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Sing along if you know the word : When the Sun Myung Moon impinge on your eye , like a big pizza pie pie , that ’s a planet !
That ’s what ancient Greek stargazer call up , anyway . And according to a team of astronomers writing online Aug. 29 in thejournal Icarus , maybe it ’s time we take up thinking of Earth ’s trusty satellite — plus break gnome planets likePlutoandCeres — as a full - fledge planets once again .
Artist’s impression of Pluto and Charon as seen from one of Pluto’s other moons.
That might sound odd , but it ’s well within the consensus established by hundred of scientific literature , the new study reason . The source of that report scrub more than 200 years of scientific research to strain to reply two simple questions : What fix a planet , grant to the scientific biotic community ; and does that definition fall in line with the criteria that the International Astronomical Union ( IAU ) used in 2006 when they famouslystripped Pluto of its planethood ? [ Top 10 Amazing Moon Facts ]
The IAU ’s judging on Pluto ( and therefore all celestial body seek planethood ) does not talk for the scientific community , the author determined .
" There are 120 examples I found of scientist in the late put out literature assault the IAU definition , calling something a satellite even though the IAU definition says it ’s not a satellite , " lead study source Philip Metzger , a worldwide scientist at the University of Central Florida , differentiate NBCNews.com . " The reason erratic scientists do this is because the IAU definition is not utilitarian for science . "
What makes a planet?
After 76 years of text satellite status , Pluto was demote to a dwarf major planet in 2006when the IAU voted that the icy orb fail to meet a set of touchstone establish by decades of scientific literature .
To be a planet , they said , Pluto must : 1 ) Orbit the Sunday ; 2 ) Be massive enough to it pull out itself into a sphere shape under its own gravity ; 3 ) " Clear its neighbourhood " of debris and other celestial bodies , proving it has gravitational say-so in its corner of thesolar system of rules .
Pluto fails that third criterion . Because it orbits inthe Kuiper Belt — a monolithic ring of asteroids and minor planet that stretches beyond the ambit of Neptune — Pluto is circumvent by M of other celestial body and hunks of debris , each exerting its own gravity . Pluto , then , is not the gravitationally dominant physical object in its locality — and therefore , the IAU say , not a full - fledged planet .
harmonise to Metzger and his colleagues , however , that third routine of the touchstone is unnecessarily narrow — and not reflect in the consensus of preceding research . After looking at hundred of published astronomy papers going back to the 1800s , the researcher receive that , while most writers agreed that planet should be spherical and orbit the sun , the " clearing the neighborhood " rule appeared only in a single 1801 paper .
The researchers concluded that this Pluto - leave off linguistic rule is " arbitrary and not based on diachronic precedent , " and should be therefore snub when defining any present or future satellite - size object in our universe .
" WhenGalileo described the moons of Jupiter , he described them as planets , " study cobalt - author Kirby Runyon , a terrestrial geologist at the Johns Hopkins University Applied Physics Laboratory , tell NBCNews.com . " So , the actual historical case law is to consider pear-shaped worlds that revolve other planets as planets , too . And we see midget planets to be full - fledged major planet . "
By this revised standard Pluto is a satellite . So isEarth ’s moon , and the moons of Jupiter and Saturn . That ’s a controversial horizon that hasalready garnered some astro - criticism — and the study source are fine with that . If anyone disagrees with their appraisal , the researchers wrote , it should be up to the consensus of scientific literature to transfer it , not a right to vote by a single sanction like the IAU .
The study will be detailed in the February 2019 photographic print issue of Icarus .
earlier published onLive Science .
