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Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

theguardian.com

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Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#261

Post by [deleted] »

alehul wrote: post #259
saalweachter wrote: post #226

Earlier quoted context omitted.

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, "O…

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 la…

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Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#262

Post by [deleted] »

rovolo wrote: post #248
coolgeek wrote: post #235

Earlier quoted context omitted.

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…

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Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#263

Post by jayparth »

bjo590 wrote: post #44
jayparth wrote: post #41

Earlier quoted context omitted.

Well not necessarily. The Martian equator can get as hot as 18C. It doesn't retain the heat (due to no atmosphere) and it gets cold like even a few centimeters off of the surface.

Wow, I learned something new and can now think about the world more closely to how it really is. Thank you.

Your comment made me smile :)

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#264

Post by lopmotr »

KMag wrote: post #256
lopmotr wrote: post #255

Earlier quoted context omitted.

We have to assume something about the accuracy otherwise there might as well not be any numbers at all! What if it was +/- 100 K ? Writing 2 extra decimal places is assuming the original values also have 2 decimal places with zeros in them. It's reasonable to assume the digits the author gave are correct and there are no other unwritten zeros after them. Even if the scientists really did measure 110.00 - 155.00 K, th…

> Writing 2 extra decimal places is assuming the original values also have 2 decimal places with zeros in them. As long as you have at least one digit of precision, scientific notation is unambiguous as to the number of significant figures.

Yes, but these figures weren't written in scientific notation so we can't tell. Especially the trailing 0 on 110 is ambiguous because people often write a 0 there where it really is 0 while the convention is that a 0 means it's unknown.
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