IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Earths 2nd Moon?
Guest_spaceffm_*
post Nov 14 2005, 10:22 PM
Post #1





Guests






I thought about it a lot.
Do U think it would be possible that Earths gravity catches someday an asteroid or something similar and would keep it as 2nd moon?

What precondition would be absolutly necessary?
WQould it be possible at all due to both gravitational fields of earth and moon?

Wouldn't it be fantastic to have a 2nd small moon?

Thx for sharing your thoughts in this matter...
Go to the top of the page
 
+Quote Post
djellison
post Nov 14 2005, 10:35 PM
Post #2


Administrator
****

Group: Chairman
Posts: 13709
Joined: 8-February 04
Member No.: 1



We have one called Cruithne I believe - something like that

Doug
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post Nov 14 2005, 10:36 PM
Post #3





Guests






It would certainly be possible, thanks to three-body gravitational effects -- that is, the gravitational effect of the Sun slows down the rate at which an asteroid passes the Earth (during their separate orbits around the Sun) to the point that it can drift into orbit around Earth without the need for any disturbing impact or friction. But this requires very specific conditions; the zone in which it can take place is seriously limited.

Still, it does happen -- Jupiter, whose three-body capture zone is much wider, regularly captures comets as temporary satellites in highly elliptical orbits and and then releases them at a later apoapsis. (In the case of Shoemaker-Levy 3, one such comet actually crashed into Jupiter at its periapsis, although that happens only about once a millennium.) And I seem to remember reading somewhere calculations that one small near-Earth asteroid may have been briefly captured a few centuries ago. The possibility cannot quite be ruled out yet that our own Moon was captured that way, rather than being created by the debris from a glancing impact -- Harrison Schmitt, at any rate, is still holding out for that alternative theory. But the odds, to repeat, are very long.
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post Nov 14 2005, 10:38 PM
Post #4





Guests






Cruithne, however, isn't a "moon", but just an asteroid locked into a 1:1 orbital-period resonance with Earth ( http://burtleburtle.net/bob/physics/cruithne.html ). Also, it's Shoemaker-Levy 9 -- not "3" -- that hit Jupiter.
Go to the top of the page
 
+Quote Post
Bob Shaw
post Nov 14 2005, 10:43 PM
Post #5


Senior Member
****

Group: Members
Posts: 2488
Joined: 17-April 05
From: Glasgow, Scotland, UK
Member No.: 239



A couple of years ago there was a brief flurry when a second 'moon' did turn up - it turned out, however, to be the S-IVB stage from the Apollo 12 Saturn V, which had entered Solar orbit and been recaptured within the Earth-Moon system (not on a permanent basis, however). In true scientific detective-novel fashion, it was discovered to be the spent spacecraft booster as a result of spectral analysis, which revealed a surface coating of, er, Titanium Oxide - as in white paint!

Bob Shaw


--------------------
Remember: Time Flies like the wind - but Fruit Flies like bananas!
Go to the top of the page
 
+Quote Post
tasp
post Nov 15 2005, 03:09 AM
Post #6


Member
***

Group: Members
Posts: 885
Joined: 30-January 05
Member No.: 162



Toro!

Funny little asteroid that was in resonance with Venus, and now is in a resonance with Earth.

Yet another way objects can have relationships in our amazing solar system.
Go to the top of the page
 
+Quote Post
silylene
post Nov 15 2005, 03:28 AM
Post #7


Junior Member
**

Group: Members
Posts: 84
Joined: 24-November 04
Member No.: 111



Two other asteroids, 1998 UP1 and 2000 PH5 are also locked into resonance with Earth, with orbits not unlike Cruithne.
Go to the top of the page
 
+Quote Post
mike
post Nov 15 2005, 05:29 PM
Post #8


Member
***

Group: Members
Posts: 350
Joined: 20-June 04
From: Portland, Oregon, U.S.A.
Member No.: 86



Some might say that Earth is Cruithne's moon.
Go to the top of the page
 
+Quote Post
ljk4-1
post Nov 15 2005, 05:57 PM
Post #9


Senior Member
****

Group: Members
Posts: 2454
Joined: 8-July 05
From: NGC 5907
Member No.: 430



QUOTE (Bob Shaw @ Nov 14 2005, 05:43 PM)
A couple of years ago there was a brief flurry when a second 'moon' did turn up - it turned out, however, to be the S-IVB stage from the Apollo 12 Saturn V, which had entered Solar orbit and been recaptured within the Earth-Moon system (not on a permanent basis, however). In true scientific detective-novel fashion, it was discovered to be the spent spacecraft booster as a result of spectral analysis, which revealed a surface coating of, er, Titanium Oxide - as in white paint!

Bob Shaw
*


Don't forget "Planetoid" 1991 VG:

http://www.centauri-dreams.org/?p=80


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

Go to the top of the page
 
+Quote Post
blobrana
post Dec 6 2005, 08:17 PM
Post #10


Junior Member
**

Group: Members
Posts: 45
Joined: 8-August 05
Member No.: 457



QUOTE (ljk4-1 @ Nov 15 2005, 10:27 PM)
Don't forget "Planetoid" 1991 VG:


Hum,
1991 VG was the rocket body...

Anyway don`t forget 2003 YN107



and 2002 AA29
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 1st August 2014 - 07:48 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.