PDA

View Full Version : NASA New Horizons web site



Unregistered
2007-Jun-22, 01:36 PM
Saw this on NASAs New Horizons web site -

"What would a human see on Pluto?

An astronaut (Plutonaut?) stepping from their spaceship onto Pluto's surface would quickly notice many unusual qualities of this alien environment ... thousands of stars are visible, even in daytime." (Ref: http://pluto.jhuapl.edu/overview/faqs.php)

Is it just me, or is that, at least, incredibly misleading?

According to http://ask.metafilter.com/23197/Darkness-at-the-edge-of-town, "direct sunlight on Pluto is still a bit brighter than twilight on earth", which surely rules out seeing "thousands" of stars (unless, of course, you take precautions to hide the reflected light from the terrain (plutain?) entering your eyes). Pluto has the advantage of not having any atmosphere to speak of, but the adaptation of the eyes to the ambient light level must surely rule out seeing "thousands" of stars.

The other problem I see with that web site is their insistence on calling Pluto a planet -

"Pluto is the only planet in our solar system, unexplored by space probes".
"Pluto's gravity is weak so that it takes a large amount of fuel to go into orbit around the planet".
" ... making daytime on the distant planet much darker than a cloudy, stormy day here at home".
"Depending on which part of the planet the astronaut landed".
etc.

This is in spite of the fact that the site has evidently been updated since the redefinition of "planet".

tony873004
2007-Jun-22, 04:09 PM
I would tend to agree with you. The bright foreground, as well as the bright sun in the daytime sky would not allow your eyes to dark-adapt enough to see thousands of stars.

Maybe this was written before Pluto's demotion. But Nasa media gets things wrong sometimes. I was watching Nasa Educational Files on television and they said something like "This 98 kilogram backpack would only weigh 17 kilograms on the Moon."

baric
2007-Jun-25, 04:04 AM
I think Alan Stern is behind the persistent use of the term "planet". He's kind of been in a perpetual hissy fit about it since the IAU ruling, even though the ruling is very much in line with a paper he co-authored on the definition of planets a few years ago.

Just my opinion. He made some really unhinged comments after the ruling and insisted that he would defy the ruling and continue to use the term 'planet' in regards to Pluto.

EDG
2007-Jun-25, 04:33 AM
I think Alan Stern is behind the persistent use of the term "planet". He's kind of been in a perpetual hissy fit about it since the IAU ruling, even though the ruling is very much in line with a paper he co-authored on the definition of planets a few years ago.

Just my opinion. He made some really unhinged comments after the ruling and insisted that he would defy the ruling and continue to use the term 'planet' in regards to Pluto.

Yeah, I was involved in one of the arguments with him on one of the mailing lists we're both on :). It is odd, especially give that (as you note) what we ended up with isn't actually all that different to what he suggested previously.

parallaxicality
2007-Jun-25, 12:49 PM
Well to be fair, everyone and his brother's guilty of hyporcrisy on this. Even Mike Brown wavered a bit after discovering Eris. After all, would you want history to record you as the guy who discovered planet ten, or the guy who got Pluto demoted? Still, he came round to the IAU's decision in the end.

Ilya
2007-Jun-25, 05:30 PM
It is odd, especially give that (as you note) what we ended up with isn't actually all that different to what he suggested previously.

What did he suggest?

baric
2007-Jun-26, 04:36 AM
Well to be fair, everyone and his brother's guilty of hyporcrisy on this. Even Mike Brown wavered a bit after discovering Eris. After all, would you want history to record you as the guy who discovered planet ten, or the guy who got Pluto demoted? Still, he came round to the IAU's decision in the end.

Yes, and I was critical of Mike Brown in this forum for that. To his credit, he did come back around to his original opinion.

baric
2007-Jun-26, 04:38 AM
What did he suggest?

That the 8 classical planets are qualitatively different than Pluto and the other large bodies in the Solar System, precisely because they dominate their orbits. The conclusion of the paper was that it was sensible to have only 8 planets.

