Speed of earth around the sun

Juswannaknow

I understand that the earth takes 365 days (give or take) to orbit the sun. I also understand that the physics of the universe are in continual flux (expanding universe, cooling suns, etc).

Question: Is it plausible to assume that the earth took a shorter/longer time to orbit the sun a billion (5 billion, 10 billion) years ago? If so, is there any studies or evidence indicating the rate of change?

mathman

With a little help from google I got:

------------------------------------------------------------------------------------
After the formation of the solar system (-4.5 Byr) the Earth orbit was at 1.38E08 km (presently 1.50E08 km) and the Earth period was 0.89 years. In the future (+4.5Byr), they are predicted to be 1.64E08 km and 1.15 yr. At -4.5 Byr, present temperatures of -50, zero, and + 50 C were higher at -40.5, 11.7, and 63.9 C, respectively. It is predicted that in +4.5 Byr, these temperatures will have decreased to -60.0, -12.2, and 35.5 C. In the past million years, the present -50, 0, and +50 C temperatures were about 0.03C higher, and will be about 0.03 C lower in another million years. These results indicate that temperature changes due to solar-Earth orbital interactions do not significantly contribute to the observed Earth global warming observations.

Above is from:

American Geophysical Union - 2007 Fall Meeting
Earth Orbit, Period, and Temperature - Past and Future
(Abstract)

Presentation:
10–14 December 2007
Ingo H. Leubner Rochester
Institute for fundamental Research

DaveC426913

So, causes of change in Earth-Sun distance:

- expanding universe: no
- tidal braking: yes

physixlover

Trying to find about what actuallty tidal braking was i found an explanation to the one
http://athene.as.arizona.edu/~lclose...202/lect6.html

Juswannaknow

Hmmm.. thank you very much! I had the impression that the changes would be much greater.