Velocity of Earth Around Sun: Recent Claims & Calculations

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The discussion centers on the Earth's velocity in relation to its orbit around the Sun and its rotation, emphasizing that the speed of an orbiting planet is not constant due to Kepler's laws of motion. Recent claims indicate that the Earth's rotation is slowing down, primarily due to tidal friction with the Moon, which transfers energy and momentum from the Earth to the Moon, causing the latter to gradually move away. This tidal interaction results in a longer day on Earth over geological time scales. The conversation also touches on the complexities of orbital mechanics, clarifying that increasing an object's orbital speed can lead to a higher orbit, contrary to initial misconceptions. Overall, the dynamics of the Earth-Moon system illustrate the intricate relationship between rotation, tidal forces, and orbital mechanics.
  • #31
lazypast said:
im just curious, D H said something about the rate of radius increase to be the same as that of 1bn year ago.
I said nothing of the sort. :mad:

I said exactly the opposite:
D H said:
Actually, the slowing of the Earth's rotation rate has increased in the recent past (recent being relative to the 4.6 billion year age of the Earth).

What kind of evidence do we have of this? Fossil records indicate the Earth-Moon distance was 96.5% of its present value 620 million years ago. Averaged over that 620 million year period, this corresponds to a mean recession rate of about 2.2 cm/yr, which is considerably less than the current rate of 3.82±0.07 cm/yr. Records in the rocks take us back even further. The Earth-Moon distance was 90.6% of its present value 2.45 billion years ago. This corresponds to an even smaller recession rate of about 1.5 cm/yr on average for the last 2.45 billion years. We can go even further back in time. The rocks returned by the Apollo astronauts have been dated to 4.4 to 4.5 billion years old. The Moon has been around for a long, long time.

Bottom line: The current recession rate is anomalistically high.

References:
http://adsabs.harvard.edu/abs/2000RvGeo..38...37W
http://pubs.usgs.gov/gip/geotime/age.html
 
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  • #32
How will global warming affect the recession rate? Due to sea level rise, the length of the coast lines that are involved in pushing the tidal bulges forward will change a bit...
 
  • #33
global warming would not have a significant effect on recession rate,since that
in terms of rise in sea level is very gradual .but my doubt is
we cannot determine Earth's speed simply by doing velocity by time,taking time as 365 days and circumference of ellipse ,since we are finding angular velocity(omega)?
 

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