This was a few years before New Horizons, I think, so I guess his opinion changed.

parallaxicality
2007-Jun-27, 10:13 AM
Alan Stern may be acting petulent and hypocritical, but he did wager $700 million of taxpayers' money on a mission to the ninth planet. He has to keep the public on side somehow. Saying Pluto is just a KBO ain't gonna do that.

EDG
2007-Jun-27, 06:43 PM
Alan Stern may be acting petulent and hypocritical, but he did wager $700 million of taxpayers' money on a mission to the ninth planet.

There's no "wager" involved here - the probe's going to find interesting stuff regardless of whether Pluto is a proper planet or not. In fact it's already worth the money paid IMO just for the Jupiter flyby stuff (which as usual returned more info about Jupiter than Galileo ever did).

hhEb09'1
2007-Jun-27, 06:51 PM
Alan Stern may be acting petulent and hypocritical, Don't take baric's opinion for that
That the 8 classical planets are qualitatively different than Pluto and the other large bodies in the Solar System, precisely because they dominate their orbits. The conclusion of the paper was that it was sensible to have only 8 planets.

This was a few years before New Horizons, I think, so I guess his opinion changed.We had this discussion before (http://www.bautforum.com/showthread.php?p=814210#post814210), baric, and you didn't defend your position at the time. I think you're probably wrong.

PS:
Yeah, I was involved in one of the arguments with him on one of the mailing lists we're both on :). It is odd, especially give that (as you note) what we ended up with isn't actually all that different to what he suggested previously.OK, I missed this comment. Do you have some more info on that?

parallaxicality
2007-Jun-27, 08:54 PM
There's no "wager" involved here

There is if the probe breaks down. It's a lot easier to justify losing $700 million on a quest to the ninth planet than on a cruise to take snaps at a hunk of rock. If New Horizons doesn't make it, I doubt there will be another attempt.


OK, I missed this comment. Do you have some more info on that?

Here:

http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf

hhEb09'1
2007-Jun-27, 09:11 PM
Here:

http://www.boulder.swri.edu/~hal/PDF/planet_def.pdfI meant, in support of the contention by baric

baric
2007-Jun-28, 04:16 AM
Don't take baric's opinion for thatWe had this discussion before (http://www.bautforum.com/showthread.php?p=814210#post814210), baric, and you didn't defend your position at the time. I think you're probably wrong.

Didn't defend? I was involved heavily in that discussion for some time. After a while, you get tired of people arguing semantics and find something more constructive to do.

I have a tremendous respect for Alan Stern and what he has done for astronomy & planetary science. I am not going to rehash an old discussion about something I thought he was being inconsistent about at the time.

Everyone is free to read the paper he co-authored in 2000 and determine for themselves if Stern is making an case for 8 dominant planets in our system:
http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf

To imply that I somehow couldn't defend my statement because I didn't reply for the umpteenth time to a post at the end of yet another long discussion thread is unwarranted, imo. Stern's words in 2000 speak for themselves.

parallaxicality
2007-Jun-28, 07:20 AM
I meant, in support of the contention by baric

ex-squeeze me?


Hence, we define Uberplanet as a planetary body in orbit around a star that is dynamically important enough to have cleared its neighboring planetesimals in Hubble time.

baric
2007-Jun-28, 01:54 PM
Alan Stern may be acting petulent and hypocritical, but he did wager $700 million of taxpayers' money on a mission to the ninth planet. He has to keep the public on side somehow. Saying Pluto is just a KBO ain't gonna do that.

I do want to comment on this one aspect.. that I agree completely. If calling Pluto a 'planet' is the best way to continue public support & funding of space exploration, I am for it 100%. Stern's tireless efforts to make New Horizons a reality greatly overshadow, imo, his reactions to the IAU ruling.

