Shooting stars changing direction at sharp angles?!?

[mrtuft]

Thanks for the help what your describing is very much along the sames lines as myself, in work at the min so might draw some directional paths when I get a minute! Glad someone else has seen something alog the same lines!!

 

[mrtuft]

nope.

 

[disownedsky]

<p>That does help. N. Ireland is about 54 deg N latitude, and the object being overhead makes a meteor very unlikely and space debris less likely, since for the debris to be illuminated it has to be in the atmosphere.<br /><p>Also, knowing it was overhead means that if it was space debris, then the inclination of the orbit had to be at least 54 degrees. Can you tell the compass direction it was moving in when you first saw it?</p></p>

 

[MeteorWayne]

Being at 54 North has nothing to do with meteors being seen overhead. Meteors can be seen moving in any direction in any part of the sky anywhere in the world.<br />Only shower meteors have a directional constraint, but even these can be seen in any part of the sky, moving left, right, up or down depending on where the radiant is at the time.<br /><br />Space debris is possible almost anywhere, since we do have polar orbiting satellites. There are more aobjects in near equatorial orbits, however. <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>

 

[disownedsky]

<p>I was unclear . The main thing knowing the latitude COMBINED with knowing that the object is overhead does for us is filter out possible reentering satellites with inclinations much less than 54. There are many satellites with inclinations greater than that, so it's only some help.<br /><p>Simply knowing that the object was at a low zenith angle means that if you were looking right down its relative velocity vector, a meteor would have punched through the atmosphere above you pretty quickly. The stopping behavior observed would be almost impossible. At a high zenith angle, you could be looking through about 10 times as much atmosphere, and the observed lateral motion could appear to briefly stop.</p><br /><p>The white color could be an important clue, but I wish it had been brighter. For a blackbody radiator to look white, it's got to be very hot, however dim objects may look whiter than they are. Nevertheless, I posit that a piece of space debris drifting down through the lower atmosphere at low speeds wouldn't glow white, but would be red or even invisible.</p></p>

 

[yevaud]

<i>Nevertheless, I posit that a piece of space debris drifting down through the lower atmosphere at low speeds wouldn't glow white, but would be red or even invisible.</i><br /><br />That would be a function of it's mass, angle of reentry, and composition (localized density) of the atmosphere it has descended through. It is impossible to state what you did without knowing these things accurately. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[MeteorWayne]

OK, the way I interpreted your post was that a meteor overhead would also be unlikely.<br />Sorry if I read it wrong.<br /><br />You are correct, an object (meteoroid or other) appearing overhead is maybe 100 km (60 miles) or less away. Near the horizon, it can be 1000 km (600 miles ) away, but would have to be intrinsically VERY bright to pass through that much atmosphere and still be seen.<br />The extinction in brightness for such an object is near 4 or 5 magnitudes.<br /><br />At slow speeds, anything could appear to stop or even move backwards, since the eye and mind can, and do play funny tricks with position. I've seen myself be fooled with Arcturus, where I thought it was moving until I got myself oriented in the sky <img src="/images/icons/smile.gif" /><br /><br />Color is hard, depending on how bright it is. The cones in your eye don't really begin to detect color until an object is ~ Mag +2 or so, so anything fainter would appear white, even if it was colored. <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>

 

[yevaud]

^ What Wayne said. ^<br /><br />Also, it's intrinsic brightness would depend on it's velocity (primarily), and a smaller extent to it's composition (which is why you see colored meteoroids).<br /><br />A simple table for this:<br /><br />Sodium is Orange-yellow<br />Iron is Yellow<br />Magnesium is Blue-green<br />Calcium is Violet<br />Silicon is Red<br /><br />Pretty basic stuff. And damned pretty to watch, too. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[MeteorWayne]

For meteors, most of what color is generated is based on the Oxygen and Nitrogen of the atmosphere that is energized. <br />Since most meteors are less than a few mm in diameter, only rarely is the particle itself much of a contributer to the light.<br /><br />Of course very bright ones (fireballs) are larger so can have color from more sources than the constituents of the atmosphere.<br /><br />But you're talking as bright as Venus before that's very likely. <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>

 

[yevaud]

Well, remember I'm talking the possibility of a reentering piece of debris.<br /><br />Satellites are plated in a thin layer of gold (to prevent oxidization). Gold doesn't plate well, it's pretty inert. It's usually electroplated onto a thin copper sheath. If a piece of satellite debris reenters, the gold and copper ionize from the reentry heat, and provide you with a beautiful blue or green color.<br /><br />Of Meteorites, Nickel Iron and Carbonaceous Chondrites with impurities can make some nice colors. You've seen them, certainly. If anyone here, you would have. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[MeteorWayne]

Yes, man made objects are constructed of many more color producing materials than the natural fluff of the solar system.<br />So are fireworks, and many of the same substances (though I suspect gold is used rarely on the 4th of July <img src="/images/icons/smile.gif" /> ). They also are generally brighter, so make whatever color is created more easily visible. Also the slower speed gives more time for the mind to absorb the input. <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>

 

[yevaud]

Did you get a chance to see any of the Shoemaker-Levy impacts into Jupiter? The one I saw, coming around the limb of the planet after it had impacted, was spectacular. Red/orange/yellow, in a dome-shape. Or so it appeared in my school's telescope. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[mrtuft]

Roughly east to west.

 

[MeteorWayne]

Regrettably no.<br />My life was in a non-astronomical phase then, of all the luck. I had a gap from about 90-96 where I let other stuff get in the way.<br />What a maroon! <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>