Pluto should be reclassified as a planet, experts say
The reason Pluto lost its planet status is not valid, according
to new research from the University of Central Florida in
Orlando. In 2006, the International Astronomical Union (IAU), a
global group of astronomy experts, established a definition of a
planet that required it to "clear" its orbit, or in other words, be the
largest gravitational force in its orbit. […]
Metzger, who is lead author on the study, reviewed scientific
literature from the past 200 years and found only one publication
-- from 1802 -- that used the clearing-orbit requirement to
classify planets, and it was based on since-disproven reasoning.
"It's a sloppy definition," Metzger said of the IAU's definition.
"They didn't say what they meant by clearing their orbit. If you
take that literally, then there are no planets, because no planet
clears its orbit." […]
Metzger said that the definition of a planet should be based
on its intrinsic properties, rather than ones that can change, such
as the dynamics of a planet's orbit. "Dynamics are not constant,
they are constantly changing," Metzger said. "So, they are not
the fundamental description of a body, they are just the
occupation of a body at a current era."
Instead, Metzger recommends classifying a planet based on
if it is large enough that its gravity allows it to become spherical
in shape. "And that's not just an arbitrary definition, Metzger
said. "It turns out this is an important milestone in the evolution
of a planetary body, because apparently when it happens, it
initiates active geology in the body."
Source: University of Central Florida. "Pluto should be reclassified as a planet, experts say."
ScienceDaily, 7 September 2018. Available at:<www.sciencedaily.com/releases/2018/09/180907110422.htm>.