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Comment by shadowprofile77 | Hacker News Reader

Nitpicking, I know, but to call it "Planet Ceres" in the title is more than a bit wrong. This is a dwarf planet at best and is also often classified as a really big asteroid (the only one in the asteroid belt that's rounded by its own gravity). If even the much larger Pluto can't get the "Planet" title, Ceres hardly deserves to be called that in a headline from a major newspaper.

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I suppose the question is whether "dwarf" is a modifier to "planet" or whether "dwarf planet" is a compound word that cannot be split without losing meaning.

I would lean toward the former -- if there was not room in the headline for "Dwarf planet Ceres", referring to it as "Planet Ceres" still adds information and clarifies helpfully. "Ceres" may not be familiar enough to most readers for them to instantly think, "Oh, they must be talking about the largest asteroid/eighth largest known dwarf planet", but adding "planet" makes it clear that we're talking about space stuff.

Indeed, 'a dwarf something' is 'a something,' such as a 'dwarf star' or a 'dwarf tree.'

No, dwarf planet is a classification and NOT a modifier:

https://solarstory.net/planets/

EDIT: (Ceres) It is now considered as a "dwarf" planet, but is still labeled as an asteroid

Just an FYI, your link uses dwarf planet as a modifier.

From the Dwarf Planets section: "These planets are Pluto, Eris, Haumea, and Makemake."

(Not commenting on whether this is correct in this comment, just what the link says).

Ha! You got them :)

Here's a Euler diagram on planets, dwarf planets, minor planets, so on and so forth from Wikipedia [1].

Alan Stern, who coined the term "dwarf planet," initially wanted it to be under the umbrella of planet as a distinct subtype. [2]

The International Astronomical Union (IAU), however, believed that what we call a dwarf planet — it was referred to as a planetoid — should not be considered a type of planet.

The IAU later held a session where they decided to use the term dwarf planets in place of planetoids, however they decided that a dwarf planet is not a type of planet.

It's semantically inconsistent, but that's where we stand right now per the IAU.

[1] https://upload.wikimedia.org/wikipedia/commons/f/fc/Euler_di... [2] https://en.wikipedia.org/wiki/Dwarf_planet

I don't know what the criteria are for defining a planet (and I know that there is a great deal of controversy), but "rounded by its own gravity" seems like a good dividing line to me.

That is half of the criteria the IAU decided defined a planet. The problem is that our moon is rounded by its own gravity and would be classified as a planet under that just criterion.

The other half is meant to exclude moons from the 'planet' definition: the body must 'clear' the neighborhood around its orbit. The Earth is in the same solar orbit as our moon but is much more massive, thus our moon doesn't count as a planet. Pluto doesn't meet this criterion because its orbit intersects with Neptune's orbit, and Neptune is much more massive.

Funny enough the headline now reads "Dwarf planet Ceres ..."

>>If even the much larger Pluto can't get the "Planet" title

Damn you Neil deGrasse Tyson

Pluto is and always well be a planet

what an odd hill to die on...

Probably depends on your age. Did you grow up with Pluto being a planet? Having to learn about it in all levels of schooling as a planet? Seeing images of all the planets and Pluto is included?

Or did you grow up afterwards and learn from elementary school that Pluto is not a planet so people who still insist that Pluto is a planet seem anachronistic?

It would be like Hydrogen being removed from the periodic table and being told that from now on Hydrogen is no longer considered an element. Would you still try to say that you feel that Hydrogen really is an element, even though you are wrong and Hydrogen is not an element and never should have been included on the Periodic Table in the first place?

Pluto was a planet when I learned about it in school. I also learned that it was the one that was discovered last.

When they decided to change its status to dwarf planet, I looked up the reasons behind it, read up on the complexities of the matter, and could see the reasoning behind the change.

Then again, I hadn't reached thirty yet. Even in my forties I find it takes slightly more time to change my mind on some things...

> Did you grow up with Pluto being a planet? Having to learn about it in all levels of schooling as a planet? Seeing images of all the planets and Pluto is included?

Yup, grew up with all of those things.

And when they discovered more Plutoids - some even bigger than Pluto - when I was in high school, I loved watching science change as more information came in. Because that's what science does.

I love that we now have better definitions to more accurately describe bodies orbiting a star, and Pluto is definitely not a planet the same way the 8 planets are.

I see humor and sarcasm in 2020 is really dead...

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