Orbiting the Sun beyond the Hill sphereby xpell Tags: hill sphere, langrangian points, solar orbits 

#1
Feb1813, 10:21 PM

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I was wondering if a spacecraft (or any other object) could 'coorbit' the Earth by orbiting the Sun beyond our Hill sphere. For example, could this object 'hover over' the North (or South) Pole at >1,500,000 km?
Thanks in advance! 



#2
Feb1913, 04:20 AM

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hi xpell!
yes, see http://en.wikipedia.org/wiki/Lagrangian_point (one theory of the origin of the moon is that it formed from the collision of the earth with a another body orbiting near the L4 or L5 Lagrangian point, see http://en.wikipedia.org/wiki/Giant_i...rigin_of_Theia) 



#3
Feb1913, 10:27 AM

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Well shoot. That response was too short. No, it can't. 



#4
Feb1913, 12:02 PM

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Orbiting the Sun beyond the Hill sphere 



#5
Feb1913, 01:03 PM

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#6
Feb1913, 01:31 PM

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I am actually not so interested in the spacecraft or asteroid thing as in understanding if the Hill sphere is the absolute limit of a body's gravitational influence or you must still need to take it into account. 



#7
Feb1913, 02:08 PM

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There is no absolute limit of influence. Even the planets influence each other in a measurable way. The Hill sphere gives the opposite: Outside the hill sphere (or close to it), you have to take the third object (here: sun) into account, while you can neglect it for objects deep inside (like low earth orbits). So yes, you have to take earth into account. But a mission for a few weeks with that trajectory looks possible. On the other hand, take two satellites in eccentric orbits, and you get observations with much better resolution for years.



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