The Sun's 10th Planet... Sedna?

dsanfte writes "While NASA remains intentionally vague, promising only a news conference Monday, The Australian has the details. The new planet, dubbed Sedna after the Inuit goddess of the sea, is 3 billion km further from the sun than Pluto, and is slightly smaller at 2000km in diameter. This discovery has apparently reignited the debate as to how big a solar object must be in order to qualify as a 'planet', but it is significant nonetheless."

A lot of astronomers don't want to count Pluto

So why should we start counting an even smaller "planet"? Pluto gets grandfathered in, and that's it.

Re:A lot of astronomers don't want to count Pluto

You exclusive club-types are all alike....

Here, a rule that I propose.. planet versus other:

If it's big enough to assume spherical shape by the action of gravity, it's a planet.

Re:Here, a rule that I propose.. planet versus oth

By that logic, Anna Nicole Smith qualifies. ;)

Re:A lot of astronomers don't want to count Pluto

I say we put up a huge sign next to the Sun that says "You must be at least this big (insert huge red line) to ride this ride."

Re:A lot of astronomers don't want to count Pluto

So where's the line between asteroid [wikipedia.org] and planet [wikipedia.org]? IMO, Pluto [wikipedia.org] should be labeled an asteroid since it's smaller than even our own moon [wikipedia.org]. Of course, there are also asteroids with moons but yet, they are considered asteroids, not planets. And what makes a comet [wikipedia.org] a comet and not an asteroid, it's orbit? It would certailny seem that agencies like NASA that are so concerned with being precise in other areas could could come up with a more precise classification system.

Re:A lot of astronomers don't want to count Pluto

Comets are snowballs; asteroids are rocks. Oversimplification, but you get the idea.

Re:A lot of astronomers don't want to count Pluto

"asteroids are rocks"

We should use this for the demarkation between "asteroid" and "planet." An asteroid is one big chunk of rock. A planet is a bunch of little rocks held together by their own gravity.

If Pluto primarily orbits the sun and it's dense enough to hold on to an atmosphere from time to time, why shouldn't it be considered a planet?

Re:A lot of astronomers don't want to count Pluto

A large number of known asteroids are exactly that: clumps of rock weakly held together through their own weak gravitational forces.

This incidentally leads to one of the fears of trying to deflect such an asteroid were it on a collision with the earth -- that it would simply fragment it and cause destruction on a wider scale.

Re:A lot of astronomers don't want to count Pluto

I'd prefer that. In an extreme situation, where the object would be fragmented to a bunch of dust & powder, everything would get burned up in the atmosphere. I could be wrong, but that's where I'm placing my bets.

From Phil Plait's Bad Astronomy: Review of Deep Impact [badastronomy.com]:

This was the Biggest Baddest Astronomy in the movie. Blowing up a comet does no good at all, and might even make matters worse. Just because the pieces are smaller doesn't mean you have changed anything. If every piece still impacts the Earth (by that I mean actually is stopped by the Earth or its atmosphere) you are still dumping all the kinetic energy of The Comet into the Earth's atmosphere! That's a HUGE amount of energy, dumped in practically all at once. It would still create a massive explosion, dwarfing all of our nuclear bombs combined. Even if you could somehow soften the blow, all that heat would wreak havoc with our weather. Some people actually think it might be better to simply let a big one hit rather than blow it up, because the Earth itself can absorb the energy of impact better than the atmosphere can. This is still argued, though. I'd prefer not to try any experiments!

Re:A lot of astronomers don't want to count Pluto

Yes, it would be so much better to just reshape the incoming rock into a long needle so we have destruction confined to only two tiny little spots, including the spot on the opposite side of the Earth.

Get to the asteroid sooner.

