Pluto is more alive than Mars, huff physicists who are still not over dwarf planet's demotion The drama surrounding Pluto’s planetary status just won’t die. A bunch of physicists are still fired up over the International Astronomical Union’s (IAU) decision to demote Pluto from being a fully fledged planet to a mere dwarf world in 2006. Pluto hovers on the edge of our Solar System, mixing it up with bits of icy debris …
"Since Pluto crosses Neptune's orbit presumably they will demote that as it hasn't cleared its neighbourhood"
Any definition of a planet is going to be arbitrary in some way or other. Personally, I'd be happy with a ten planet solar system with the substantive worlds of Pluto and Eris being upgraded to full planet status.
I'd draw the line for planet status at 10^22 kg mass to include Pluto and Eris but exclude all the significantly less massive bodies like Makemake, Haumea, Sedna, etc.
"I'd draw the line for planet status at 10^22 kg mass..."
More or less what the prof is proposing is 'enough mass that gravity pulls it into a spherical shape' without having to define the exact mass (the exact threshold of which might become a bone of contention).
Pluto's orbit is so far off the ecliptic plane, that it goes nowhere near Neptune's orbital path. It is correct, however, to say that it does approach the sun nearer than Neptune, because its orbit is so elliptical. This is in common with comets, as much as anything else.
The IAU needs to *FEEL* important, so they wielded power and demoted Pluto. I guess it was being a pain in 'Uranus' or something. So they're being like 'grammar nazis' (see icon) about it.
OBVIOUSLY way too much time on their hands... [are they being PAID for that?]
Io has formed itself into a sphere and appears to be the most geologically active "planet" in the Solar System with Titan not far behind. Be interesting to find out how many of the rereclassifiers consider Cruithne to be a moon of Earth...
Our Moon has also formed itself into a sphere, despite being largely inert. Io and Titan orbit Jupiter and Saturn. Cruithne orbits the Sun in a standard (albeit highly eccentric) elliptical orbit that happens to resonate with Earth's orbit in an interesting way.
Io and Titan are therefore Moons. Large and interesting moons to be sure. But moons nonetheless.
Cruithne cannot be considered a Moon of anything other than the Sun (which earns it an asteroid/Minor Planet designation).
University of Central Florida - much smarter boffins!
UCF's professors of astronomy might be smarter. My experience with the engineering interns of UCF and UF is that University of Florida students need less remedial training and hand holding to get started in the work place. UCF just seems to leave out little details in lab work, team work, and technical communications that UF addresses.
I do not get paid for an opinion. I get paid for my expertise in formulating an opinion which suits the party paying. And as those statements prove I can lie for free.
And allow me to introduce my assistant, Miss Nomer. Her opinion is that Earth is not a “planet” because it does not wander. The term derives, I think, from the Ancient Greeks, feet planted firmly on Plane... oops Ecosphere Earth from which vantage point all other components of the Solar System wandered across the sky and ergo were planets.
I'm sure that people stopped listing Ceres, Juno, Pallas, and Vesta among the planets of the solar system long before 1957. All asteroids are still also called by the name "minor planets", thus their orbits are listed in documents called the "minor planet circulars", but the Solar System had nine planets, not thirteen, after Pluto was discovered.
Pluto got demoted for the same basic reason as Ceres and company - there were too many others just about like it, starting with Eris. I'd prefer Pluto to stay a planet, but I really can't come up with a convincing argument against this brute fact. If planets aren't clearly bigger and more prominent than non-planets, the term loses its meaning, and if there are hundreds or thousands of planets, that's a useless situation too.
That's no excuse for having an ambiguous and sloppy definition just so one has a small list of planets for kids to learn.
How would you extend that definition on exo-planets? Say, in a solar system so young that none of its planets has yet cleared its orbit?
I'm fine with calling Pluto, Charon, Ceres, Juno, Pallas etc. planets. You can then further divide 'planets' into 'major' (our standard eight) and 'minor' (everything else).
Don't forget that Pluto was discovered by an American. Losing "planet" status meant loss of face.
Since it is about one sixth of the mass of the Moon and 0.2% of the earth, it's not a major planet. Labelling Pluto, Eris etc as minor or dwarf planets, or "plutoids" seems a fair compromise.
Before you "tell that to Jupiter", have a word with 884 Priamus, 624 Hektor and 3317 Paris and their opponents 1404 Ajax, 588 Achilles and 1647 Menelaus.
That said, I agree there's a difference between having camps of rocks at your Lagrange points and having NEPTUNE in your orbit. And while focusing on hydrostatic is interesting, plenty of moons are in hydrostatic equilibrium.
Go ahead, downvote me.
There you go, job's a good 'un.
If you reciprocate that will (at the time of writing) be my 9,999 downvote. After that, all I can say to other is be careful not to be trampled in the rush to bag the golden 10,000th downvote, which apparently confers a free lifetime subscription to the Register.
Go Pluto!! Seriously Pluto is a planet and it will remain a planet to all that love it. I'll say the IAU picked on the little guy cause they have size issues. Pluto is bigger than them all and some. I can smell the jealousy or someone was bored and want it to leave their mark as a planet killer. (not that I'm into constipated conspiracy theories but I found it strange the way they demoted our favorite small planet. ) : )
Real life is messy. Whatever definition you decide on is either gong to arbirarily chop pluto off the list or add some other bodies onto the list. Maybe harness the righteous anger and change the definition to include 'bodies humans live on' and see if the pissy people will start funding colonization programs for all their favorite former planets?
A bunch of physicists are still fired up over the International Astronomical Union’s (IAU) decision to demote Pluto
Pluto being a planet again seems to be an American preoccupation only, maybe because it was discovered by an American astronomer? Plutp's classification seems to be more a question of national pride than a physical consideration.
It would be a pity if the only thing the general public remembered about the New Horizons mission was that Pluto got reinstated as a planet because of it. I'd prefer them to remember it for the vast increase in our knowledge that it's brought about. Though obviously Pluto is a planet.
In my own opinion (and I'm not connected to the endeavour in any way whatsoever, so it is at least an honest opinion), New Horizons is way up there near the very top of accomplishments by the planet / moon / asteroid / comet botherers. To pull off such a info haul with a single opportunity was pretty spectacular. And there's more to come! Admittedly the top of that list is a crowded place to be placed in...
Here goes:
Mars class planets: things you can land on
Jupiter class planets: thing that are clearly planets but which you can't land on
Pluto class planets: things too small to be planets but look like planets and are fascinating in their own right
Earth class planets: things you can land on but wish you hadn't once you meet the inhabitants
Space debris: everything else
(Inspired by Miles Kington's "Nature made ridiculously simple")
I am still gutted by this declassification, I still remember the old phonetic for remember the planets, I have also taught this to my Son
My (Mercury) Very (Venus) Easy (Earth) Method (Mars) Just (Jupiter) Speeds (Saturn) Up (Uranus) Naming (Neptune) Planets (Pluto)
Doesn't work without good ole Pluto!
fast forward a few billion years
Sun reaching EOL and starts to expand, expansion destroys earth in suitably cataclysmic manner.
The inhabitants of Pluto are chatting
"There goes what they called the earth"
"Serves them right, not regarding us as a planet"
"Not that it matters, the muppets who slagged us off destroyed themselves long ago anyway"
"Still, it was a good light show"
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
