This is a video explainer that describes why Pluto is no longer a planet. It talks about the history of Pluto and its discovery, and then the discovery of Eris, which is larger than Pluto. Now you can learn the official rules for planethood. Created by Christian Ready for Universe Today
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06Jan
Posted by Pluto @ 9:48 pm
Tags: astronomy, Eris, planets, Pluto, space, universetoday, why isn't pluto a planet
14 Responses
January 6th, 2012 at 9:48 pm
@christianready Right. Any two objects orbiting one another will have a barycenter somewhere, but Pluto and Charon orbit a location that’s above Pluto’s surface. For a while astronomers proposed that it made Pluto a binary planet.?
January 6th, 2012 at 9:48 pm
@illwing About the barycenter, I thought Pluto was unique in that its barycenter with Charon is outside of its surface. IIRC, only Pluto has this characteristic – all? other planets’ barycenters are well inside their host planets’ surfaces, no? Anyway, that was the point I was trying to make.
January 6th, 2012 at 9:48 pm
That’s messed? up.
January 6th, 2012 at 9:48 pm
NB: The Pluto-Charon+ system is not unique in orbiting a barycenter; our own Earth-Moon system does the same. More importantly, Pluto cohabits a narrow orbital “swath” with a very orderly class of KBOs called plutinos; these objects orbit the Sun in a stable resonance with Neptune’s orbit that prevents collisions/ejections over long time? scales. Only 141 plutinos have been discovered to date! Pluto is performing an intricate dance with Neptune, not haplessly plowing through a vast debris field.
January 6th, 2012 at 9:48 pm
It’s a piece called “Pendulum” which ships as part of Apple’s iLife? catalog of sound effects. Trying to keep it royalty free as I figure out how to do this 🙂
January 6th, 2012 at 9:48 pm
What’s the song that starts at 3:45??
January 6th, 2012 at 9:48 pm
Clyde Tombaugh must still be? turning in his grave…. 🙁
I will personally ALWAYS view Pluto as a planet…. 🙂
January 6th, 2012 at 9:48 pm
@laurele861, thanks for your comments. My intent was to discuss the history? of the findings that led up to the IAU’s decision, not to necessarily insist one way or another (though there is still debate as you point out.) You’re correct there are only relatively few KBOs as large as Pluto. I described the Kuiper Belt as consisting of over “70,000 large objects, each more than 100km across.” But that (to me anyway) wasn’t intended to imply most KBOs are Pluto-sized. Cheers.
January 6th, 2012 at 9:48 pm
It is disingenuous to present one side of an ongoing debate as fact when this is not the case. Many astronomers do still consider Pluto a planet. Eris has been found to be slightly smaller than Pluto, meaning the entire premise for the IAU vote was wrong. Also, there aren’t thousands of objects the size of Pluto and Eris in the Kuiper Belt; there may be as many as 50 or 100, among tens of? thousands of bodies. Those big enough to be squeezed into a round shape by their own gravity are planets.
January 6th, 2012 at 9:48 pm
Pluto IS still a planet. Only 4 percent of the IAU voted on this, and most are not? planetary scientists. Their decision was immediately opposed by hundreds of professional astronomers in a formal petition led by New Horizons Principal Investigator Dr. Alan Stern and like-minded scientists favor a broader planet definition that includes any non-self-luminous spheroidal body in orbit around a star. Dwarf planets are simply small planets not large enough to dominate their orbits.
January 6th, 2012 at 9:48 pm
Very nice, clear, concise? explanation. Thank you.
January 6th, 2012 at 9:48 pm
GREAT video, so good? and clear explanation!
January 6th, 2012 at 9:48 pm
3:57 “Fortunately Pluto is not forgotten.”
OH THANK GOD I WAS GETTING SO? WORRIED ;_;
January 6th, 2012 at 9:48 pm
It’s? more than 80 years – not 70.