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The story
According to a CNN report from October 29, astronomers have discovered an object orbiting beyond Pluto’s orbit, provisionally named “ED138.” It’s estimated to be roughly 600-1,500 km in diameter and could potentially become a recognized dwarf planet. On 5ch, while many posters explained that this is a separate object from the undiscovered “Planet Nine” (believed to be about 10 times Earth’s mass), the more common reaction was a cool-headed “We don’t get what’s supposed to be surprising — there are already several dwarf planets beyond Pluto, like Eris, Makemake, and Haumea,” with many questioning whether the news was even novel.
Published 10/29 (Thu) 14:00
CNN.co.jp
(CNN) — Astronomers have discovered an object within the solar system that may be a new dwarf planet. Orbiting beyond Pluto’s orbit, the object has been provisionally named “ED138.”
Source: news.yahoo.co.jp / Original article here
What people said
> ED138 is estimated to be 600-1,500 km in diameter.
Okay, thread's over, everybody go home!
This new dwarf planet candidate is only about 600-1,500 km across, not massive enough to affect other objects' orbits
(it was found purely through optical observation).
Planet Nine, on the other hand, is said to be about 10 times Earth's mass.
Expect a lot more of these to turn up.
So it's Planet Kororin!
If it really exists and isn't some unusually weird object, optical observation should be possible.
We have space telescopes now, so it should be clearly visible.
They should've confirmed it before writing the article.
Actually, no — apparently it was found as a moving point of light across multiple photos of the sky.
Its position is already known now, so anyone can observe it.
It's tilted quite far from the solar system's ecliptic plane, and it probably doesn't have enough mass to affect other bodies.
Eris, Makemake, and Haumea are ALL already dwarf planets beyond Pluto. What is this dumb news story???
Because they discovered a new dwarf planet.
> One of the conditions for being classified a planet is that it has gravitationally swept its orbital neighborhood clear of other bodies.
That definition was set 20 years ago, but it's way too outdated now that we've discovered so many exoplanets.
That's because we now know planetary orbits aren't static the way they used to be imagined — they shift dynamically over time.
Our solar system, neatly arranged with the heaviest planet (Jupiter) at the center and mass tapering off both inward and outward, turns out to be the exception rather than the typical case.
Exactly, so this doesn't really have much news value.
Turns out a lot of them orbit on paths that have nothing to do with the ecliptic plane, which has made them hard to find.
If there were an object with an extremely elongated elliptical orbit and an orbital period of a billion or even ten billion years around the sun, it's questionable whether we could even recognize it as a member of the solar system. And if it picked up energy from somewhere, its elliptical orbit could turn into a parabolic one and it could fly off, never to return — but even if that happened, would it still count as part of the solar system? (Kind of like an older brother who ran away from home.)
There's also the gravity of nearby stars to factor in, so I doubt a stable orbit lasting hundreds of millions of years is even possible, right?
"Hey now, I even appeared in Space Battleship Yamato! There's even an anime where the main character shares my name (Pluto)!
So why the heck did I get kicked out of the solar system's planets? At least make me an 'honorary planet,' come on!
You stubborn blockheads at the astronomical society!"
Background and Key Points of This Discussion
Under the International Astronomical Union’s (IAU) 2006 redefinition, Pluto was demoted to dwarf planet status for “not having gravitationally cleared other bodies from its orbital neighborhood.” Since then, objects in the same class — Eris, Makemake, Haumea, and others — have been found one after another, and the thread reflected that history: plenty of posters pointed out that there are already plenty of dwarf planets beyond Pluto, with a cool reaction that this new ED138 find is just more of the same and not especially surprising. That said, it is clearly distinct from the undiscovered “Planet Nine,” believed to be roughly 10 times Earth’s mass — and unlike a mass-based inference, ED138, a small body estimated at 600-1,500 km across, was directly observed as a moving point of light across multiple photographs. Its existence wasn’t inferred from gravitational effects on other bodies, and its position has already been pinned down, so the criticism that “this is just an estimate, not a real discovery” doesn’t strictly hold up. The thread’s core debate ended up being a mix of misunderstandings about how dwarf planets are defined and what counts as a “discovery.”
*This article is excerpted and summarized from the 5ch (Science News+) thread “[Space] Astronomers Make Surprising Discovery, Possible New Dwarf Planet Beyond Pluto.”
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