Meteors, meteorites & asteroids

[bolloman]

Hey all,<br /><br />I'm brand new here and I've really enjoyed reading some of the posts in various discussions here. It's really cool to find this place. I have a couple questions that have been burning in my brain for the last month or so and I haven't been able to find an answer in my searches online.<br /><br />I've read that most shooting stars that we see are a meteorite the size of a grain or sand or a pea.<br /><br />I get the idea that fireballs must be the size of a basketball.<br /><br />I read an article about a meteor that was estimated at 10 meters that burned up over the south pole leaving a great cloud of dust particles behind...but it apparently burned up and never impacted.<br /><br />I read that the crater in Arizona was created by a meteor the size of a house.<br /><br />What size does a meteor need to be in order to actually impact the earth before burning up? How much does angle of entry have to do with it?<br /><br />Also, at what point is an object considered a meteorite, meteor or asteroid? and...when an asteroid is said to be 10 or 300 meters, is that at the longest point or the narrowest diameter?

 

[astroboy3k]

Question 1: <font color="yellow">What size does a meteor need to be in order to actually impact the earth before burning up?</font><br />Answer: Earth's atmosphere is ineffective in preventing ground impact damage for stony meteorites greater than 200 meters (about 650 feet) in diameter. For iron meteorites that impact at greater than 20 km/sec (12.5 mi/sec), the critical diameter is about 40-60 meters (130-200 feet). Stony bodies greater than 60 meters and less than 200 meters can cause significant airburst damage<br />Question 2: <font color="yellow">How much does angle of entry have to do with it?</font><br />Answer: I do not know.<br />Question 3: <font color="yellow">Also, at what point is an object considered a meteorite, meteor or asteroid?</font><br />Answer: Definitions<br />meteorite - piece of comet or asteroid debris from space that does not completely disintegrate in Earth's atmosphere<br />meteor - a streak of light in the night sky caused by a speck of comet or asteroidal dust burning up in Earth's atmosphere<br />asteroid - a rocky body orbiting the sun, most of them are found on the asteroid belt between Mars and Jupiter.<br />comet - a ball of frozen rock and ice orbiting the sun <br /><br />Question 4: <font color="yellow">and...when an asteroid is said to be 10 or 300 meters, is that at the longest point or the narrowest diameter?</font><br />Answer: Ceres is another asteroid with a diameter of 933 km. Others like 2 Pallas, 4 Vesta, and 10 Hygiea have between 400 - 525 km in diameter.<br />