The key to preventing an extinction-causing asteroid impact is simply to NOTICE it early enough and have a fast means to get a vehicle there. The reason the asteroid-defeating plans are so hard to create is that we have to wait until the asteroid is near us before we can reach it. By then it's too late. If we can affect it sooner, then exploding it into parts could work really well because the parts would be imparted with enough velocity to spread apart so most of them miss the Earth. Even if an object is headed to strike the earth dead-center, then you only need to deflect it far enough to move it a little more than one earth-radius of distance to the side by the time it gets here and that will make it miss.
(You do need to go a little more than one earth radius because gravity will pull it in - you need to get it far enough out so it will at least slingshot around earth instead of striking it.)

To put this in perspective, if the asteroid was blown up 40 days before impact, that would give us 960 hours for it to move. In 960 hours, an object can move an entire earth radius by going a mere 4.1 miles per hour. So as long as the explosion can impart a velocity of a little over 4.1 miles per hour perpendicular to the course of the asteroid, then the asteroid bits will veer far enough off course to miss. So exploding the asteroid and sending it's parts off in different directions *can* work, if your explosion is big enough to impart that much velocity, and (this is the hard part) you can get a vehicle carrying the bomb out there 40 days before the impacyt.)

The best defense against such an asteroid is a better space program, with faster vehicles that don't require months of prep time to launch. That gives us the time for a simple solution to actually work.

Re:A lot of astronomers don't want to count Pluto

There are no planets with 'subzero cores'.

Re:A lot of astronomers don't want to count Pluto

I've got a couple possible solutions regarding the debate over labeling something a planet.

1. Why not just call all solid [and liquid?] bodies "satellites" ? Asteroid, planet, moon, deathstar, they're all satellites from now on.

OR

2. Redefine "Planet" to mean: Any satellite of a star with enough mass to retain an atmosphere of any [detectable?] pressure.

Rocks come in all sizes, so we ought to ditch the term or define it with respect to something as arbitrary as size.

Our universe is hopelessly complex. Accept it. Part of life as a human is dealing with a world that impossible to fully predict or control. If we didn't have such a world, things would be far less interesting. (we might even be wishing that there would be issues to debate).

Re:A lot of astronomers don't want to count Pluto

Pluto should be labeled an asteroid since it's smaller than even our own moon.

Frankly, I don't understand this line of reasoning. Why does it matter, with regards to whether something is a "planet" or not, whether that thing is bigger than, for example, our moon?

And "asteroid"? Pluto is far, far larger than anything currently considered an "asteroid".

Jupiter and Saturn both have moons that are bigger than Mercury. Do you not consider Mercury to be a "planet", either?

What if Jupiter had a moon bigger than Earth? That's not unimaginable; would Earth then not be a "planet"? In fact, would then nothing be a "planet" except Jupiter, Saturn, Uranus and Neptune?

I frankly don't see what's wrong with (something like) a "planet" being a non-star that's orbiting (directly) around a star. Sure, that makes for some seriously small "planets" relative to what we're used to, but at least it's not an arbitrary and useless definition like (no offense) yours.

And anyway, if you want to add back in your preferred amount of arbitraryness, you can always start referring to "major planets", "minor planets", and so forth.

Re:A lot of astronomers don't want to count Pluto

Quoth grandparent: Pluto should be labeled an asteroid since it's smaller than even our own moon.

Quoth parent: Frankly, I don't understand this line of reasoning. Why does it matter, with regards to whether something is a "planet" or not, whether that thing is bigger than, for example, our moon?

I agree with parent that in this case size really doesn't matter: it's all in how you use what you got.

Historically, Neptune was discovered because it was perturbing Uranus' orbit: its existence was theorized long before it was directly observed. Similarly, Pluto was discovered because it was found that Neptune alone was not sufficient to account for all of Uranus' irregularity. While Pluto isn't very big, its size and orbit are such that it definitely affects the other planets.

In practice then, what we have actually used to distinguish a planet like Pluto from a large body that is not a planet, like Chiron (roughly as big, discovered 1977), is whether the object interacts in a measurable way with known planets. If it does, then accord it planet status because it is clearly part of the planetary system.

In view of this, the new discovery is probably not a planet, unless it has a weird orbit like Pluto and would account for some of the remaining difference between planetary observations and expectations.

