Planet size question?
Planets relatively close to the Sun (Mercury, Venus, Earth and Mars) are smaller than planets relatively far from the Sun (Jupiter, Saturn, Uranus and Neptune). Are there any reasons for this?
- skeptikLv 71 month agoFavorite Answer
The conventional hypothesis about it is that, as the proto-sun had mostly formed and started to radiate before the planets reached their final sizes, most of the lighter or more volatile materials (light gases and ices) were blown out past the "snow line" between Mars and Jupiter before planetary accretion ended. While the heavier rock and metal was able to remain where it was.
As there was much more of the lighter and more volatile material than there was of the denser material, the planets that are mostly composed of rock and metal (the "terrestrial" planets) ended up smaller than the ones that ended up with all the gas or ice.
- ANDYLv 51 month ago
A sure "reason" can not be expressed; only theories are present. For instance, scientists believe that Jupiter was once an inner planet between the Earth and Mars! And for some reason it got "kicked" away to its present location. Uranus, another example, has received an impact so violent its axial tilt has dropped to over 90°. Pluto, on the other hand, was our ninth planet (and still is for its name only has been changed). Pluto's orbital path around the sun is 17° inclined over the ecliptic plane. Theories to explain this abnormal angle vary, and one is it was "tossed" by a major body to that location.
So we can say that the present locations of the planets could also be related to circumstances occurring in the past billions of years.