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Comment by jobu | Hacker News Reader

“Saturn has a hexagon at the north pole,” said Bolton. “There is nothing on Jupiter that anywhere near resembles that. The largest planet in our solar system is truly unique. We have 36 more flybys to study just how unique it really is.”

This is the first I've heard of Saturn's hexagon, very interesting: http://www.space.com/30608-mysterious-saturn-hexagon-explain...

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Some threads I read on another site described it as perturbations of a periodic wave moving around the pole in a circle.. modeled something like this:

http://www.wolframalpha.com/input/?i=plot+x%5E2+%2B+y%5E2+%3...) or http://www.wolframalpha.com/input/?i=r+%3D+1+%2B+cos(6*theta...

Doesn't seem to hold up to a sensitivity analysis as much as one would expect given how long it has remained stable.

Does Saturn have an identical cloud pattern on its south pole? I always hear about the north pole, but without geographic features wouldn't there be symmetry between the north and south poles?

Not quite, but there's definitely something strange there.

http://apod.nasa.gov/apod/ap081027.html

"This is the first I've heard of Saturn's hexagon, very interesting"

Yes, me too -- thanks for posting your reply and the link, I've now learnt something new today (and it's only 00:45 so that's a good start to the weekend!).

>The largest planet in our solar system is truly unique.

Hold on -- how much do we know about the poles of gas giants in other solar systems? I'm guessing we can't get a good look or anything...

Edit: added quote to clarify what I was responding to.

Saturn has a tilt just a bit more than the Earth and it experiences seasons; the pole is rotated something like 26 degrees into our field of vision in "winter". Uranus is actually rotating on it's side.

http://www.setterfield.org/Astronomy/pictures/axial-tilt-pla...

"other solar systems"

The answer is we don't. Unlike the other three gas giants in the Solar System we can't see Jupiter's pole clearly. So Jupiter is unique to our solar system, and we don't know much about the visual details of exoplanets.

Is Jupiter all gas or does it have any mass? It is hard for m kind to imagine a big ball of gas looking like a planet and going around the sun

The thing is, there's a lot of gas, which like any other matter, has mass. So, even though a hydrogen atom is the lightest element possible, and we think of hydrogen gas a being light, that's just relative to other things. At a human scale, it isn't possible to have that much of the stuff around. But you can always go and collect a lot of it; in fact if you get ten to the power twenty seven kilograms of the stuff, and put it in one place, gravity will shape it into a sphere that looks very like Jupiter. Or, get 1000 times as much as that, and watch as gravity squeezes it so much it begins to fuse into helium at the centre - you'll have a star the size of our Sun...!

Jupiter is almost all hydrogen. However, the bulk of that hydrogen is actually liquid. Its core has compressed the hydrogen so much that it's ionized and is essentially a metal.

We know basically nothing about the details of cloud structure on exoplanets.

Then it's kind of a stretch to call Jupiter "truly unique" in this respect, isn't it? "Wow, only a quarter of known gas giants are like this!"

It's an interesting story with an awkward headline and opening quote. The word "unique" is being pressed into duty as a terse synonym for "interesting in all sorts of ways that will require you to read entire paragraphs of information to understand."

I'm inclined to forgive NASA on this one. The accuracy/brevity trade-off tortures anyone who tries to popularize science.

Yes. What's the point you're trying to make? (genuine question)

To express skepticism about

>The largest planet in our solar system is truly unique.

It's unique within our solar system, the only one we have details about. I think it's fair to state that as being unique. The implication (that we don't know about other solar systems) doesn't need to be stated, at least to me.

Since we're in the business of nitpicking – unique means one of a kind, so the "truly" is redundant. That said, there are so many planets in the Universe that it's practically impossible for any single one to be unique – the term is being used here not in a technically accurate way, but in a loose, "I want you to be impressed" sense.

Well, if you think about it, there aren't two planets which are 100% alike, so each planet can be called unique.

That's true, but in which case the term ceases to be useful!

How about, "Truly unique in our experience?"

It's a common use of the word "unique".

The usage has deviated from the original meaning. Making a big deal out of it doesn't make you look smart; it makes you look out of touch.

I am unfamiliar with unique meaning anything but "one of a kind", mind educating me?

Another definition of unique is "particularly remarkable, special, or unusual" [1].

Makes sense with how the original quote also said "We have 36 more flybys to study just how unique it really is."

www.merriam-webster.com has one definition which says it's a synonym of "unusual" [2].

[1] https://www.google.com/#q=unique (in the top info box)

[2] http://www.merriam-webster.com/dictionary/unique (#3 in the full definition, all-caps meaning that it's a synonym for the word in caps)

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