# Demoting Earth to non-planet status (along with Mars, Venus, Mercury and Pluto) **URL:** \ **Category:** Great Debates\ **Created:** [May 29, 2018, 3:15pm UTC](https://boards.straightdope.com/t/demoting-earth-to-non-planet-status-along-with-mars-venus-mercury-and-pluto/815062 "2018-05-29T15:15:43Z")\ **Posts on this page:** 1\ **Showing post:** 18
**Author:** ![Measure\_for\_Measure](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/measure_for_measure/32/557_2.png) [@Measure\_for\_Measure](https://boards.straightdope.com/u/Measure_for_Measure)\ **Post date:** [May 30, 2018, 5:56am UTC](https://boards.straightdope.com/t/demoting-earth-to-non-planet-status-along-with-mars-venus-mercury-and-pluto/815062/18 "2018-05-30T05:56:10Z")
Related if more whimsical 2015 thread: [What a planet is, revisited. Also Pluto](https://boards.straightdope.com/sdmb/showthread.php?t=762429), where I propose this definition, “A planet is a near-spherical object orbiting a star which has undergone planetary differentiation and is not a star or a brown dwarf.” Click the link to read informed objections and commentary, for I am not an astronomer. Also I posted: “ISTM that we’re defining a term inclusive of apples and hub caps while ruling out strawberries. Not that this is a huge issue: Phil Plait speaks for many when he asserts what matters are the properties of Pluto, not what label we stick to it. For this general interest message board though, it’s not a bad entry point to planetary science.” Lemur866 and more recently **Chronos** argue for the following: > [@Diversity of Solar System Bodies](https://boards.straightdope.com/t/diversity-of-solar-system-bodies/645836/5): > > There are three classes of objects in the solar system–rockballs, gasballs, and iceballs. --- _[View the full topic](https://boards.straightdope.com/t/demoting-earth-to-non-planet-status-along-with-mars-venus-mercury-and-pluto/815062)._