Is it true that the denser planets are closer to the sun? Why?
Yes, the denser planets are closer to the Sun. Mercury, Venus, Earth, and Mars are the four densest planets of the 8 we now recognize. Density is defined as mass divided by volume. While all four of the gas giants (Jupiter, Saturn, Uranus, and Neptune) are more massive than the inner four, each is also surrounded by multi-thousand mile deep layers of gas which lower the overall density of the planets. The current theory is that the inner planets formed as the Sun was beginning to radiate. That early radiation/solar wind blew away any layers of hydrogen and helium that may have been collected by the larger bodies in the inner solar system, because they did not have the gravitational strength to hold on to it. As the Sun began to radiate and brighten, leftover gasses from the protoplanetary disk were blown outward. Thus the inner planets were basically balls of rock and iron with gravity too weak to create and hold the massive gas atmospheres we see on the outer planets. BUT, that does n
