A size that counts.

[zarnic]

<p>I recently read an article about the Tunguska explosion and nearby&nbsp;Lake Cheko. The article used the word 'meteor-size' when describing what might have been the cause of this event.&nbsp; Fine, but ... what the heck is meteor-size, the article doesn't explain? If the size of a meteor has a lower limit then does it also have an upper limit too?&nbsp; I have even seen the phrase 'planetary-size' and when comparing Mercury to Jupiter one has to wonder how big that is, too.</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Wisdom doesn't automatically come with old age. Nothing does - except wrinkles.</em> A. Van Buren, 1978<br />* <em>An unbreakable toy is useful for breaking other toys.</em>  -- according to Van Roy</p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I recently read an article about the Tunguska explosion and nearby&nbsp;Lake Cheko. The article used the word 'meteor-size' when describing what might have been the cause of this event.&nbsp; Fine, but ... what the heck is meteor-size, the article doesn't explain? If the size of a meteor has a lower limit then does it also have an upper limit too?&nbsp; I have even seen the phrase 'planetary-size' and when comparing Mercury to Jupiter one has to wonder how big that is, too. <br />Posted by zarnic</DIV><br /><br />In a sense it's a meaningless term, since there is no official dividing line metween meteoroids, asteroids, and HOLY COW WHAT IS THAT???.</p><p>Meteoroids are the particles that create meteors. They range in size from much smaller than a millimeter to maybe meter sized. There's no official diference between that and a "bolide" Meteor brighter than Venus, sort of.</p><p>An asteroid is bigger. How much? It is not defined. Is a 5 meteor object&nbsp; meteoroid or an asteroid? Who knows, It's </p><p>an "oid".</p><p>Now that we can track objects of this size, the definition might change. Something like Tunguska would seem to be in the asteroid or comet category.</p><p>A meteoroid is a tiny asteroid </p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[zarnic]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In a sense it's a meaningless term, ....</DIV></p><p>'A meaningless term', yet it is used anyway ... ummmm. Thank you for educating me.</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Wisdom doesn't automatically come with old age. Nothing does - except wrinkles.</em> A. Van Buren, 1978<br />* <em>An unbreakable toy is useful for breaking other toys.</em>  -- according to Van Roy</p> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>'A meaningless term', yet it is used anyway ... ummmm. Thank you for educating me.&nbsp;&nbsp;&nbsp; <br />Posted by zarnic</DIV><br /><br />As a meteoricist, I often come across this. Unlike Planet or Star which have official definitions, meteoroid and asteroid have no such "official" definitions. I find it rather frustrating, but it is a valid question, which is difficult to answer. Where do you draw the line between a meteoroid and an asteroid? <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[zarnic]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>.... Where do you draw the line between a meteoroid and an asteroid? <br />Posted by MeteorWayne</DIV></p><p>A querey of an online dictionary gave this definition for a meteroid: <em>'any of the small bodies, often remnants of comets, traveling through space'</em>.&nbsp; Using the word <em>'any' </em>allows a lot of room for interpretation however there is a distinct difference between asteroid and comet.&nbsp; There are others who visit this forum who are more capable to speak of this and I will turn the thread over to them. TY.</p><p><br /><br />&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Wisdom doesn't automatically come with old age. Nothing does - except wrinkles.</em> A. Van Buren, 1978<br />* <em>An unbreakable toy is useful for breaking other toys.</em>  -- according to Van Roy</p> </div>

 

[bearack]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>A querey of an online dictionary gave this definition for a meteroid: 'any of the small bodies, often remnants of comets, traveling through space'.&nbsp; Using the word 'any' allows a lot of room for interpretation however there is a distinct difference between asteroid and comet.&nbsp; There are others who visit this forum who are more capable to speak of this and I will turn the thread over to them. TY.&nbsp; <br />Posted by zarnic</DIV><br /><br />Well, your slam on Wayne's abilities is noted.&nbsp; You just dissed one of the most knowledgeable people in this forum on this subject.&nbsp; Way to go!</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><br /><img id="06322a8d-f18d-4ab1-8ea7-150275a4cb53" src="http://sitelife.space.com/ver1.0/Content/images/store/6/14/06322a8d-f18d-4ab1-8ea7-150275a4cb53.Large.jpg" alt="blog post photo" /></p> </div>

 

