Hundreds of people can walk by your front door every day. The only time you may notice someone, however, is when they knock.
Last week, the universe knocked on Earth’s door.
Thousands of asteroids and meteoroids streak pass planet Earth every year. Some of them enter Earth’s atmosphere where most of them simply burn up—those are called meteors. Any that land on Earth are called meteorites. (See NASA’s chart below for more definitions.)
When a meteorite landed in the city of Chelyabinsk, Russia last Friday, the world took notice. That’s because it was a particularly large meteorite; one chunk was about the size of a van.
Where did it come from?
The meteorite came from the asteroid belt between Mars and Jupiter, according to a report from NASA on the CBC news website.
The meteorite was made up mostly of rock. It was going very fast—at least 54,000 kilometres an hour (by comparison, the speed of sound is 1,236 kilometres per hour).
The meteor broke apart over Russia with a huge boom (known as a sonic boom) that shook buildings and broke windows.
It is estimated that the event did more than $33-million worth of damage and many people were injured, mostly by broken glass from windows. Forty-eight people (in a city of one million) went to hospital; no one was reported killed.
The sonic boom happened because the fast-moving meteor “punched a hole in the air,” explained Bob McDonald, the CBC’s science correspondent in a recent interview with CBC news.
Why it exploded
Because it was travelling so fast, it heated up the air in front of it to thousands of degrees while the back side of it was still cold—as cold as space, where it came from. It slowed down so quickly that it got squeezed, which caused it to explode outwards, high in the sky, McDonald explained.**
Scientists track meteors all the time. A Canadian space telescope called NEOSSat (the Near-Earth Object Surveillance Satellite) will be sent into space later this year to locate and keep track of meteors. After that, any large meteors will eventually be able to be pushed out of the way so they don’t come into contact with Earth.
McDonald explained that the larger a meteor is, the easier it is for scientists to detect and track it.
In Chelyabinsk, more than 24,000 people are working to help residents by covering their windows, giving them warm clothing and food, and helping them clean up.
*The sound barrier and the concept of the “speed of sound” are advanced—and fascinating—scientific topics. If you’re interested in science, it’s worth looking into. (See “related links,” below.)
NASA explains the “sound barrier” in kid-friendly language.
NASA explains the “speed of sound.”
Wikipedia explains “the speed of sound.”
**Here is a link to the CBC interview with Bob McDonald, explaining the phenomenon.
(Note: The CBC news website is not specifically a kid-friendly site so kids must have an adult’s supervision. Also, there is a 15-second ad ahead of the clip. The clip is 3:52.)
By Jonathan Tilly
Size is relative. When an object the size of a bus is orbiting around the sun, it’s considered very small–almost too small to even track from Earth. However, when an object the size of a bus hits the Earth, it’s considered big. If it’s the same object, and the same size, how can it be both “small” and “big”?
Reading Prompt: Comprehension Strategies
Here are some definitions from NASA, explaining the differences between asteroids, meteroids and meteors. How does this compare to your understanding of these terms. Do these definitions change your understanding of today’s article? How so?
Asteroid A relatively small, inactive, rocky body orbiting the Sun.
Comet A relatively small, at times active, object whose ices can vaporize in sunlight forming an atmosphere (coma) of dust and gas and, sometimes, a tail of dust and/or gas.
Meteoroid A small particle from a comet or asteroid orbiting the Sun.
Meteor The light phenomena which results when a meteoroid enters the Earth’s atmosphere and vaporizes; a shooting star.
Meteorite A meteoroid that survives its passage through the Earth’s atmosphere and lands upon the Earth’s surface.
Primary & Junior
Identify a variety of reading comprehension strategies and use them appropriately before, during, and after reading to understand texts (OME, Reading: 1.3).
Identify a variety of reading comprehension strategies and use them appropriately before, during, and after reading to understand increasingly complex texts (OME, Reading: 1.3).
Grammar Feature: Scientific Terms
Using the correct terms when writing about a scientific topic is really important. It prevents confusion and adds to the reader’s understanding. To prove this point, take a look at this chart: http://neo.jpl.nasa.gov/faq/#diff. Now take another look at today’s article and the headline. Each time the object was described, it was called a “meteor” or a “meteorite,” depending on where it was located. Did the reporter get every mention correct? Why, or why not? In other news reports you may have read or heard about the event, was the object described accurately in this way?
With an adult, search “Chelyabinsk” on the web and pay attention to whether or not the correct scientific terms are used.