3 ms·

To add to your fun fact: the reason that most of the planets spin in the same direction is that the solar system formed from a single giant rotating disc of roc

• btilly 13y ago
  And the stuff that happened to randomly go against the flow generally gets pulled into lockstep with the rest by tidal forces. But not entirely - the amount of axial tilt turns out to be a chaotic system. About 20 years ago I ran across an estimate that if the Earth did not have the Moon, then every so often we would randomly wind up with a sufficient tilt to be extremely difficult for life. Therefore our Moon may have been critical for sustaining life as we know it. See http://www.nytimes.com/1993/03/02/science/moon-may-save-earth-from-chaotic-tilting-of-other-planets.html?pagewanted=all&src=pm http://www.nytimes.com/1993/03/02/science/moon-may-save-eart... for confirmation of that tidbit.
  • ra 13y ago
    To add to that, the reason that the tilt is so important for life on Earth, is because the tilt causes the seasons. The seasonal variation of warmth from the sun leads to differences in atmospheric and surface temperatures. The atmosphere warms faster than the oceans, creating a temperature gradient. This is the primarily mechanism that energises the water cycle. i.e. evaporation, cloud formation, rain, rivers etc.