However, the Ceres/Vesta mission is counter-evidence that a planetary body does not need to be officially designated a 'planet' in order to be explored.

hhEb09'1
2007-Jun-28, 05:32 PM
To imply that I somehow couldn't defend my statement because I didn't reply for the umpteenth time to a post at the end of yet another long discussion thread is unwarranted, imo.IMO, it is warranted.
Stern's words in 2000 speak for themselves.They seem to speak for themselves, but are you guys reading them?
ex-squeeze me?From that paper that you guys are linking to (http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf):

A planetary body is defined as any body in space that satisfies the following testable upper and lower bound criteria on its mass. If isolated from external perturbations, the body must:
1) Be low enough in mass that at no time (past or present) can it generate energy in its interior due to any self-sustaining nuclear fusion chain reaction. And also,
2) Be large enough that its shape becomes determined primarily by gravity rather than mechanical strength or other factors...Table 2. of the paper, near the last page, is "A Roster of Known Planets in Our Solar System By Type" and Pluto is included in the table, as is Jupiter and "Numerous KBOs".

I don't think you can use that paper to accuse Stern of hypocrisy. In fact, if that's all you got, I think you owe him an apology.

baric
2007-Jun-28, 07:51 PM
IMO, it is warranted.They seem to speak for themselves, but are you guys reading them?From that paper that you guys are linking to (http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf):
Table 2. of the paper, near the last page, is "A Roster of Known Planets in Our Solar System By Type" and Pluto is included in the table, as is Jupiter and "Numerous KBOs".

I don't think you can use that paper to accuse Stern of hypocrisy. In fact, if that's all you got, I think you owe him an apology.

Like most people, you continue to confuse labeling with classification. Stern proposes calling any gravitationally rounded object a 'planet', including moons, Ceres and large KBOs, and then refines that proposition by detailing a "Dynamical Classification Scheme". In that section, he makes it very clear that the 8 classical planets ("uber-planets") are qualitatively different then other planetary bodies in the Solar System ("unter-planets") based upon their ability to clear their orbits of other large bodies. He and Harold Levison describe what is fundamentally the underlying premise of the IAU decision that he now rejects. The only difference is cosmetic -- the particular labels applied to each category.

This discussion is fundamentally not about what is labeled a 'planet'. It is about whether Pluto and other large KBOs should be placed in the same category as the 8 classical planets. And yes, Stern SPECIFICALLY refers to Pluto as a KBO in that paper and I cannot believe I am still having to expound yet again upon this very elementary concept.

And get this... Stern refines his classfication even further, labeling Pluto and other similarly-sized bodies as "Subdwarf Planets"! In a sense, he "demotes" Pluto even more than the IAU!

As I said, I encourage anyone interested to read the Stern and Levison paper and decide for themselves.

EDG
2007-Jun-29, 12:00 AM
PS:OK, I missed this comment. Do you have some more info on that?

Not without posting the whole exchange - it was on the mailing list that Bruce Moomaw (one of the space journalists) set up. Everyone was discussing the IAU decisions, and Alan was very emphatic about not liking the final IAU decision and the way it was defined. I actually looked at his old paper (IIRC it mentioned "uberplanets" and "unterplanets", which stood out because I thought they were phenomenally unimaginative labels :)) and raised the fact that his proposal back then sounded similar to what was being suggested by the IAU and asked him why he'd apparently changed his mind. I don't recall what was said after that though, it was all pretty heated and heels were being dug in all over the place ;).

EDIT: Having a look at the emails again, it seems his beef was that he wanted objects to be classified based on their intrinsic properties only (i.e. not external, dynamical ones), and was upset that the IAU definition seemed to be a mix of both. in the Levinson-Stern paper, "unter" and "uber" planets are classes of planets, but he didn't like that the IAU definition because apparently those aren't subclasses of planets. The discussion fizzled out shortly thereafter, but while he was evidently quite convinced that he hadn't (at the very least) changed his mind over the years, it looked very much to me like he had changed it.

