Incoming meteoroids enter the earth’s atmosphere at 11 km/sec to 72 km/sec. The kinetic energy of an object of mass m traveling at a speed v is = (½) mv 2, provided v is much less than the speed of light. If the meteoroid is of sufficient size to keep it’s hyper-velocity >12 km/sec through the atmosphere becoming an impactor, it will impact the ground and explode. The meteor will arch into a more vertical trajectory, slow to terminal velocity of about 0.1 km/sec and fall as a meteorite. Light emission from incandescence and ion recombination ceases. If a meteoroid’s size, composition, speed and entry angle allow it to survive the “meteor” phase of entry, it will slow to about 4 km/sec and enter “dark flight” at 20 km to 15 km above earth. The left-over debris is called meteoric dust or just meteor dust. In a couple of seconds most meteors are have been consumed. Energy goes into melting and vaporizing stone and metal. This plasma becomes visible at between about 120 km and 75 km above the earth. Ram pressure between the air and the object create a very high temperature plasma at the front of the meteor. Instead, they drift downwards through the atmosphere.Meteorite Self Test 73rd Annual Meteoritical Society Meeting (2010) 1. There are more micrometeorites that hit Earth than any other type, as there are more in space and also they are too small to be burnt up in the Earth’s atmosphere. The most famous crater is Barringer Crater, shown on the right in Arizona, USA.Ī micrometeorite is a micrometre-sized meteorite. There are few large craters on Earth’s surface as they are usually covered over by geological processes such as the weather, earthquakes etc. Typically they are made of stone or iron, and their exteriors are often smooth due to the crust melting through the atmosphere.Ī meteorite collision is thought to have caused mass extinctions of life on Earth in the past. Most are not observed and fall into the oceans, deserts or less populated areas. If a meteor survives the entry into Earth's atmosphere it will land as a meteorite.Ībout 10% of meteors survive to hit Earth’s surface and land as meteorites, having not been burnt up by Earth’s atmosphere. Very bright meteorites are large and can even be seen in the day-time sky as a fireball. They are popularly known as SHOOTING STARS.Įarth's atmosphere burns up the meteoroid because the high speed of the object produces immense friction and typically the object is vaporised. They can be observed at night time when they can be seen as a streak of light across the sky. MeteorĪ meteor is a meteoroid that enters Earth's atmosphere. Impacts on Mars has thrown up Martian debris into space and have landed on earth. There are also those that have their origins from other planets and larger bodies. Asteroidal meteoroids which are particles fallen off or chipped off asteroids Cometary meteoroids which are small particles shed by comets Meteoroids, Meteorites & Micrometeorites 11.1 - Be able to use data about the names and relative locations of bodies in the Solar System, including:Ĭ) Small Solar System Objects (SSSOs): asteroids, meteoroidsġ1.10 - Understand the origin and structure of meteoroids and meteorites MeteoroidĪ meteoroid is an object in space, possibly similar to an asteroid that will eventually become a meteor.
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