But what do I know? IANAA.

Re:A lot of astronomers don't want to count Pluto

Similarly, Pluto was discovered because it was found that Neptune alone was not sufficient to account for all of Uranus' irregularity.

Actually, no. When Pluto was discovered it was found to be too small to account for the irregularity in Uranus's orbit. When they went back and checked, they found there had been a mistake and there wasn't any irregularity to start with. The discovery of Pluto was an accident.

Re:A lot of astronomers don't want to count Pluto

I remember hearing awhile back when the debate was raging about Pluto that to be a planet, the object has to be sufficently large so that gravitational forces caused it to form in the shape of a sphere. So, varous small hunks of debris orbiting the sun definately are not "Planets". At the other end of the spectrum, objects large enough to radiate a certain amount of heat are considered stars. Neither of these definitions are exact, and the astronomy dictionary will probably need to be rewritten with all the recent scientific discoveries emerging, but there are some definitions out there that are not completely arbitrary.

Re:A lot of astronomers don't want to count Pluto

IMO, Pluto should [shouldn't?] be labeled an asteroid since it's smaller than even our own moon [wikipedia.org].

An interesting point, though to be fair, its an arbitrary cutoff. There are moons elswhere in our solar system larger than Mercury, which is indisputably a planet, for example. Also its worth pointing out that our moon is large enough that it and Earth are sometimes called a double planet. Consider this, Luna does not orbit Earth as near the equator as is usual among most other moons. Also, peculiar to all 138 known moons with the exception of Charon, it possesses an orbit where the effect of the Sun's gravity is greater than that of Earth's. Without their host planets, they would float off, wheareas the moon would continue orbiting the sun quite contently.

Re:A lot of astronomers don't want to count Pluto

To be fair, luna is also the closest moon to the sun by a hundred million miles...

Escape velocity

Without their host planets, they would float off, wheareas the moon would continue orbiting the sun quite contently.

I have been interested in Astronomy since I was about six years old. Just over forty years. I have heard what you suggest before -- but only in the last few years. And I don't understand it any more this time than I did on the earlier occasions.

Frankly, I strongly suspect it is a false factoid, like that the internet was built to survive a Nuclear War. I strongly suspect it is a bullshit meme that keep being repeated because it sounds cool, but is completely false.

Pray explain what you mean when you say the other 138 moons would float off ?

I am trying to do the "thought experiment" of silently, quietly erasing the principals of those moons, mass and all. I am finding this difficult to do. I don't believe there is any way this could occur, in our Universe.

So, instead I imagined doing something to accelerate a moon, any moon, to the escape velocity of its principal. What happens then? Well, the object accelerated to just beyond a planet's escape velocity will assume an orbit very similar to that of the Planet it just escaped from. Sometime in the last couple of years ago there was a flap about a small object [slashdot.org] that seemed to have been temporarily captured in the Earth-Moon system. But it turned out to be NASA space debris. It appeared to be the discarded upper stage of an Apollo moon shot.

Re:Escape velocity

false factoid, like that the internet was built to survive a Nuclear War.

Perhaps it's a typo from your part -- original Arpanet was certainly designed such that a network could be built that would survive effects of parts of network to be completed wiped out; something that could happen as a result of nuclear strike. I don't think Arpanet infrastructure itself was more than a (eventually large-scale) prototype (physically, I mean; protocols were certainly engineered correctly), and thus neither it, nor Internet later on, was built to be as tolerant as what protocols would allow.

That Arpanet was designed to survive catastrohic (yet not completely destructive -- there still has to be at least one route between nodes that want to communicate, obviously), is not an urban legend , and should be easily verified from various accounts by its creators.

Technically, the moon is a planet

The moon's orbit is everywhere concave towards the Sun. Therefore, the moon is a satellite of the Sun, and not a satellite of the earth. As such, perhaps it should be called a member of a binary planetary system.

Re:Technically, the moon is a planet

The moon's orbit is everywhere concave towards the Sun. Therefore, the moon is a satellite of the Sun, and not a satellite of the earth. As such, perhaps it should be called a member of a binary planetary system.

