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Arthur T Knackerbracket has found the following story:
It turns out that Earth is not a planet. Asteroid 2016 H03, first spotted on April 27, 2016, by the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii, is a companion of Earth, too distant to be considered a true satellite.
"Since 2016 HO3 loops around our planet, but never ventures very far away as we both go around the sun, we refer to it as a quasi-satellite of Earth," said Paul Chodas, manager of NASA's Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California.
Asteroid 2016 H03 is proof that Earth has not cleared the neighborhood around its orbit. Therefore, under the definition of a planet vigorously defended by the IAU [International Astronomical Union] since the adoption of Resolution 5A on August 24, 2006, Earth is a 'dwarf planet' because it has not cleared its orbit, which is the only criteria of their definition that Pluto fails. (I think we'll eventually discover that very few of the 'planets' have cleared their orbits).
Most of us who were baffled by the IAUs declaration and outraged at the obvious discrimination of Pluto knew there was something wrong, even if we couldn't put our finger on it — we just 'knew' Pluto was a planet, right?
[...] Here's what all of us non-scientists intuitively understood all along: "A planet is defined as an astronomical body that "has not undergone nuclear fusion, and having sufficient self-gravitation to assume a spheroidal shape" — in other words, it's round and not on fire.
How could the distinguished scientists be so wrong?
-- submitted from IRC
(Score: 5, Insightful) by Immerman on Monday April 03 2017, @07:33PM (2 children)
Heck, forget Earth - Jupiter hasn't cleared it's orbit either, though I suppose the Lagrange Points get special consideration.
(Score: 4, Insightful) by julian on Monday April 03 2017, @09:24PM
Can we just abandon this futile attempt at platonic essentialism? Almost everything in the Universe is describable by its place on an n-fold continuum. There is no perfect form of "planetness" that real objects conform to more or less. Pluto is a rock/ice body with a certain mass, it has certain neighbors that share it's orbit or orbit around it. It has any number of characteristics that might be interesting to study. There are an infinite number of ways to prioritize these and weight them for assessing its membership in some category humans invented.
"Planet" is a label humans use because it is useful for the daily work of astronomy and planetary science. It's a good definition if it's useful. It's a bad definition if it causes more confusion than it dispels. Pluto will continue moving about its orbit just fine no matter what you call it.
So is Pluto a planet? It depends what you're interested in studying. A geologist might say yes. An astronomer might say no. We just have to be clear which definition we are using and why.
(Score: 0) by Anonymous Coward on Tuesday April 04 2017, @12:00AM
Lagrange points get the same "special consideration" as orbital resonances, such as the 1:1 resonance of "quasi-satellites" like 2016 HO3 with Earth, and 2:3 resonance like Pluto and the other plutinos have with Neptune.
Nobody serious denies that there's a useful distinction to be made between bodies such as Jupiter, which control a large region of space, and smaller bodies like asteroids and plutinos whose orbits are controlled by a nearby body in the first group, and the various criteria proposed to discriminate these classes of bodies are more in agreement than not, and all take such things into account. The disagreement is whether this classification, regarding a body's dynamical effects in relation to the rest of the solar system should be part of the definition of a planet, or whether planethood should be determined solely by properties of the body itself, and the dynamical classification should be another layer on top. (IAU tried to split the difference with "planet" and "dwarf planet", which is just a horrible naming convention.)