# Comet near the sun whose orbit is?

#### dolphinsny

A comet near the sun whose orbit is________ would never be near the sun again is called what? My options are elliptical (I know its not this one), circular, hyperbolic, apogee, and following an inverse square law.

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#### davenn

Gold Member
think about the shape of a circular orbit and of a hyperbolic orbit

if you dont know what hyperbolic means, google it :)
Also google apogee and you will discover the meaning of that ... ie. it isnt a type of orbit.

Tell us what you discover.

#### HallsofIvy

Homework Helper
"apogee" doesn't apply here. It is a point on an orbit (about the earth, not the sun), not a description of an orbit. And "following an inverse square law" is true of any orbit.

"apogee" doesn't apply here. It is a point on an orbit (about the earth, not the sun), not a description of an orbit. And "following an inverse square law" is true of any orbit.
I once knew a guy from online who'd renounced plate tectonics in favor of a "Growing Earth" theory. Part of his theory was that the gigantic reptiles/birds of the dinosaur age were the result of the lesser gravitational pull upon objects at Earth's surface due to the then-smaller diameter of Earth. When I tried to explain to him that a smaller diameter of Earth would have produced a greater, rather than a lesser, gravitational pull upon objects at Earth's surface, he derided me for being so "hung up on that inverse square of the distance thing"!!!!

He did, however, offer no counterargument to that "Newtonian Gravity Equation thing".

He cut off the dialogue with me when I tried to explain that, as there have been supercontinents prior to Pangea, the "Growing Earth" theory is actually the "Oscillating Earth Volume" theory, with no explanation as to the oscillating energy source which would be required to produce this effect.

***

Anyways, a comet or other object that would pass by the sun once and never again is not a satellite of the sun, but a transient object passing through the Solar System, as the velocity required to produce this effect would have to be sufficient to allow the object to pass by the sun without deceleration due to the sun's gravitational tug at perihelion reducing the object's velocity below Solar System Escape Velocity, which means the object would escape out into interstellar space. That is, assuming no source of motive energy to the "orbiting" body, as increased orbital amplitude requires an increase in the velocity (read: kinetic energy) of the orbiting body. (And, PLEASE don't argue the thrust effect of sublimating cometary ices, as these are too small to generate perturbations in orbital velocity/amplitude sufficient to change the object's course to the degree necessary to achieve the results of which the original post spoke.)

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#### davenn

Gold Member
dont give the answers outright guys ;)

Im hoping the OP will discover some conclusions for themselves
and report back

Dave

#### tiny-tim

Homework Helper
… a comet or other object that would pass by the sun once and never again is not a satellite of the sun, but a transient object passing through the Solar System …
it's perfectly possible for a comet, or even a planet, formerly orbiting the sun, to be involved in a collision, or in a "slingshot" encounter with a large planet, which puts it into an orbit which takes it out of the solar system never to return

it's perfectly possible for a comet, or even a planet, formerly orbiting the sun, to be involved in a collision, or in a "slingshot" encounter with a large planet, which puts it into an orbit which takes it out of the solar system never to return
That's true, such an encounter could put the object on a trajectory that could take it out of the Solar System, but such a trajectory would not be an orbit, but an escape trajectory. Besides, my answer includes the sentence: "That is, assuming no source of motive energy to the "orbiting" body, as increased orbital amplitude requires an increase in the velocity (read: kinetic energy) of the orbiting body. ". The OP speaks specifically of an orbital track which would accomplish that feat, and makes no mention of collisions or near passes.

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#### Integral

Staff Emeritus
Gold Member
I once knew a guy from online who'd renounced plate tectonics in favor of a "Growing Earth" theory. Part of his theory was that the gigantic reptiles/birds of the dinosaur age were the result of the lesser gravitational pull upon objects at Earth's surface due to the then-smaller diameter of Earth. When I tried to explain to him that a smaller diameter of Earth would have produced a greater, rather than a lesser, gravitational pull upon objects at Earth's surface, he derided me for being so "hung up on that inverse square of the distance thing"!!!!

He did, however, offer no counterargument to that "Newtonian Gravity Equation thing".

He cut off the dialogue with me when I tried to explain that, as there have been supercontinents prior to Pangea, the "Growing Earth" theory is actually the "Oscillating Earth Volume" theory, with no explanation as to the oscillating energy source which would be required to produce this effect.

***

Anyways, a comet or other object that would pass by the sun once and never again is not a satellite of the sun, but a transient object passing through the Solar System, as the velocity required to produce this effect would have to be sufficient to allow the object to pass by the sun without deceleration due to the sun's gravitational tug at perihelion reducing the object's velocity below Solar System Escape Velocity, which means the object would escape out into interstellar space. That is, assuming no source of motive energy to the "orbiting" body, as increased orbital amplitude requires an increase in the velocity (read: kinetic energy) of the orbiting body. (And, PLEASE don't argue the thrust effect of sublimating cometary ices, as these are too small to generate perturbations in orbital velocity/amplitude sufficient to change the object's course to the degree necessary to achieve the results of which the original post spoke.)
Assuming, as mentioned in previous posts that there are no modifications to the body's path then what is written above needs clarification. An object which enters the solar system with some speed, will "fall" under gravitational influence of the sun, make an single pass of the sun, then exit the solar system with the SAME speed with which it entered.

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