The shape of our solar system's orbits.

In summary, the conversation discusses the shape of planets' orbits in our solar system, with one source stating that they are elliptical and another mentioning that our solar system is one of the few known systems with round orbits. However, further analysis shows that the majority of exoplanets have elliptical orbits, with only 30% matching the solar system's average eccentricity. The conversation also delves into the potential factors that could influence the shape of orbits in different systems. Finally, there is a brief tangent about the nature of orbits, with one person stating that all orbits are spiral.
  • #1
PrincePhoenix
Gold Member
116
2
What's the shape of the planets orbiting the sun in our solar system according to this website
http://www.chacha.com/question/what-is-the-shape-of-orbit-of-planets
they are elliptical. But in a documentary (maybe history channel's "The Universe", but I'm not sure) I heard that our solar system is one of the few known systems with round orbits.Majority of the others have elliptical. So what's the truth?
 
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  • #2
PrincePhoenix said:
What's the shape of the planets orbiting the sun in our solar system according to this website
http://www.chacha.com/question/what-is-the-shape-of-orbit-of-planets
they are elliptical. But in a documentary (maybe history channel's "The Universe", but I'm not sure) I heard that our solar system is one of the few known systems with round orbits.Majority of the others have elliptical. So what's the truth?

Isn't an elliptical orbit not rounded?
 
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  • #3
I mean "round" not "rounded"?
 
  • #4
The truth is that for 7 out of the 8 planets the SS's orbits are very nearly circular.

Mercury's, Pluto's and Sedna's orbits are more elliptical.


Here is a list of all extrasolar planets currently known.
http://exoplanet.eu/catalog-all.php?&munit=&runit=&punit=&mode=5&more=
You can even sort on the Eccentricity column (Ecc). Eccentricity is a ratio if ellipticality of the orbit (zero is perfectly circular.)
 
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  • #5
Note that a circle is just a special case of an ellipse: all orbits are elliptical.
 
  • #6
russ_watters said:
Note that a circle is just a special case of an ellipse: all orbits are elliptical.

That's what I was trying to get at in my previous post I guess I should have worded it more like: Can't elliptical orbits be round?

Now that I've reread what I said before it does sound kind of funny haha.
 
  • #7
A quick calculation shows that the average eccentricity of our SS's 8 major planets is ~0.0606
while the average of the 345 extrasolar planets with known eccentricities is ~0.2181
or about 3.5 times more eccentric.
 
  • #8
But does that tell us about the extrasolar planet orbits or about the extrasolar planet detection mechanism?
 
  • #9
Vanadium 50 said:
But does that tell us about the extrasolar planet orbits or about the extrasolar planet detection mechanism?
No doubt that's a factor.

But there are about 55 or so planets whose eccentricity is listed as unknown. I did not include those ones. Since 'unknown' is explicitly listed, it was a reasonable assumption that the listed values are trustworthy enough for a rough calculation.

It is a big assumption, I grant.
 
  • #10
DaveC426913 said:
A quick calculation shows that the average eccentricity of our SS's 8 major planets is ~0.0606
while the average of the 345 extrasolar planets with known eccentricities is ~0.2181
or about 3.5 times more eccentric.

The average does not give the complete picture. If you run the data through a frequency analysis, about 1/3 of the observed eccentricities are less than 0.05 (approximately the solar system average) and around 2/3 are less than 0.2.

The above doesn't take the distance of an exoplanet from its star into account and its conceivable that planets within different AU ranges could show different means. Furthermore, and this is purely conjecture on my part, it is possible that exoplanets with larger eccentricities are the larger gas giants and thus easier to observe. The data may be inherently biased by our current observational limitations.

In any case, if 30% of the observed exoplanets match the solar system average, then the solar system cannot be considered to be that unique.
 
  • #11
talk2envy said:
The average does not give the complete picture. If you run the data through a frequency analysis, about 1/3 of the observed eccentricities are less than 0.05 (approximately the solar system average) and around 2/3 are less than 0.2.

The above doesn't take the distance of an exoplanet from its star into account and its conceivable that planets within different AU ranges could show different means. Furthermore, and this is purely conjecture on my part, it is possible that exoplanets with larger eccentricities are the larger gas giants and thus easier to observe. The data may be inherently biased by our current observational limitations.

In any case, if 30% of the observed exoplanets match the solar system average, then the solar system cannot be considered to be that unique.

That's why I said "quick calculation" rather than "exhaustive calculation".

But you're right. The OP's post states "... our solar system is one of the few known systems with round orbits. Majority of the others have elliptical."

