fireball after it has entered the atmosphere
Types
o stony iron, rarest meteors, only 2% or all meteors are stony-iron
o stone, most meteors are stone, formed the outer crust of a planet or asteroid/comet
o iron, 90%-95% iron, besides iron mostly nickel, formed the iron core of a planet or asteroid/comet, most craters on earth were caused by iron meteors, about 5% of meteors that fall to earth are iron meteors,
Meteor craters
o Meteor craters are caused when a meteor hits earth (duh)
o 2 types of craters simple and complex
o Collision with earth causes further fracturing of the meteor
o Atmosphere protects Earth from meteors by burning them to a size where they cannot do much damage besides initial impact
o Complex crater caused when Earth rebounds against the force of the meteor
Facts
o About 9 meteor showers per year
o Even a piece of dust that enters the atmosphere can be considered a meteor
o Most meteors are found in the south pole because they stand out against the natural landscape, many are also found in the desert for the same reason
-Meteors can act as a "boost" for radio signals sending them further
-Meteors can be knocked off their course by a nuclear weapon, this is called an X-ray slap
-You are more likely to win the lottery than be hit by a meteor, people are hit by meteors about every 189 years
Meteor showers
o More meteors than normal (normal being 1 per hour)
o Named after the closest consolation
o A common cause is when a comet breaks up and all of its pieces enter the atmosphere
Fireballs
o A meteor that is large enough to cast a shadow on earth
o Must also be generating its own light (on fire, hence the name fireball)
o Must be at least as bright as Venus
o Smaller fireballs travel fast enough to create a sonic boom
o Generally fireballs travel faster than normal meteors
Example
o Name: The Willamette Meteorite
o Found in: The Willamette valley, Oregon, 1906
o weight: 15.5 tones
o Type: iron meteor
o Mass: 3 meters * 1.9 meters * 1.9 meters
Example 2
o K-T Extinction is believed to have caused the Extinction of the dinosaurs and 80% of all species
o Only 13% of flora and fauna survived
o Meteor hit what is now the gulf of Mexico and created it
o In 2002 another crater was found in Boltysh, Ukraine from around the same time as the K-T meteor and it is now believed that the mass extinction was caused by multiple meteors
Example 3
o Allende meteorite
o One of the largest recorded fireballs
o Exploded about 547 KM south of El Paso Texas
o Caused no crater
o Caused a meteor shower
o Contains some of the oldest matter in our solar system
o When it exploded over Mexico it caused a meteor shower of all of its fragments and did not all hit earth in one spot