Here are pictures and discussion [nus.edu.sg] of the moon's orbit about the sun.

Re:A lot of astronomers don't want to count Pluto

So where's the line between asteroid and planet?

Why does there have to be one? Man's tendency is to compartmentalize things, to make sure everything has a name and that name is unambiguous. Problem is, nature doesn't cooperate. There are always going to be intermediate forms, so there are never going to be definitions that aren't arbitrary.

Same thing applies to species. The nice simple definition "if it can interbreed, its the same species" doesn't always work, and there is no reasonable definition that covers all cases and removes ambiguity.

A decision based on Science, or Politics?

Is this a decision based on Science? Or is it based on Politics and emotion?

Did you know that in 1998 Senator Patrick Leahy, of Vermont, got his State's largest Lake, Lake Champlain, to be reclassified as the 6th Great Lake? [dencities.com] At least as far as the awarding of researh grants. Being considered a "Great Lake" made the academic institutions in his constituency eligible to apply for certain research grants.

There is talk of sending a probe to Pluto. Is it possible that it is easier to sell a probe to "planet Pluto" than to send one to Kuiper-belt object Pluto?

I remember, back in the days when I tuned in to debates as to which newsgroups should be created, the big debate as to whether a new group should be talk.acquaria, rec.acquaria or sci.acquaria.

In Leahy's defence, these were environmental research grants, and I should probably assume he added this line to the bill to protect his constituent's natural environment -- not for the petty partisan purposes.

What about atmosphere?

What we need is a simple rule: If it orbits a star and has an atmosphere, it's a planet. If not, it's not. I.e., things orbiting other planets are moons, even if they have an atmosphere. Things orbiting a star are asteroids (or whatever) if they don't have an atmosphere, no matter how large they are.

Pluto has an atmosphere [spacetoday.net], so it's a planet. What about Sedna? Does anyone know, or must we wait until Monday?

Re:What about atmosphere?

The presence/absence of an atmosphere is not as clear-cut as you might think... Both the moon and Mercury have comparably thin atmospheres. Are they both planets or both asteroids? Pluto may currently have an atmosphere, but it may freeze to the surface as the planet moves away from the sun. Will it cease to be a planet?

Picture of new planet:

Here----> .

Woop de fucking do!

Cue conspiracy theories, New Age freaks, Planet X believers and other idiots. Still, at least this discovery has the redeeming quality of completely fucking up astrology

Re:Woop de fucking do!

I want to know what happened to Quoaor or whatever the hell it's name is. wasn't it planet 10 last year?

Re:Woop de fucking do!

Yeah, it'll probably cost a lot to reprint all the New Age ancient traditions to include a tenth planet.

Re:Woop de fucking do!

Yeah, it'll probably cost a lot to reprint all the New Age ancient traditions to include a tenth planet.

Ten Planets? You haven't been keeping up with here astrology has been going the last twenty-fove years. I know astrologers who use twenty planets, most of which are imaginary. [ Dutch School of Astrology. Germans School of Astrology. The Planets of Alice Bailey, and related flakes.]

This, of course, ignores the two hundred or so asteroids which new age astrologers use. And don't forget the plethora of comets, meteor showers, deep space objects, and other things that may, or may not exist.

And to be sure that you haven't forgotten anything, there are umpteen "Arabic Parts", Midpoints, Orbs, harmonics, ( or something like that) etc.

In short, roughly 10^8 objects that no self-respecting astrologer would omit, if one believes in the validity of all the books on astrology that have been published.

Re:Woop de fucking do!

Now, of course that seems like hogwash, and maybe it is, but it is pretty accurate

Bullshit. If it's accurate, then you could come up with a test to prove it. You could take astrological predictions for an individual based upon his house and compare them with random predictions. These could then be compared for statistical validity, proving once and for all that astrology is accurate.