...which is clearly not what the data is showing when analyzed more carefully than a simple average.
 
  • #12
talk2envy said:
In any case, if 30% of the observed exoplanets match the solar system average, then the solar system cannot be considered to be that unique.

It could be. If the you have 30% of the exoplanets match the solar system average, and the eccentricities are random, then the odds of have eight planets all with more or less round orbits is quite low. Apparently there is a resonance between Jupiter and Saturn that keeps the rest of the planets in line.

I've heard this discussed in terms of the anthropic principle. Why are solar system orbits rather round? Because if they weren't we wouldn't be seeing them.
 
  • #13
twofish-quant said:
It could be. If the you have 30% of the exoplanets match the solar system average, and the eccentricities are random, then the odds of have eight planets all with more or less round orbits is quite low.

True but only if the eccentricity of each exoplanet is determined independently.

Apparently there is a resonance between Jupiter and Saturn that keeps the rest of the planets in line.

This argument could actually extend to other systems. Current observations very likely detect the largest object(s) within an extrasolar system. And if 30% of those have low eccentricities, then its possible that other smaller objects within these systems will also be forced into circular orbits.
 
  • #14
All orbits in this universe are spiral.
 
  • #15
Are you just kidding, or are you seriously saying all orbits are spiral?
 
  • #16
YES. What one isn't?
 
  • #17
Tom Kull said:
YES. What one isn't?

Why shouldn't we report you as a troll? Your statements are unjustified. Do you want to give us more information, or do you just want an argument?
 
  • #18
All satalites move about primaries that are moving also. If the positions of the two bodies were ploted over time These plots would resemble a spiral. Sorry I live in a universe that has at least four dimentions not two.
 
  • #19
Tom is thinking that, from an external reference point, the elliptical orbit coupled with proper motion of the system results in a helical path, which he is then mistakenly calling spiral.

Tom, the path a planet follows is entirely dependent on the observer's frame of reference. You have chosen the FoR that is from a body in relative motion along the axis of the solar system in which the planet is orbiting. By saying all orbits are [helical] you've mistakenly assumed a FoR reference that is somehow more valid than any other.
 
  • #20
Hard to tell what he's thinking. He might be including some very small braking effects, such as the emission of gravitational radiation (which always happens), or Poynting-Robertson drag (which is a larger effect in most circumstances but requires the orbiting body to be warmed by the body it's orbiting so that it emits radiation. Or he might just be being silly - who knows?
 
  • #21
pervect said:
Hard to tell what he's thinking. He might be including some very small braking effects, such as the emission of gravitational radiation (which always happens), or Poynting-Robertson drag (which is a larger effect in most circumstances but requires the orbiting body to be warmed by the body it's orbiting so that it emits radiation. Or he might just be being silly - who knows?
No, he doesn't mean planets are spiraling inwards; he means they're following a helix. See his post 18.

He's still under a misapprehension; but not as bad as it seems.
 
  • #22
I am not sure of the distintion between helik and spiral. positions are plotted with time as well as x,y and z but I suppose that is hard to depict on paper without using a spirograph.
 
  • #23
I took Tom's remark as a light hearted jest to remind us that all of our discussions on eccentricity revolve (pun intended) around a heliocentric perspective. (Or should that be barycentric?) I thought it was quite whimisical and was amused by graal's spontaneous hostile reaction to a suspected troll.

If science isn't fun you remove half the reason for doing it.
 
  • #24
Ophiolite said:
I took Tom's remark as a light hearted jest to remind us that all of our discussions on eccentricity revolve (pun intended) around a heliocentric perspective. (Or should that be barycentric?) I thought it was quite whimisical and was amused by graal's spontaneous hostile reaction to a suspected troll.

If science isn't fun you remove half the reason for doing it.

Must've put my "cranky pants" on that day. But it's a rather trollish thing to say isn't it?
 
  • #25
qraal said:
Must've put my "cranky pants" on that day. But it's a rather trollish thing to say isn't it?
Well, it's only trollish if he knew it were controversial. I don't think he realizes how far from reality his preconception of relative motion is.
 
  • #26
  • #28
I'm pretty sure Tom is correct about this. Most orbits (especially naturally occurring orbits) follow a spiral... I'm not 100% certain I'm going to go look it up right now.

EDIT: The orbits of the planets ALL follow a spiral. I.e. Earth is moving towards the sun albeit a very small amount it still does. So does Mars and a few other planets. A few of the planets are moving away from the Sun such as Venus and Mercury.
 
