Too
Close For Comfort?
|
|
|
|
|
Topic:
Type of Web
activity:
Materials /
Software needed:
Materials for construction
Audience:
Grade
Level:
Time
involved:
Created
on:
The Web Science Workshop lessons were created in cooperation with the Exploratorium Teacher Institute .
This site
developed and maintained by
Deborah
Hunt
and
Eric
Muller
.
3601 Lyon
St.
©2000 The Exploratorium |
|
Introduction Scientists around the world collect and share data about Near Earth Objects (NEO) , which are comets and asteroids that succumb to the force of earth's gravity and enter into the earth's orbit. Comets are huge balls of ice and dust, while asteroids are composed of stony and/or iron-based minerals. Every100 years or so, rocky or iron asteroids larger than about 50 meters would be expected to reach the Earth's surface and cause local disasters or produce tidal waves that might affect coastal communities. On an average of every few hundred thousand years or so, asteroids larger than a mile could cause global disasters portrayed in popular films such as Lucifer's Hammer . Web Lesson Scientists have developed a standard for estimating the chance of an NEO actually colliding with the earth. Specifically, all NEO's with a minimum orbit intersection distance (MOID) of 0.05 AU or less and an absolute V-magnitude (H) of 22.0 or less are considered potentially dangerous. 1) Visit an on-line skywatch site . Select a time period spanning at least one week. How many NEO's have been observed during this period? 2) Examine the data table of MOID values for selected asteroids. Would astronomers consider any of these dangerous? Explain why or why not. |
