Chelyabinsk Oblast, Russia, causing about 1,500 injuries. The remaining part of the asteroid landed in a frozen lake.

WATCH A NEWS STORY ABOUT THE ASTEROID IMPACT

One of the fascinating aspects of near-Earth asteroids is that they rarely strike Earth. First, here is some introductory information about near-Earth asteroids:

Range in size from 1 meter to 32 kilometers

On average, an asteroid with a diameter of 4 meters strikes Earth once per year

Almost 10,000 near-Earth asteroids have been identified (these are asteroids which will cross Earth’s path at some point)

Asteroids with a diameter of 7 meters can cause damage comparable to that caused by the atomic bomb dropped on Hiroshima

Near-Earth asteroids are an interesting topic of study because expectations may not match reality. We may find that our fear about near-Earth asteroids is much greater than is reasonable based on how often these asteroids actually strike Earth. On the other hand, we may find that we actually are not worried enough about this danger and must do more to prepare.

TEST YOUR CRITICAL THINKING BY ANSWERING THREE DISCUSSION QUESTIONS IN THIS “THINK LIKE A…PHYSICIST” FORUM.

1) Discuss two concepts from the module to this idea of asteroids and asteroid impacts with the Earth.

2) How much risk is involved compared to death from other accidents such as plane crashes? Are the consequences of the event happening the same for a plane crash or an asteroid hitting the Earth?

3) Does likelihood or the severity of consequences change the type of evidence you would need to believe a claim? For example, if I said that we need to spend a billion dollars on an asteroid defense system because we will probably need it in the next 10 years. What kind of evidence would you require? Would it be the same if I said that we need to spend a billion dollars on better air traffic controllers