this picture shows the "meteor crater" in arizona which is 180 meters deep and 1.2 km in diameter with an eroded rim standing 30-60 m high. this crater is believed to have been made 50,000 years ago by a 46-meter wide meteorite composed of nickel-iron rock.
billions of objects enter earth's atmosphere everyday. they are mostly small things that burn up as they pass thru the atmosphere (we call these meteors). the objects that reach all the way to the earth's surface are called meteorites.
this video (7 min) shows a cool japanese-produced simulation of what could happen if a gigantic impact occured on earth....
i'm not intending to scare everyone by showing the fatal effects of that impact. in reality, an object that huge only hits the earth once every 100 million years or more. thats a very long time! the chart shows the frequency with which meteorites of different sizes are believed to reach earth.... and thats not even counting all the cosmic garbage!!
according to this chart, an impact like the one that made the meteor crater above should happen about every 5,000 years or so... and that one was 50,000 years ago! looks like we might be over due! good thing groups like the near-earth objects (NEOs) program and the Lincoln Near Earth Asteroid Research (LINEAR) program are constantly monitoring the skies in search of potentially approaching objects!!
No comments:
Post a Comment