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  • #29
Since the distance is changing extremely slowly, it is overly nitpicky to bring up the spiraling here. It is not helpful to the OP.
 
  • #30
russ_watters said:
Since the distance is changing extremely slowly, it is overly nitpicky to bring up the spiraling here. It is not helpful to the OP.

Yeah this is true, I wasn't bringing up to address the OP but just to add some credibility to Tom because a few people seem to be acting pretty negatively against his comment.
 
  • #31
Bzzt. I'm callin' foul. Tom is changing his story.

He was clear - and repeated several times - that he was talking about the movement of the central body. Reread posts 18 and 22.

Now he's claiming he meant orbital regression? Hello?


Anyway:

Even if all post between 18 and 26 magivcally vaqnished and we are forced to grant his new claim, it's kind of silly to talk about "all orbits being a spiral" when there are far, far larger deviations from ellipses, such as the effects from other planets.

If I drew a freehand circularish curve on a piece of paper that had
- an eccentricity of several centimeters
- wandered back and forth from that path by several millimeters,
yet
increased its (average) diameter by only a few angstroms with each pass

would it be sensical to call that a spiral??
 
  • #32
DaveC426913 said:
Bzzt. I'm callin' foul. Tom is changing his story.

He was clear - and repeated several times - that he was talking about the movement of the central body. Reread posts 18 and 22.

Now he's claiming he meant orbital regression? Hello?


Anyway:

Even if all post between 18 and 26 magivcally vaqnished and we are forced to grant his new claim, it's kind of silly to talk about "all orbits being a spiral" when there are far, far larger deviations from ellipses, such as the effects from other planets.

If I drew a freehand circularish curve on a piece of paper that had
- an eccentricity of several centimeters
- wandered back and forth from that path by several millimeters,
yet
increased its (average) diameter by only a few angstroms with each pass

would it be sensical to call that a spiral??

Oh well I only really read his first post and then the original hostility towards him so I thought I would just jump into aid him lol. Yes it is silly to call it a spiral but it's not really wrong...
 
  • #33
Sorry! said:
... but it's not really wrong...
Sure. In the same way it's not really wrong to call it a square, either. :rolleyes:
 
  • #34
If anyone thinks 2.5 cm per year is trivial than what does that say about Hubble's law on the universe's inflation rate.

We believe that Pope Urban VIII is alive and well and lives on the internet.
 
  • #35
Tom Kull said:
If anyone thinks 2.5 cm per year is trivial
when compared to the millions - and in some cases tens of millions - of kilometers of deviations due to other factors. Don't pretend I didn't make this clear.

Besides, that still isn't what you were claiming originally. Your credibility is a bit shaky, having jumped from one train to another.

There's no shame in being mistaken and being corrected. C'mon, man up. Don't make it a bad thing by being bloody-headed about it.
 
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<h2>1. What is the shape of our solar system's orbits?</h2><p>The shape of our solar system's orbits is elliptical, meaning they are oval-shaped.</p><h2>2. What causes the shape of our solar system's orbits?</h2><p>The shape of our solar system's orbits is caused by the gravitational pull of the sun and other celestial bodies.</p><h2>3. Are all the orbits in our solar system the same shape?</h2><p>No, the orbits in our solar system can vary in shape depending on the gravitational influence of nearby planets and other objects.</p><h2>4. How does the shape of an orbit affect the planet's distance from the sun?</h2><p>The shape of an orbit does not affect the planet's distance from the sun. The distance is determined by the planet's position in its orbit, with the closest point being the perihelion and the farthest point being the aphelion.</p><h2>5. Can the shape of a planet's orbit change over time?</h2><p>Yes, a planet's orbit can change over time due to various factors such as gravitational interactions with other planets, asteroids, or comets.</p>

1. What is the shape of our solar system's orbits?

The shape of our solar system's orbits is elliptical, meaning they are oval-shaped.

2. What causes the shape of our solar system's orbits?

The shape of our solar system's orbits is caused by the gravitational pull of the sun and other celestial bodies.

3. Are all the orbits in our solar system the same shape?

No, the orbits in our solar system can vary in shape depending on the gravitational influence of nearby planets and other objects.

4. How does the shape of an orbit affect the planet's distance from the sun?

The shape of an orbit does not affect the planet's distance from the sun. The distance is determined by the planet's position in its orbit, with the closest point being the perihelion and the farthest point being the aphelion.

5. Can the shape of a planet's orbit change over time?

Yes, a planet's orbit can change over time due to various factors such as gravitational interactions with other planets, asteroids, or comets.

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