Earth's position relative to the Sun.

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Discussion Overview

The discussion revolves around the Earth's position relative to the Sun, particularly in the context of the Sun's transition into its Red Giant phase. Participants explore the implications of gravitational attraction and the effects of the Sun's mass loss on Earth's orbit.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that the Earth's position is influenced by gravitational attraction and questions if the Earth will be pushed into Mars's orbital path when the Sun becomes a Red Giant.
  • Another participant argues that the expansion of the Sun will not significantly affect Earth's orbit, emphasizing that gravitational force depends on mass rather than size.
  • It is proposed that as the Sun expands, the gravitational attraction will increase due to decreasing distance, leading to the possibility of the Earth being engulfed by the Sun.
  • Some participants clarify that gravitational force is a function of distance to the Sun's center of mass and that the Sun's mass is decreasing, which may cause the Earth to spiral outward slightly, although this change is described as small.
  • There is a mention that the Sun will shed mass during its transition to a Red Giant, which could result in an increase in Earth's orbital radius.

Areas of Agreement / Disagreement

Participants express differing views on the effects of the Sun's expansion and mass loss on Earth's orbit. There is no consensus on whether the Earth will be engulfed by the Sun or if it will spiral outward due to mass loss.

Contextual Notes

Discussions include assumptions about gravitational forces, the impact of the Sun's size versus mass, and the implications of mass loss during the Sun's evolution. These factors remain unresolved and are subject to interpretation.

Khan Wolf
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Would someone please correct my train of thought on this?

I understood that the Earth's position in the Solar System is related to the gravitational attraction between the Earth and the Sun. If this thought is correct, then when the Sun enters its Red Giant phase, the Earth should be pushed back into Mars's orbital path. Thoughts...corrections...help!
 
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HI Khan Wolf! :smile:
Khan Wolf said:
… the Earth's position in the Solar System is related to the gravitational attraction between the Earth and the Sun. If this thought is correct, then when the Sun enters its Red Giant phase, the Earth should be pushed back into Mars's orbital path.

No, the expansion of the Sun will make almost no difference to the Earth's orbit …

once you get into "empty space", the gravitational field of a star depends on its mass, not on its size. :wink:
 
When the Sun enters its Red Giant phase, the Earth should be pushed back into Mars's orbital path

The distance between the Earth and Sun will become less and less so the gravitationional attraction will become greater and greater. The Earth would therefore be engulfed by the Sun.
 
Philosophaie said:
The distance between the Earth and Sun will become less and less so the gravitationional attraction will become greater and greater. The Earth would therefore be engulfed by the Sun.
Gravitational force is pretty much a function of distance to the Sun's center of mass, not its surface. Assuming the Sun's mass doesn't change, the gravitational attraction between the Sun and the Earth will be pretty much the same whether the Sun is a red giant whose radius is just shy of 1 AU or a tiny white dwarf.

However, the Sun's mass is not constant. It is losing mass due to fusion in the Sun's core and solar wind from the Sun's surface. The Earth will (and is) spiral out a bit from the Sun. The change is rather small, however, and most likely will not save the Earth from being engulfed when the Sun enters its red giant phase.
 
tiny-tim said:
HI Khan Wolf! :smile:


No, the expansion of the Sun will make almost no difference to the Earth's orbit …

once you get into "empty space", the gravitational field of a star depends on its mass, not on its size. :wink:

While this is of course true, when the Sun enters its red giant phase not just expansion takes place! Realistically, the sun will begin to shed an appreciable portion of its mass, both during the transition and once it becomes a red giant due to increased stellar winds. So the net effect of the sun moving off the main sequence is an increase in orbital radius.
 

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