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Author Topic: Why are there so many meteor showers throughout the year?  (Read 1719 times)

Offline GlentoranMark

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A meteor shower is debris from a comet? Correct?

I'm just wondering why we see so many in a year? Surely the chances of a comet passing the Earth's orbit are pretty slim but yet the debris from Comet Halley manifests itself in the form of the Orinids. Does that mean Halley has a chance of impacting us some day before it evaporates? There are at least a dozen major showers every year which means as many comets have crossed out path? Isn't this a statistical anomaly?

I'm wondering has any inter planetary spacecraft crossed the path of any cometary debris? As a comet doesn't usually follow the plane of our solar system then surely the solar system should be riddled with cometary debris - especially the inner Solar System? Does the Messenger and the Spacecraft around Venus pick up any increase in activity?


 

Offline evan_au

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Re: Why are there so many meteor showers throughout the year?
« Reply #1 on: 24/10/2012 12:01:08 »
In its 1910 flyby, the Earth passed through the tail of Halley's comet: http://www.wired.com/thisdayintech/2009/05/dayintech_0519/

Of course, a visible tail which is 24 million miles long sweeps through an enormous volume of space, and we are much more likely to pass through the tail than to strike the cometary nucleus.

Dust which boils off the comet takes little energy to spread around the path of the comet's orbit, taking up far more volume than the visible tail. Add in perturbation from solar wind, solar radiation and interactions with Earth and other planets, and this dust spreads out over a large volume of space. So we see an annual meteor shower as Earth passes through this large volume.

Some meteor showers are associated with known visible comets. But long after the volatiles have all evaporated from the comet, leaving no visible "tail", the expanding cloud of dust still roughly follows the original trajectory; so many of the meteor showers come from extinct comets.

This article has a nice photo of a meteor shower from space. http://en.wikipedia.org/wiki/Meteor_shower#The_origin_of_meteoroid_streams
 

Offline evan_au

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Re: Why are there so many meteor showers throughout the year?
« Reply #2 on: 24/10/2012 21:29:57 »
Meteor showers represent a slight risk to satellites and interplanetary spacecraft.

We may see two meteorites within a minute, but these are spread out over 1,000 square kilometers of upper atmosphere - the satellite just presents a smaller target. One meteorite the size of a grain of sand striking a satellite could do significant damage (as could one too small to create a visible flash).

One year NASA ran a competition to identify the most useful science that could be conducted while orienting the Hubble telescope to present the minimum risk of being struck during a meteor shower. This is one of the outcomes: http://www.scienceiq.com/Facts/ARingAroundaDyingStar.cfm
 

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Re: Why are there so many meteor showers throughout the year?
« Reply #2 on: 24/10/2012 21:29:57 »

 

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