Pluto , the glacial underdog of the Solar System , was “ relegate ” from a planet to a dwarf planet by the International Astronomical Union ( IAU ) in 2006 , after they contestedpoor honest-to-goodness Plutodidn’t fit out their raw criteria for a true planet . Ever since the controversial conclusion , Pluto ’s legion of loyal fans and many astrophysicists have been fight back against the conclusion .
Alan Stern and David Grinspoon – master investigator of the New Horizons commission to Pluto and astrobiologist , respectively – have written an article for theWashington Postthat set frontwards their showcase to " Make Pluto Great Again " ( or at least a true planet again ) .
The 2006 IAU definitionrequires a heavenly soundbox to tick three boxes before it can be scream a satellite . First up , it must be in orbit around the Sun . Secondly , it must have sufficient self - gravity to make a unit of ammunition ( or nearly round ) shape . Finally , it has to have cleared the neighborhood around its ambit . Since Pluto is environ with a swarm of other icy Kuiper Belt object like to itself , itdoes not fitwith the definition and is therefore not a true satellite , they indicate .
Stern and Grinspoon write that the definition was " hurriedly drawn " and contain " obvious flaw " . After all , it would mean that Earth is not a major planet because it has many asteroids in its region that have not been cleared out . moreover , the definition fails to consider exoplanets , the innumerable planet that live beyond our own Solar System . The more of these exoplanets we distinguish , the more this definition appear needlessly stiff .
alternatively , they argue the term " satellite " should be used to draw worlds with intrinsic geophysical property , not merely orbital properties .
“ We apply ' planet ' to describe worlds with certain quality , ” explicate Stern and Grinspoon . “ When we see one like Pluto , with its many intimate features – mountains of chicken feed , glaciers of nitrogen , a drear sky with layers of smog – we and our colleagues quite naturally chance ourselves using the word ' major planet ' to account it and compare it to other planets that we know and love . ”
The debate has since send away up on Twitter too , as most arguments tend to do :
Speaking toIFLSciencelast yr , Alan Stern further bear on this point , mention : “ [ The IAU is ] primarily made up of non - experts , astronomers who study opprobrious hole and Galax urceolata . Other organisation [ with planetary scientists ] may be more appropriate . ”
Instead , Stern and Grinspoon citeanother definitionput forward in 2017 at the yearly Lunar and Planetary Science Conference : " Round objects in space that are smaller than mavin . “Of course , not all astronomers are convince by this contention either , as that would intend most Moons in the Solar System would also be considered planets . EvenCosmoshost Neil deGrasse Tyson haspreviously arguedonThe Late Show with Stephen Colbertthat Pluto is not a satellite . After mention that Pluto ’s compass occasionally crosses Neptune , he shouted : " That ’s no kind of behavior for a planet . No ! "
One affair is more certain , the argument around Pluto ’s planethood is far from dead .
