The goal of comparative planetology is to discover the commonalities among the ways that planets form and evolve. The planets that have been discovered differ substantially from one another when viewed as individual, isolated systems, but astronomers believe that there are universal principles that apply to them. By comparing the properties of different planets, scientists hope to spot these universal principles and gain greater insights.Know More
There are many factors that separate each planet in Earth's solar system from one another, and that is only within one solar system. Scientists have discovered many planets orbiting other stars, some quite different from the ones near Earth. The biggest division in comparative planetology is between the rocky planets, like Mercury, Venus, Earth and Mars, and the gas giants, Jupiter, Saturn, Uranus and Neptune. In comparative planetology, scientists look for commonalities both within and between these major groups.
Even within this solar system, comparative planetology is in its infancy. The ability to send probes beneath the outer atmospheres of other planets is relatively new and still extremely limited. Even relatively close planets with known solid surfaces, like Venus, contain conditions that are incredibly hostile to most equipment. Even worse are the gas giants, with their immense gravity, thick atmospheres and extreme weather.Learn more about Planets
Planets shine because they reflect sunlight. Unlike stars, planets do not produce their own natural light. Their close proximity to Earth allows them to reflect enough sunlight to make many of them visible in the night sky.Full Answer >
As of 2014, there are eight planets in Earth's solar system. In order by distance to the sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto was considered to be a ninth planet until 2006, when it was demoted to a dwarf planet.Full Answer >
The names of the inner, or terrestrial, planets are Mercury, Venus, Earth and Mars. The outer planets are Jupiter, Saturn, Uranus and Neptune. Pluto was once designated a planet but has now been demoted to a dwarf planet.Full Answer >
The nine planets in this solar system somewhat align once every 500 years and are grouped within 30 degrees every one to three alignments. When astrologers describe the planets as being aligned, they do not necessarily mean that all of the planets line up on a perfectly straight line. The last alignment within 30 degrees occurred in 561 B.C., and the next alignment within 30 degrees takes place in 2854.Full Answer >