Why does a comet get pushed away by the sun when it gets too close?

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Discussion Overview

The discussion revolves around the dynamics of a comet's motion in relation to the sun, particularly why a comet appears to be pushed away when it approaches the sun. Participants explore concepts related to gravitational forces, energy potential, and the effects of solar wind on a comet's tail.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the comet's motion is influenced by the conversion of potential energy into kinetic energy as it approaches the sun, which may provide it with sufficient velocity to escape the sun's gravitational pull.
  • Others argue that the sun does not push the comet away, but rather that the gravitational pull is insufficient to keep the comet in orbit as it moves closer.
  • There is a mention of the solar wind affecting the comet's tail, with some participants proposing that the tail is actively blown away by this solar wind, while others clarify that the tail lags behind the comet.
  • A distinction is made between the ion tail and the dust tail of the comet, with the ion tail pointing directly away from the sun and the dust tail following the comet's orbital path.
  • One participant expresses skepticism about the comparison made in a textbook regarding the repulsion of atomic nuclei and the comet's motion, suggesting it is a poor analogy.

Areas of Agreement / Disagreement

Participants express differing views on the mechanics of a comet's motion and the role of solar wind, indicating that there is no consensus on the explanations provided.

Contextual Notes

Some claims rely on assumptions about gravitational dynamics and the effects of solar wind, which may not be fully explored or agreed upon in the discussion.

-e^ipi
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This was shown in a textbook about the two body problem, and they compared it to the energy potential of two atoms, but the sun and comet don't experience charge so that 'when it gets too close the nuclei repel each other'.
It mentioned something about centrifugal force, but I don't understand where that comes into play.
Thanks!
 
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The comet isn't pushed away at all.

Rather, the sun isn't able to pull it strongly enough to prevent the comet from leaving the system.
 
There is a very slight "solar wind" consisting of particles expelled by the sun. That is what causes the lighter particles of a comet's tail to lag behind it. But the effect is far too small to even slow down the comet itself noticably and even the tail only "lags"- it still follows the comet around the sun.
 
I haven't checked on this but I was under the impression that the tail of a comet is not so much 'left behind' as actively 'blown away' by the solar wind?

The result being that it mostly points away from the sun rather than along the path of the comet.
 
You should be clear to distinguish between the ion tail and the dust tail. The ion tail points directly away from the sun while the dust trail rather roughly traces the orbital motion.
 
I doubt the text stated that the way in which a Meteor moves away from the Sun is similar to the way nuclei repel each other. The two nuclei repel each other due to charge but the reason why the comet moves away from the sun is because as it moves towards the sun it converts potienial energy into kinetic energy causing it to move faster giving it the velocity and centrifugal force (<there you go) to avoid falling into the sun.

Hope this helps :)
 
-e^ipi said:
they compared it to the energy potential of two atoms, ... 'when it gets too close the nuclei repel each other'.Thanks!

Sounds like a thoroughly bad book to me, throw it away.
 

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