Why the Earth orbits around the Sun

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Discussion Overview

The discussion centers around the reasons for the Earth's orbit around the Sun, exploring concepts of gravitational forces, orbital mechanics, and the influence of other celestial bodies. Participants delve into the nature of orbits, including the effects of other planets and the barycenter of the solar system.

Discussion Character

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

Main Points Raised

  • Some participants propose that the Earth orbits the Sun due to centripetal force, while also noting that gravitational influences from other planets and space dust could affect this motion.
  • Others clarify that the Earth's orbit is elliptical and is perturbed by the gravity of other planets, although the effect of dust is considered minimal.
  • A participant questions why larger planets like Jupiter do not significantly affect Earth's orbit, leading to explanations about distance and mass ratios.
  • There is a discussion about the center of mass of the Earth-Sun system, with some participants emphasizing that both bodies orbit around this center, which is located within the Sun.
  • Several participants inquire about the current position of the solar system barycenter, noting that it is influenced by the positions of Jupiter and Saturn, with Earth having a negligible effect.
  • One participant mentions the potential existence of other large objects beyond Neptune, which could alter the barycenter's position, and shares a simulation tool for exploring these dynamics.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the factors influencing the Earth's orbit, including the roles of other planets and the barycenter. The discussion remains unresolved on some points, particularly concerning the effects of distant celestial bodies.

Contextual Notes

Some claims depend on assumptions about the existence of other planets beyond Neptune, and the discussion includes various estimates and simulations that may not account for all variables.

kenny1999
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As far as I know, the Earth orbits around the Sun because of the centripetal force
, and as far as I know, friction and gravitation from other planets should affect the circular motion of the Earth and so the path of the Earth should not be necessary that perfect.

In addition, there must be small particles or dust in the space so that there must
be friction which should also affect the circular motion of the Earth

Am I right or wrong??
 
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The Earth's orbit is an ellipse. The orbit is perturbed by other planets gravity. Dust, etc. has a much smaller effect.
 
mathman said:
The Earth's orbit is an ellipse. The orbit is perturbed by other planets gravity. Dust, etc. has a much smaller effect.

But we have some planets e.g. Jupitar that are much bigger than our Earth and not really so far away. Why don't they affect our orbit??
 
Jupiter is much farther away than the Sun, and just has 1/1000 the mass. It perturbs the orbit in a measurable way, but the effect is very small. More than 99.8% of the mass of the solar system is in the sun.
 
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kenny1999 said:
As far as I know, the Earth orbits around the Sun ...
Just to be sure you understand the full technical detail, it is not quite correct to say that the Earth orbits around the sun but rather that that both orbit around the center of mass of the two bodies (which is deep inside the sun). In day to day terms, we do say that the Earth orbits the sun.
 
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phinds said:
Just to be sure you understand the full technical detail, it is not quite correct to say that the Earth orbits around the sun but rather that that both orbit around the center of mass of the two bodies (which is deep inside the sun). In day to day terms, we do say that the Earth orbits the sun.

Just out of interest, how far from the nucleus of the Sun is the Solar System Barycentre right now?
 
Jim60 said:
Just out of interest, how far from the nucleus of the Sun is the Solar System Barycentre right now?
Close to the surface of sun, it will be outside the sun starting beginning of 2017. https://qph.is.quoracdn.net/main-qimg-118a1175c48f6ff2afd0183dd0040dd4?convert_to_webp=true (2016 is at the right side of the sun, the radius of the sun is about 700,000 km).

The difference is mainly driven by the position of Jupiter and Saturn, Earth has a negligible effect (~500 km).
 
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Jim60 said:
Just out of interest, how far from the nucleus of the Sun is the Solar System Barycentre right now?
About 280 miles is the effect of Earth, like mfb said, the bigger planets have a much large effect: http://www.applet-magic.com/centermass.htm
 
Jim60 said:
Just out of interest, how far from the nucleus of the Sun is the Solar System Barycentre right now?
Any answer assumes there are no other planets orbiting beyond Neptune. If Planet 9 and or other large objects exist beyond Neptune, this will shift the ss barycenter.

Assuming they don't exist, here's a simulation you can run to show you how the solar system barycenter changes with time. You can delete individual planets to see how much influence they had.
http://orbitsimulator.com/gravitySimulatorCloud/simulations/ssbarycenter.html
 
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Could play with that simulator for hours, maybe I’ll have some time tomorrow.
 

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