Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Do Meteors Orbit Earth?

  • Please log in to reply
13 replies to this topic

#1 Brian Albin

Brian Albin

    Seeker

  • -----
  • topic starter
  • Posts: 1,126
  • Joined: 22 Aug 2006
  • Loc: Western Oregon

Posted 21 September 2021 - 09:51 PM

As a meteor arrives at Earth, does it fall into a decaying orbit before eventually coming low enough to be seen burning in our atmosphere?  Or does it fall to Earth more directly, without orbiting?

 

Brian



#2 ngc7319_20

ngc7319_20

    Vanguard

  • *****
  • Posts: 2,420
  • Joined: 25 Oct 2015
  • Loc: MD

Posted 21 September 2021 - 09:57 PM

Directly



#3 ButterFly

ButterFly

    Mercury-Atlas

  • *****
  • Posts: 2,553
  • Joined: 07 Sep 2018

Posted 21 September 2021 - 10:48 PM

Everything in the solar system orbits around the center of mass of the Solar System, which is practically the Sun.  Everything that collides with the Earth has its orbit around the Sun perturbed by the Earth's gravity.  It is very, very unlikley that something will be coming directly at the Earth.  Everything in orbit around the Sun follows Kepler's laws, one of which is R cubed over T squared is constant.  If it's coming from outside, it's moving slower - from inside, faster.  The only way it comes directly at the Earth is if it is in Earth's orbit and orbiting in the opposite direction.

 

Very few asteroids get captured by the Earth's gravity.  The first one we know about was only recorded a few years ago.  These orbits are very unstable and are more likely to get ejected by the Sun and Moon's gravity.

 

As soon as an asteroid (or comet, or satellite) hits some atmosphere, its orbit decays.  Spy satellites, for example, can orbit at about 200km from the surface.  Their orbits are constantly decaying, so they need station keeping boosts every now and then to stay up and avoid getting into more dense atmosphere that can cause damage.  They eventually run out of fuel and are express shipped to a graveyard in the Pacific.

 

So without a doubt, anything that makes its way to the Earth has its orbit perturbed by Earth's gravity, then decayed by the atmosphere.


  • ShaulaB and Benschop like this

#4 Sleep Deprived

Sleep Deprived

    Viking 1

  • *****
  • Posts: 851
  • Joined: 17 Apr 2019
  • Loc: Seattle Area

Posted 21 September 2021 - 11:32 PM

Another thing to consider which may help answer your question, is a meteor shower.  The Earth goes through a stream of comet dust and it shows up as a meteor shower that has a radiant.  The radiant is a point in the sky where all the shooting stars seem to emanate from.  If any of these meteors were getting caught in Earth's gravity field and orbiting  a couple times (or even a small bit of an orbit), we would be seeing the the meteors in the shower coming from different spots in the sky - we would even see them at locations on the other side of the Earth.  If this happened a lot, the idea of a 'radiant' wouldn't hold very well.

 

All that is not to say that such things never happen.  I expect they are quite rare, though.


  • Brian Albin, ShaulaB and ButterFly like this

#5 ButterFly

ButterFly

    Mercury-Atlas

  • *****
  • Posts: 2,553
  • Joined: 07 Sep 2018

Posted 21 September 2021 - 11:43 PM

1913 Great Meteor Procession is the most detailed possible such phenomenon.  How cool would that be to see?

 

Earth Trojan is a good place to start, then follow through the links to horeshoe, temporary satellite, quasi ... .  Notice that the temporary satellites have all been Apollos.  They need to be relatively slow enough to stick around and get captured, so their orbits are similar to Earth's.


  • dave253 likes this

#6 Brian Albin

Brian Albin

    Seeker

  • -----
  • topic starter
  • Posts: 1,126
  • Joined: 22 Aug 2006
  • Loc: Western Oregon

Posted 22 September 2021 - 09:23 PM

I thank you all for your answers.

Brian



#7 KBHornblower

KBHornblower

    Viking 1

  • -----
  • Posts: 941
  • Joined: 01 Jul 2020
  • Loc: Falls Church, VA (Washington DC suburb)

Posted 29 September 2021 - 06:39 PM

For the short stretch near Earth we can go geocentric and analyze the meteoroid's motion as a hyperbolic orbit around Earth.  For one destined to plunge steeply into the atmosphere the perigee of that path is below the ground.  If it stays above the atmosphere it will fly by and end up in a heliocentric orbit that is different from what came before the encounter.

 

In the absence of atmospheric drag, it is impossible to capture the meteoroid into a tightly closed orbit around Earth without the gravity of another nearby body.


  • ButterFly likes this

#8 spacemunkee

spacemunkee

    Fly Me to the Moon

  • *****
  • Posts: 6,170
  • Joined: 22 Oct 2017
  • Loc: Cincinnati, Ohio

Posted 29 September 2021 - 07:01 PM

I'm going to say without getting to 'sciency'wink.gif , speed, mass/composition, direction, gravity influence from where ever, turtles, solar wind, all play a role..(is that to 'sciency?)lol.gif

 

But I'm going to say, never 'perfectly' straight on..smile.gif



#9 Keith Rivich

Keith Rivich

    Gemini

  • *****
  • Posts: 3,067
  • Joined: 17 Jun 2011
  • Loc: Cypress, Tx

Posted 30 September 2021 - 04:00 PM

Meteors are traveling so fast that unless they hit the earth they just fly right by. 