[zarnic]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Well, your slam on Wayne's abilities is noted.&nbsp; You just dissed one of the most knowledgeable people in this forum on this subject.&nbsp; Way to go!&nbsp;&nbsp; <br />Posted by bearack</DIV><br />Huh? No slam intended and my apologies to MW if taken that way. Now ...&nbsp;on with the show!</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Wisdom doesn't automatically come with old age. Nothing does - except wrinkles.</em> A. Van Buren, 1978<br />* <em>An unbreakable toy is useful for breaking other toys.</em>  -- according to Van Roy</p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Huh? No slam intended and my apologies to MW if taken that way. Now ...&nbsp;on with the show!&nbsp; <br />Posted by zarnic</DIV><br /><br />LOL, I didn't take it that way. I was demonstrating there is no real definition that gives a dividing line. In fact today the line gets fuzzier every day. We are discoveing "asteroids" 5- 10 meters across making close approaches to earth. If they hit the atmosphere, they probably wouldn't make it to the ground intact, so were they really meteoroids then?</p><p>Sometimes squeezing reality into categories leaves a lot of stuff hanging out of the boxes, witness the Pluto debate from 2 years ago. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-foot-in-mouth.gif" border="0" alt="Foot in mouth" title="Foot in mouth" /></p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

<p>Just as an example, on June 1, 3 "asteroids" passed close to the earth</p><p>2008 LD, 4.3-9.6 meter passed 1.1 Lunar Distances away</p><p>2008 KO, 35-78 meter passed 4.4 LD away</p><p>2008 LH2 38-84 m passed 8.4 LD away</p><p>On June 3, 2008 KT (funny coincidence) 6-14m passed 3.3 LD away.</p><p>The middle two, I'd call asteroids, but the 1st and 4th..????</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[zarnic]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Just as an example, on June 1, 3 "asteroids" passed close to the earth2008 LD, 4.3-9.6 meter passed 1.1 Lunar Distances away2008 KO, 35-78 meter passed 4.4 LD away2008 LH2 38-84 m passed 8.4 LD awayOn June 3, 2008 KT (funny coincidence) 6-14m passed 3.3 LD away.The middle two, I'd call asteroids, but the 1st and 4th..???? <br />Posted by MeteorWayne</DIV></p><p>Glad you didn't take offense, MW.&nbsp; Incidently, for those interested, NASA has a web site for Near Earth Objects plus a chart that has the&nbsp;diameter in km.&nbsp; 2008 LD has a diameter shown as&nbsp;.005 km while 2008 KT is at .008 km.&nbsp; A km-size object seems small and is better stated in those meter readings you give. Thanks.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>Wisdom doesn't automatically come with old age. Nothing does - except wrinkles.</em> A. Van Buren, 1978<br />* <em>An unbreakable toy is useful for breaking other toys.</em>  -- according to Van Roy</p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Glad you didn't take offense, MW.&nbsp; Incidently, for those interested, NASA has a web site for Near Earth Objects plus a chart that has the&nbsp;diameter in km.&nbsp; 2008 LD has a diameter shown as&nbsp;.005 km while 2008 KT is at .008 km.&nbsp; A km-size object seems small and is better stated in those meter readings you give. Thanks.&nbsp; <br />Posted by zarnic</DIV><br /><br />Here's a chart of close approaches giving diameter in meters that I got my data from. It's really impressive how many small "oids" we are discovering lately. All 2008 ones listed were discovered this year. Those with first letter K were discovered from May 16-31, the L's are June 1-15.</p><p>http://neo.jpl.nasa.gov/ca/</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[neilsox]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I recently read an article about the Tunguska explosion and nearby&nbsp;Lake Cheko. The article used the word 'meteor-size' when describing what might have been the cause of this event.&nbsp; Fine, but ... what the heck is meteor-size, the article doesn't explain? If the size of a meteor has a lower limit then does it also have an upper limit too?&nbsp; I have even seen the phrase 'planetary-size' and when comparing Mercury to Jupiter one has to wonder how big that is, too.&nbsp;&nbsp; <br />Posted by zarnic</DIV><br />If I recall correctly, someone else said the Tangduska&nbsp;explosion was about 100 meters in diameter. Others suggested somewhat larger. We really don't have much evidence, The speed, angle, composition and the amount of adhesion and cohesion all make a difference in the results. 100 meter asteroids typically are not spherical, so it is more precice to mention major axis and semi major axis. i agree numbers are much more helpful, even if they are mostly guess work. I would think a meteor could have large dimention anywhere from one metor to one million meters = about the size of the largest asteroid, which would surely destroy all life on Earth, unless it skimmed the outer atmosphere and kept going.&nbsp;&nbsp; Neil

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If I recall correctly, someone else said the Tangduska&nbsp;explosion was about 100 meters in diameter. Others suggested somewhat larger. We really don't have much evidence, The speed, angle, composition and the amount of adhesion and cohesion all make a difference in the results. 100 meter asteroids typically are not spherical, so it is more precice to mention major axis and semi major axis. i agree numbers are much more helpful, even if they are mostly guess work. I would think a meteor could have large dimention anywhere from one metor to one million meters = about the size of the largest asteroid, which would surely destroy all life on Earth, unless it skimmed the outer atmosphere and kept going.&nbsp;&nbsp; Neil <br />Posted by neilsox</DIV><br /><br />I believe the lataest data suggest it was <strong>much</strong> smaller than that. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>