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Asteroids - NEO’s – Near Earth Objects

Not all asteroids are in a circular orbits about the Sun or at the Lagrange points. There are some asteroids that are in elliptical orbits that can bring these asteroids close to Earth. These asteroids are called Near Earth Objects, or NEO's. More information can be found on the Near Earth Object Fact Sheet.

NEO's have struck Earth in the past. Examples are:

  • The Tunguska Event in 1908
  • The Barringer Meteorite Crater - impact about 50,000 years ago
  • Extinction of the dinosaurs - 10 km meteorite impact about 65 million years ago

This image of the Barriner Meteorite Crater gives a bit of a sobering warning of the potential hazards of NEO's:

This crater is 167 meters deep and 1.22 kilometers in diameter! This impact was no where near the significance of the impact that caused the extinction of the dinosaurs.

The extinction of the dinosaurs is believed to have occurred at the K-T boundary (K = Cretaceous Period, T = Tertiary Period). This boundary corresponds to 65 million years ago. The impact crater is believed to be in Mexico's Yucatan Peninsula (lower Gulf of Mexico) called Chicxulub. This impact crater is believed to be about 10 km in diameter with the energy of the impact roughly equal to 100,000,000 megatons of TNT (6 million times the energy of the Mount St, Helen's eruption in 1980). Here is a diagram of the Chicxulub crater:

Notice that the crater is now underwater.

Smaller meteors have also impacted Earth, even in the present time. Meteors that survive passage through the atmosphere and impact are called meteorites while the space debris that burns up in the atmosphere are called meteors. In space, these objects are called asteroids. There are three major types of meteorites:

  • Stony meteorites - combination of equal parts of rock and iron

  • Iron meteorites - contain little of no stone and about 10 to 20% nickel

  • Carbonaceous chondrites - containing carbon compounds and may also contain water bound up in minerals (as a result of heating)

While these smaller meteorites are of little concern, there are programs designed to keep a close watch on the NEO's.

Amateurs can also participate in NEO studies. While the equipment amateurs have access to will be unable to discover new objects, the tracking of existing objects is possible. The Committee on Science, U.S. House of Representatives hearing on The Threat of Near-Earth Asteroids acknowledges the amateurs contribution to this search.

Amateurs can do real science! While my area of interest is exoplanet detection, I have also entertained the idea of owning a dedicated telescope to assist in the tracking of NEO's.

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