Wow, if only someone would take the time to perform tests like these. Maybe someone could even make a contest to offer money to anyone who could prove a fantastic claim like "astrology is accurate". [randi.org]

Get it through your skull. It's PROVEN TO BE bullshit. It's always been bullshit, and it will always be bullshit. I've had close dealings with astrologists. I know how some of what they say can seem to be more than just coincidence, but that's all it is -- coincidence and psychology. It's got nothing to do with anyone's "house" or "fate". It's all just bullshit. Don't be a sucker.

Re:Woop de fucking do!

But then the evolutionists would respond with, "10 planets, ten fingers. Coincidence?"

Re:Woop de fucking do!

Wanna know what will REALLY give the conspiracy theorists, New Age freaks, etc? "Sedna" is "Andes" spelled backwards! Everyone knows the advanced Inca civilization lived in the Andes mountains, and there are more than enough wacky theories about the Incas involving aliens and whatnot. Oooh...why is an Inuit god named after backwards-Andes...are the Inuits actually Inca refugees? They're close the Pole, too, and there are already crazy theories about a hole to the interior of the earth where advanced civilizations live, and the Eskimos are somehow related....

Yeah, can't imagine a worse name, really. Backwards-spelled stuff is pure gold in the conspiracy community.

Yeah, but

what isn't pure gold to the conspiracy community?

Astrology = Syncretic Religion

Still, at least this discovery has the redeeming quality of completely fucking up astrology.

Astrology doesn't work that way.

Astrology is syncretic religion [google.com] -- it readily (and inevitably) incorporates new influences.

Like an amoeba, astrology engulfs everything it touches.

In this sense, astrology is rather like paranoia: everything pertains, everything is part of the Big Picture.

Sedna won't fuck up astrology. On the contrary, astrologers will eagerly seize on the idea of this new planet, treating Sedna as one more vacuole in the amoeba.

-kgj

Re:How could

Because you have to be looking at the right place at the right time. Do you have any idea how vast a volume of space we're talking about?

Re:How could

Not to mention that in the Hubble's field of vision, a local planet would be moving much faster than a star millions of AUs out. Imagine looking through binoculars at your sexy neighbor sunbathing in her (or his) yard. You might not see the gnat flying a foot in front of you, because you're not focusing there, so it would just be a blurry fuzz, possibly ignored by the eye if visible at all.

The binoculars also limit or eliminate local vision while in use, obscuring the approach of your spouse/mother and a disapproving hand. . .:)

Re:How could

It's always been hard to see distant planets because they don't emit light. Hubble can see distant galaxies because they contain lots of luminous objects.

Re:How could

"FAR" is a very vague thing in space.

I hear they're going to adopt the new distance measures 'hither' and 'yonder' so normal folks will have a better understanding, at least in galactic terms, of where things are.

I wonder what is so important....

I wonder what is so important that NASA is going to wait until Monday. Maybe they will be unveiling something else at the same time?

--
Real-time deal updates [dealsites.net]

Re:I wonder what is so important....

It's a standard rule of Public Relations. Never announce anything between Friday at 4pm till Monday at 8am.

The reason being that news outlets are not at full capacity during the weekends, so any news announced over the weekend won't get as much coverage. If NASA announced the news today, it will be covered on the Sunday evening news, and never again since that piece of news was already done, even when not many saw it.

You can notice this practice when someone famous dies over a weekend. There will be an immediate announcement saying that the person is missing or very ill or something of the sort, then make the announcement on Monday.

Re:I wonder what is so important....

It's a standard rule of Public Relations. Never announce anything between Friday at 4pm till Monday at 8am.

Unless, of course, it's something you have to announce for some reason but don't want most people to hear. Then late Friday afternoon is the perfect time to announce it. Politicians do this a lot. It would probably be quite instructive to review Friday late-afternoon press releases from the White House, for the last two or three decades.

Re:I wonder what is so important....

"I wonder what is so important that NASA is going to wait until Monday. Maybe they will be unveiling something else at the same time?"

It's the monthly bug-report announcement. "A local root vulnerability has been found in the astrology community. NASA rates it as non-critical"