[meteorite-list] meteor trajectory inquiry

[Chris Peterson]

The sightings in this case are unusual because they are so close to the 
apparent event. As a rule, people don't see overhead meteors, so witness 
reports tend to be richest 100 miles or more away, where you see the meteor 
near the horizon (especially at times of the day, as in this case, where 
most reports come from people in cars).

I don't know what the New England weather conditions were like at the time; 
perhaps conditions outside the immediate area were not good for seeing into 
Massachusetts. The reports suggest it was cloudy.

In any case, this pattern would suggest a fairly steep descent (which itself 
makes it much less likely that any meteorites survived). Shallow descents 
cover a lot of ground, so they are usually seen over wider areas- sometimes 
over paths many hundreds of miles long.

Steep descents are associated with a rapid increase in pressure and an 
earlier breakup of the parent, making it more likely that the debris will 
burn up completely. The best scenario for meteorite production is a low 
velocity (most likely to be seen in the early evening), and a relatively 
shallow entry angle. That gives the meteoroid lots of time to slow down 
without breaking into small pieces while the speed is still very high.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: "teddy applebaum" <tiapplebaum at gmail.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Sunday, January 25, 2009 2:20 PM
Subject: [meteorite-list] meteor trajectory inquiry


> Hi list,
>
> I have been closely following the recent MA meteor sighting. I noticed
> that the numerous sightings for this particular bolide were seen only
> over a relatively small area. Does this point to the meteor having a
> more vertical trajectory in comparison to the atmosphere? In short do
> localized sightings tend to mean a steeper trajectory?
>
> Along this line of thought, do steeper trajectories mean an increased
> chance that material reached the ground since atmospheric ablation
> would occur for a shorter time? Any input would be appreciated - Teddy