Sometimes scientists can be pretty emotional about the subjects they study - he's just as human as the rest of us ;). But I don't think he was doing his cause any favours by starting up petitions against the IAU decision. Most of us just reckoned that the IAU would refine the definition before their next big meeting - it's much better to work within the system than to declare it useless and try to start a revolution from outside. It just seemed like so much sour grapes to me, but either way I still respect the guy.

hhEb09'1
2007-Jun-29, 05:09 AM
This discussion is fundamentally not about what is labeled a 'planet'.As far as I am concerned, it is fundamentally about who is a hypocrite. Stern does not seem to be, and you have shown no evidence that he is. And yet you insist that you are right, and right to abandon the discussion.
, "unter" and "uber" planets are classes of planets, but he didn't like that the IAU definition because apparently those aren't subclasses of planets. The discussion fizzled out shortly thereafter, but while he was evidently quite convinced that he hadn't (at the very least) changed his mind over the years, it looked very much to me like he had changed it. Right, and on that basis of your opinion, you all are calling him a hypocrite. Amazing.

parallaxicality
2007-Jun-29, 05:12 AM
Hey I respect him too; I couldn't have got a Pluto mission off the ground, and so far it's been a spectacular success. He just doesn't wear Che's baret that well is all.

hhEb09'1
2007-Jun-29, 05:27 AM
To continually label someone a hypocrite, I would expect that there be some sort of evidence for the charge. People can change their minds, and I wouldn't necessarily label them a hypocrite for it. In my mind, a hypocrite is one who professes one thing, and does another, or something like that. But I don't even see any evidence yet where Sterns has changed his mind. I'll consider it when I get it.

Until then, I think you owe him an apology.

EDG
2007-Jun-29, 05:58 AM
Sorry, hhEb09'1 - are you some kind of Alan Stern fanboy or something? You seem to be taking this very personally given it's not even aimed at you. It seems to be that evidence has been presented and you're not accepting it - if that's the case then you're just going to keep saying he hasn't changed his mind when he has. And it's a waste of time to persuade you othrewise.

Maybe he's not a "hypocrite", but it seemed to me that he did a serious about-face between writing that paper and the IAU debate and then denied that he did. Maybe there's no conflict between what he said in the paper and what he says now in his own mind, but I still don't really understand how he justifies that.

And my opinion is based on a pretty lengthy email discussion with him. Have you talked to him much?

hhEb09'1
2007-Jun-29, 06:06 AM
Sorry, hhEb09'1 - are you some kind of Alan Stern fanboy or something? You seem to be taking this very personally given it's not even aimed at you. When someone labels someone a hypocrite, I want to see the evidence. When I waste a lot of time looking into it, and find out there is no evidence, I'm disappointed--and someone has wasted my time. So, yeah, I'm involved personally now.
Maybe he's not a "hypocrite",Evidentally.

but it seemed to me that he did a serious about-face between writing that paper and the IAU debate and then denied that he did.Nobody has showed me the evidence that he has. Where is it?
Maybe there's no conflict between what he said in the paper and what he says now in his own mind, but I still don't really understand how he justifies that. Well, I don't see the conflict either, so it appears to be in your mind. Labeling someone else a hypocrite just because you don't understand their position is...

Wait, I don't even understand why anyone would throw the term around in this discussion anyway. I should have known from the start that its use indicated a shoddy thought process.

EDG
2007-Jun-29, 06:28 AM
Really, if you're getting this riled up about some random person calling some other random person a hypocrite, then you're probably getting a bit too involved in things.

I'm telling you how a discussion - which you weren't part of (unless of course you are Alan Stern) - went and now you're telling me I'm wrong to think what I think. Well, I guess you're entitled to think that, but given you most likely weren't involved, who are you to tell me that?

And FWIW, what he said in the discussion is pretty much what he said at the time the IAU decision was announced so he's certainly not being hypocritical there.

It just looks to me like he changed his mind and did some pretty unconvincing footwork to claim that he actually hadn't. Last year he was extremely insistent that all planets should be defined by their own intrinsic properties and not on their orbital or dynamic properties or their location - but in th Stern-Levinson paper (http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf) he seemed quite happy to propose (on page 7) a "Lambda" term that is clearly a dynamical property, a measure of how well an object can clear out other bodies near its orbit. That's where he seems to have changed his mind.

hhEb09'1
2007-Jun-29, 07:25 AM
Really, if you're getting this riled up about some random person calling some other random person a hypocrite, then you're probably getting a bit too involved in things. Moi? :)

What rile?
I'm telling you how a discussion - which you weren't part of (unless of course you are Alan Stern) - went and now you're telling me I'm wrong to think what I think. Well, I guess you're entitled to think that, but given you most likely weren't involved, who are you to tell me that? I just wanted to see the evidence, that's all. Nobody has given me anything, except their personal opinion.

