Unit 14
Meteor Explodes Over Russia
[based on actual events]
Getting Started
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An explosive event in February of 2013 shows us the dangers that can happen when space debris strikes our atmosphere. A meteor 20 meters wide travelling at 68,400 km per hour exploded over central Russia near Chelyabinsk. The blast blew out windows damaging more than 7,000 buildings and sent more than 1400 people to the hospital with cuts and scrapes.

The light from the blast was 30 times brighter than then sun causing skin burns similar to sunburn. The shock wave was so strong that many early morning pedestrians were thrown to the ground.

The power from the blast was 30 times stronger than an atomic bomb. Fortunately, the blast was 40 km high above earth's surface which allowed the earth's atmosphere to absorb most ot the shock. If the blast had occurred closer to the ground or if the giant rock was just several meters larger, the destruction would have been enormous—levelling buildings and killing thousands of people.

This blast is the biggest known meteor explosion since the 1908 Tunguska meteor blast which flattened 80 million trees in a remote area of Siberia. The Tunguska blast levelled an area more than twice the size of the New York city metropolitan area.

These two events, which have taken place in just over a single person's lifespan, show us not only the danger but the likelihood of larger objects striking the earth and causing complete destruction of cities or even complete devastation to the whole planet.

America's national space agency, NASA, takes these threats seriously and has established a program for finding and tracking near earth objects (NEOs). More than 13,500 NEOs of all sizes have been discovered to date. About 1,500 new NEOs are detected each year.

NASA has discovered 90 percent of NEOs larger than 1 km and are now focusing on finding objects that are slightly bigger than a football field -- 140 meters or larger. NASA's goal is to find 90 percent of this class of NEOs by the end of 2020 and has found 25 percent of these mid-sized objects to date.

NASA also has long-term planetary defense goals which include finding ways to deflect or redirect objects that are on an impact course with Earth.

Comprehension Questions
  1. How large and how fast was the Chelyabinsk meteor?
  2. How high above the ground was the meteor when it exploded?
  3. What kinds of damage did the blast cause? Kinds of injuries?
  4. What absorbed most of the shock from the explosion?
  5. What would happen if the the meteor exploded closer to the ground or was a larger size?
  6. How many trees were levelled by the Tunguska blast?
  7. How big was the area that was flattened by the Tunguska blast?
  8. What kind of program has NASA established?
  9. How many NEOs have been discovered so far?
  10. What does NASA's long-term planetary defense goals include?
Discussion
  1. What's the difference between a meteor, an asteroid, and a comet? (Google It)
  2. NASA says an asteroid the size of a football field may be heading toward your city. It will be their in two days. What would you do?