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
In this solar system, Mercury and Venus have no moons. Mercury is the smallest planet in the solar system and only slightly larger than Earth's moon. It is the closest planet to the Sun. Venus is the second closest planet to the Sun and is slightly smaller than Earth.Full Answer >
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 >
One popular acronym for remembering the planets is "My very eager mother just served us nine pickles." Another popular acronym is "My very easy method just speeds up naming planets." These acronyms were created before Pluto was reclassified by the International Astronomical Union as a dwarf planet.Full Answer >
Various groups and people named the planets. The Romans named the five planets that are visible to the unaided eye: Mercury, Venus, Mars, Jupiter and Saturn. The names are based on the planets' appearances and movements. The Roman names were adopted by European languages and cultures, and they eventually became standard.Full Answer >