#10 Sleep Deprived

Sleep Deprived

    Viking 1

  • *****
  • Posts: 851
  • Joined: 17 Apr 2019
  • Loc: Seattle Area

Posted 30 September 2021 - 05:14 PM

Meteors are traveling so fast that unless they hit the earth they just fly right by. 

You make a good point.  The gas giants each have a corral of moons, and many of them may have started out as asteroids.  Some of them also have asteroids at their LaGrange Points ahead and behind in their orbits.  Being much smaller, and in the inner part of the Solar System, that is much harder for Earth to do.  Jupiter is The Big Attractor - it affects orbits of all kinds of little bits from far away (Earth, not so much).  Plus, it likely 'corralled' the asteroids in the asteroid belt while it moved towards the Sun in the earliest part of our history - so it had 'close contact' with many more asteroids.  For every million (billion??) asteroids that had a close call with Jupiter, maybe one 'stuck' and ended up in orbit around Jupiter or at one of its Lagrange Points after interaction with other bodies (moons of Jupiter).

 

Although it is POSSIBLE for Earth to have orbiting asteroids, it is not nearly as likely as Jupiter due to size differences, position in the Solar System (being in the 'busy' inner Solar System means that Earth's long distance influence is very great), number of moons (to slow incoming bodies enough to get into orbit, rather than simply fly on by), and probably a few other factors.  Because the Moon is so big (bigger by ratio than any other planet's moon), any body lucky enough to take up orbit around Earth will likely be in an unstable orbit.  A teeny-tiny moon around Earth?  Possible short-term, but not likely long-term due to the instabilities listed.



#11 Keith Rivich

Keith Rivich

    Gemini

  • *****
  • Posts: 3,067
  • Joined: 17 Jun 2011
  • Loc: Cypress, Tx

Posted 30 September 2021 - 08:05 PM

You make a good point.  The gas giants each have a corral of moons, and many of them may have started out as asteroids.  Some of them also have asteroids at their LaGrange Points ahead and behind in their orbits.  Being much smaller, and in the inner part of the Solar System, that is much harder for Earth to do.  Jupiter is The Big Attractor - it affects orbits of all kinds of little bits from far away (Earth, not so much).  Plus, it likely 'corralled' the asteroids in the asteroid belt while it moved towards the Sun in the earliest part of our history - so it had 'close contact' with many more asteroids.  For every million (billion??) asteroids that had a close call with Jupiter, maybe one 'stuck' and ended up in orbit around Jupiter or at one of its Lagrange Points after interaction with other bodies (moons of Jupiter).

 

Although it is POSSIBLE for Earth to have orbiting asteroids, it is not nearly as likely as Jupiter due to size differences, position in the Solar System (being in the 'busy' inner Solar System means that Earth's long distance influence is very great), number of moons (to slow incoming bodies enough to get into orbit, rather than simply fly on by), and probably a few other factors.  Because the Moon is so big (bigger by ratio than any other planet's moon), any body lucky enough to take up orbit around Earth will likely be in an unstable orbit.  A teeny-tiny moon around Earth?  Possible short-term, but not likely long-term due to the instabilities listed.

Earth orbiting asteroids are more common then you think. Every few years one gets discovered and posted on the MPML forum. I don't fully understand their orbits, they tend to be horse shoe shaped, very complex, and very temporary, usually just a few orbits before being ejected. 


  • Brian Albin and ButterFly like this

#12 ButterFly

ButterFly

    Mercury-Atlas

  • *****
  • Posts: 2,553
  • Joined: 07 Sep 2018

Posted 04 October 2021 - 04:24 AM

For the short stretch near Earth we can go geocentric and analyze the meteoroid's motion as a hyperbolic orbit around Earth.  For one destined to plunge steeply into the atmosphere the perigee of that path is below the ground.  If it stays above the atmosphere it will fly by and end up in a heliocentric orbit that is different from what came before the encounter.

 

In the absence of atmospheric drag, it is impossible to capture the meteoroid into a tightly closed orbit around Earth without the gravity of another nearby body.

Or you can do it properly and use the Gauss planetary equations, with drag, if and when it hits atmosphere.

 

BTW, that tiny meteoroid exerts the same force on Earth that Earth does on it!  That's Newton's Third Law.  The Gauss PEs show why Earth doesn't careen off course like the meteoroid does.  It's heavier, and thus has greater orbital angular momentum.



#13 ButterFly

ButterFly

    Mercury-Atlas

  • *****
  • Posts: 2,553
  • Joined: 07 Sep 2018

Posted 04 October 2021 - 04:26 AM

Earth orbiting asteroids are more common then you think. Every few years one gets discovered and posted on the MPML forum. I don't fully understand their orbits, they tend to be horse shoe shaped, very complex, and very temporary, usually just a few orbits before being ejected. 

See the list in Earth Trojans linked above.  Follow through the links to learn the difference between a temporary satellite, a quasi-satellite, and a horseshoe orbit.



#14 ButterFly

ButterFly

    Mercury-Atlas

  • *****
  • Posts: 2,553
  • Joined: 07 Sep 2018

Posted 04 October 2021 - 04:40 AM

In the absence of atmospheric drag, it is impossible to capture the meteoroid into a tightly closed orbit around Earth without the gravity of another nearby body.

That's mostly the Sun, rather than the Moon, quite counterintuitively.

 

See Hill Sphere for more. 
 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics