Over a Hundred New Large Objects Found in the Kuiper Belt

UniverseToday ^

[DoodleBob]

They wouldn't survive the trip.

[Rocky]

From Wikipedia (for those like myself who don't know what a TNO is):

A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet or dwarf planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has a semi-major axis of 30.1 astronomical units (AU).

[Telepathic Intruder]

I agree that’s no moon, but it’s no planet either. Dwarf planet is a perfectly good description for a large asteroid or ball of ice that doesn’t have enough mass to dominate its own orbit. It was literally pushed out of the way by Neptune early in its history.

[DoodleBob]

doesn’t have enough mass to dominate its own orbit

...but it has enough mass to accumulate these guys...

...and if Alan Stern thinks it's a planet, then it's a planet. I like his explanation, which basically says the scientists were driven by memorization fear than science:

...Nowhere else in astronomy is there any definition that was specifically engineered to limit the number of objects to something that you can memorize... "when the world was quaint, and our knowledge was limited, and we only knew of 9 planets, you could know their names...then scientists...said 'this will tarnish our reputation, you know, school children won't be able to remember them...you know what I said? 'we're gonna go back to 8 states now?'...

Stern says "a planet is an object in space that's large enough to be rounded by its own self-gravity." That works for me.

[Telepathic Intruder]

In the end it's just a word, and word definitions change according to people's outlooks. Originally it meant something very specific: a star that wanders, not fixed in place like the rest. There were only 5 of them among the countless other stars, and the Earth wasn't even one of them. Then, starting with the telescope, our understanding of the universe grew. Planets were actually large bodies orbiting the sun, as was the Earth, having lost its imaginary place at the center of the universe.

As we found more and more objects in the solar system, the word 'planet' became more difficult to define. But there is a more esoteric meaning that has to do with Nebular theory of planet formation. Planets coalesce from a huge number of smaller planetesimals, each scooping out their own orbits from the random flying debris as they grow. At the end of the process you have large planets with their own individual orbits and no other objects threatening to replace them. This is how nature defines a planet. Objects such as asteroids and KBO's are formed in a different way.

So the question is, do we let the astrophysicists who understand the process define the terms, or the average person who just thinks it would be cool if Pluto is called a planet again? Or does it even matter at all?

[DoodleBob]

I’m just a dopey guy in FR. This issue is up to the experts, is DOES matter, and that was Stern’s point. He argues that the definition of a planet was altered to cap the number at 8. Stern argues that the definition should be true and if the number of planets grows to 27, then so be it. His analogy, about the Periodic Table, is compelling.

[SunkenCiv]

Missing socks wind up in the hoseone layer.

[SunkenCiv]

The demotion of Pluto was a political act by a supposedly scientific org, was a gratuitous and unnecessary action, carried out to belittle the US. IMHO of course. I'll stick with David Levy's view:

"To Pluto And Far Beyond" By David H. Levy, Parade, January 15, 2006 -- We don't have a dictionary definition yet that includes all the contingencies. In the wake of the new discovery, however, the International Astronomical Union has set up a group to develop a workable definition of planet. For our part, in consultation with several experienced planetary astronomers, Parade offers this definition: A planet is a body large enough that, when it formed, it condensed under its own gravity to be shaped like a sphere. It orbits a star directly and is not a moon of another planet.

[DoodleBob]

Thank you. That's what Alan Stern basically says as well. And that works for me.

If that IS what works, then how many known planets ARE in our solar system?

[SunkenCiv]

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[BraveMan]

The location of the newly found TNOs range from 30 to 90 AU . . .

Time to redraw the maps.