When baric said "The conclusion of the paper was that it was sensible to have only 8 planets," I expected to find that conclusion in the paper. It's not there.

I'm stating facts, not getting riled up.
It just looks to me like he changed his mind and did some pretty unconvincing footwork to claim that he actually hadn't. Last year he was extremely insistent that all planets should be defined by their own intrinsic properties and not on their orbital or dynamic properties or their location - but in th Stern-Levinson paper (http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf) he seemed quite happy to propose (on page 7) a "Lambda" term that is clearly a dynamical property, a measure of how well an object can clear out other bodies near its orbit. That's where he seems to have changed his mind.It looks to me like the paper discusses the dynamical property, but doesn't use it in the classification of "planet". As you say, that seems to be consistent with his position now. I don't see the hypocrisy that you all are talking about. I'm wondering what has riled you all.

EDG
2007-Jun-29, 08:09 AM
Moi? :)

Yes, toi. You're making a very big deal out of the fact that some people are saying that Alan Stern's opinion seems to have changed over the years.



I'm stating facts, not getting riled up.It looks to me like the paper discusses the dynamical property, but doesn't use it in the classification of "planet". As you say, that seems to be consistent with his position now. I don't see the hypocrisy that you all are talking about. I'm wondering what has riled you all.

I'm not riled. To be honest I don't really care what Alan Stern thinks of the matter now, because (as I suspected at the time) for all the fuss he made he didn't change anything, and the IAU definition still stands despite all the bluster and dismissiveness and revolutionary calls from his quarter. His camp noted their opinions very loudly, and that was that.

hhEb09'1
2007-Jun-29, 08:41 AM
Yes, toi. You're making a very big deal out of the fact that some people are saying that Alan Stern's opinion seems to have changed over the years. I'm just looking for some facts. The evidence I've been given doesn't support your contentions.

That's what we do here. :)

EDG
2007-Jun-29, 08:50 AM
The evidence I've been given doesn't support your contentions.

I'm sorry you can't see what others are seeing then. Like I said, you see what you want to see, and I disagree with you. If you want to keep making a big deal out of it then go ahead, but I'm not entirely sure why it's such a big concern of yours. :hand:

hhEb09'1
2007-Jun-29, 08:57 AM
I'm sorry you can't see what others are seeing then. Don't be sorry. :)

Do you think that "The conclusion of the paper was that it was sensible to have only 8 planets"?

baric
2007-Jun-29, 02:18 PM
OK, you seem to be so upset with my use of the term "hypocrite" with regards to Stern on this particular issue, so I've revisited my original thread on this to actually remember what we were arguing about:

Stern said this after the IAU decision:

"It's patently clear that Earth's zone is not cleared, Jupiter has 50,000 trojan asteroids," which orbit in lockstep with the planet.[

When the Stern-Levinson paper clearly said this:

we define an uber-planet as a planetary body in orbit around a star that is dynamically important enough to have cleared its neighboring planetesimals in a Hubble time

The paper goes on to categorize the 8 classical planets (but not Pluto) as uber-planets, and even includes a footnote to point out that the trojans are "locked into mean motion resonances with Jupiter". In other words, Stern clearly understands the concept of the "clearing the neighborhood" terminology used in the IAU decision -- even with respect to Trojans and Plutinos.

Here is my original complaint about Stern in the post you link:

And yet now Stern wants to assert that the glorified rocks in the various Lagrange zones of the 8 planets somehow disqualifies them from planethood, despite the fact that he is perfectly aware of the huge, qualitative difference involved.

And that is my beef with him. Not that he has changed his mind, but that he is feigning ignorance about the meaning of the IAU decision, demeaning the organization, its members and its process. It is petty, unprofessional and, given what we know he already knows, hypocritical.

