TransformerRobot Posted July 24, 2013 Share Posted July 24, 2013 Was there a time when the planets in our galaxy were closer to the sun than they are now? Link to comment Share on other sites More sharing options...
Ophiolite Posted July 24, 2013 Share Posted July 24, 2013 I think you mean, was there a time when the planets in our solar system were closer to the sun than now. The galaxy consists of billions of planetary systems, so very likley there have been times when some of them approached our sun more closely than is the case at present. In terms of the solar system, planets did a lot of moving around when the system was forming. Researchers seek to figure this out by running complex simulations. From what I recall it is likely that Jupiter moved in a little closer than it was, while Uranus and neptune may have swapped places. There was not, however, a general condition that all or most of the planets were at one time closer. I don't want to go into the effects of decrease in mass of the sun as a consequence of nuclear fusion. 2 Link to comment Share on other sites More sharing options...
dirtyamerica Posted July 24, 2013 Share Posted July 24, 2013 IIRC, Earth was closer to the sun about 8 months ago than now during its perihelion. 1 Link to comment Share on other sites More sharing options...
ACG52 Posted July 24, 2013 Share Posted July 24, 2013 Here's a simulation of the evolution of the outer gas giants. http://www.youtube.com/watch?v=6LzQfR-T5_A Link to comment Share on other sites More sharing options...
swansont Posted July 24, 2013 Share Posted July 24, 2013 IIRC, Earth was closer to the sun about 8 months ago than now during its perihelion. ~6.5 months. Perihelion was on January 2, aphelion on July 5 (using UTC). http://www.usno.navy.mil/USNO/astronomical-applications/data-services/earth-seasons Link to comment Share on other sites More sharing options...
TransformerRobot Posted July 24, 2013 Author Share Posted July 24, 2013 But I was wondering if maybe the planets were slowly drifting away from our sun. Link to comment Share on other sites More sharing options...
ACG52 Posted July 24, 2013 Share Posted July 24, 2013 Earth is slowly moving outward, due to the transfer of gravitational energy from the moon via the tides. Link to comment Share on other sites More sharing options...
TransformerRobot Posted July 25, 2013 Author Share Posted July 25, 2013 Earth is slowly moving outward, due to the transfer of gravitational energy from the moon via the tides. Is it the same case for Mars, Ceres and Jupiter? Link to comment Share on other sites More sharing options...
ACG52 Posted July 25, 2013 Share Posted July 25, 2013 Is it the same case for Mars, Ceres and Jupiter? No. What makes the earth-moon system unique is the relative size of the moon to the earth. Link to comment Share on other sites More sharing options...
swansont Posted July 25, 2013 Share Posted July 25, 2013 Earth is slowly moving outward, due to the transfer of gravitational energy from the moon via the tides. That is slowing our rotation, but not robbing us of orbital KE; for that to happen the interaction must come from outside the earth-moon system. Tidal braking with the sun should be occurring, as well as a tiny reduction in gravity from the sun from the conversion of mass into energy emitted in photons, and also a reduction in KE from our continued collection of dust and other particles. All small effects, AFAIK. No. What makes the earth-moon system unique is the relative size of the moon to the earth. Also the water, even though there are solid earth tides. The configuration of land vs ocean affects the efficiency of our tidal braking. 2 Link to comment Share on other sites More sharing options...
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