Is the Earth falling into the sun from gravity?

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Discussion Overview

The discussion revolves around whether the Earth is getting closer to the Sun due to gravitational effects. Participants explore theoretical implications from general relativity (GR), the impact of gravitational waves, and the influence of the Sun's mass loss on Earth's orbit. The scope includes theoretical considerations and speculative reasoning regarding orbital dynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that the Earth is in free fall around the Sun but argue it is not, on average, getting closer to it.
  • According to general relativity, any planet orbiting a star emits gravitational waves, which theoretically could cause its orbit to decay over time; however, this effect is considered negligible for the Earth-Sun system.
  • One participant questions whether the Sun's mass loss from solar wind and radiation could counteract the effects of gravitational wave emission on Earth's orbit.
  • Another participant suggests that the Sun's mass loss would likely have a more significant impact than gravitational wave emission, although they have not performed the calculation to confirm this.
  • There is a mention of needing to consider accretion by both the Earth and the Sun in this context.

Areas of Agreement / Disagreement

Participants express differing views on the significance of gravitational waves versus the Sun's mass loss, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Participants acknowledge that the effects of gravitational waves are many orders of magnitude too small to matter in practical terms, and they highlight the importance of considering various factors like solar mass loss and accretion, which remain unresolved in the discussion.

BadgerBadger92
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TL;DR
Is the earth getting closer to the sun from gravity? Will we ever collide into the sun?
Is the Earth getting closer to the sun from gravity?
 
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The Earth is in free fall around the Sun thanks to gravity, but it is not, on average, getting closer to the Sun.
 
BadgerBadger92 said:
Is the Earth getting closer to the sun from gravity?
Theoretically, according to GR, any planet orbting a star should emit gravitational waves that will, after enough time has passed, cause its orbit to decay. However, for the Earth orbiting the Sun, this effect is many, many, many orders of magnitude too small to matter; lots of other things will happen (like the Sun turning into a red giant and probably becoming large enough to engulf the Earth) on time scales many, many, many orders of magnitude shorter than any orbital changes due to gravitational wave emission would even be detectable by our most sensitive instruments, let alone get large enough to bring the Earth significantly closer to the Sun.
 
PeterDonis said:
Theoretically, according to GR, any planet orbting a star should emit gravitational waves that will, after enough time has passed, cause its orbit to decay. However, for the Earth orbiting the Sun, this effect is many, many, many orders of magnitude too small to matter;
I wonder if the Sun's loss of mass via solar wind and radiation beats the effect of gravitational waves on Earth's orbit. Any idea?
 
Drakkith said:
I wonder if the Sun's loss of mass via solar wind and radiation beats the effect of gravitational waves on Earth's orbit. Any idea?
You'd need to consider accretion by both bodies, too.
 
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Drakkith said:
I wonder if the Sun's loss of mass via solar wind and radiation beats the effect of gravitational waves on Earth's orbit. Any idea?
I haven't done the calculation, but I would expect it to beat GW emission by many orders of magnitude. The GW emission rate for the Earth-Sun system as calculated by GR is really, really, really tiny.
 
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BadgerBadger92 said:
Summary:: Is the Earth getting closer to the sun from gravity? Will we ever collide into the sun?

Is the Earth getting closer to the sun from gravity?
What work have you already done to answer this? (It's okay...we all know the answer)
 
And, as usual, just another drive-by posting.
 
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