Hypocrite: a person who professes beliefs and opinions that he does not hold

While I have a tremendous amount of respect for Stern and his contributions to planetary science and astronomy, he really diminished himself in the eyes of a lot of people with his bizarre reaction to the IAU decision.

hhEb09'1
2007-Jul-02, 04:42 PM
Thank you for the reasoned post baric, that's the sort of thing that keeps me here at BAUT.

However, I disagree. I can see where things might have been interpreted differently by the different parties.

It wasn't just the use of the word "hypocrite" that prompted me to press the issue. That usually means that someone (Stern in this case) is being accused of saying one thing and doing another--which I find rare in public forum, since the record is there for all to see. Unless the perp is of low morals--and no one seems to be accusing him of that. So, there's usually a story behind the story.

From my point of view, it looks like statements of Stern were interpreted, and when his actions didn't fall into line with that interpretation, some people were surprised. Clearly, there is an alternative interpretation--one that Stern himself seems to hold.

baric
2007-Jul-02, 06:45 PM
Clearly, there is an alternative interpretation--one that Stern himself seems to hold.

I, for one, would like to hear a reasonable interpretation on how Stern can assume contradictory positions to two statements with almost identical wording.

parallaxicality
2007-Jul-02, 07:37 PM
guys guys guys. Please. Let's not get too worked up over this.

As regards "hypocrite", I have a rule. Never post anything about someone else on an open forum you wouldn't want that person to read. In other words, don't use words about someone you wouldn't use to their face.

Alan Stern is a great guy. I can tell from his interviews. He's also managed to fulfil the childhood dreams of every geek on this forum and is taking a trip to Pluto. Even if that trip fails, he has a flawless Jupiter flyby to his credit.

Yes, his stance is perhaps a bit hypocritical. But this issue isn't just about science; it's about emotion, and in the realms of emotion things can get contradictory. I think, of all people, he probably deserves a little leeway to get emotionally involved. This matters to him.

hhEb09'1
2007-Jul-02, 08:12 PM
I, for one, would like to hear a reasonable interpretation on how Stern can assume contradictory positions to two statements with almost identical wording.I'll try, but I have to say up front, just to make it clear, that anything I say about his thought or motivation is speculative. And if I'm wrong, that's me being wrong not him. :)

The crux of the issue seems to be his lambda calculation, is that fair to say? He uses it to differentiate the eight major planets from the rest of the crew, in his paper, and you find that hard to reconcile with his current stance.

Is that a fair summary? or is there more that we should add?

baric
2007-Jul-02, 08:16 PM
As regards "hypocrite", I have a rule. Never post anything about someone else on an open forum you wouldn't want that person to read. In other words, don't use words about someone you wouldn't use to their face.

I agree completely. You might want to pass that advice on to Stern, as well, with regards to some very public and unflattering comments he has made about his peers.

Personally, I would have dropped this a while back if not for the inference that I was using "shoddy" logic and therefore could not defend my original statement. Do I not have a duty to respond to ad hominems like that? And as I have said before, I do not consider being called hypocritical about a particular position to be the grand slur that others make it out to be.

I am not going to flog this dead horse anymore. Anyone who wants to discuss with me further can do so through IM.

hhEb09'1
2007-Jul-02, 09:06 PM
The crux of the issue seems to be his lambda calculation, is that fair to say? He uses it to differentiate the eight major planets from the rest of the crew, in his paper, and you find that hard to reconcile with his current stance.OK, then, I'll start here.

The paper that is referenced (http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf) calculates a lambda, which depends upon many parameters. But the lambda calculation for a given planet does not depend upon how many bodies are in the planet's orbit. In other words, you could dump the entire asteroid belt into Jupiter's orbit, and that would not change Jupiter's lambda. So, I think it is unfair to characterize Stern's calculation of lambda as Stern saying that such and such a planet has cleared its orbit, especially when it seems Stern himself denies it.

dgavin
2007-Jul-11, 11:37 AM
To be hosest, as i'm of the 10 planet camp. I don't honestly don't mind the defination that led to demotion all that much.

They are still called Dwarf -Planets- after all.

I still think Belt Planet would have been a better term for them, as that implies they are part of simmilar group. And IMHO they should of left the Double Planet catagory in the definition they they had origionaly voted on.