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6528.  Fri Mar 19, 2004 10:31 am Reply with quote

What is a planet? As we live on one, maybe we all think we know. It's a ball of earth that orbits around a star, innit? However, it's apparently not always so clear.

It's universally agreed that there are four inner planets in our solar system: Mercury, Venus, Earth, and Mars. These are relatively small, mostly made of rock and have solid surfaces. There are also four outer planets: Jupiter, Saturn, Uranus, and Neptune. These are relatively large, mostly made of gas, and have rings around them.

Outside these four lies Pluto, which has been thought for a long time to be a unique, small, and distant planet. However, many astronomers now think it is actually the largest of the Kuiper Belt objects. The Kuiper Belt is an icy ring of asteroids that orbits the sun outside the orbit of Neptune. About 800 of these have been spotted so far, including a few around half the size of Pluto.

Beyond the Kuiper Belt is the Oort cloud, astronomers think. This is (if it exists) a shell of icy proto-comets in very loose, large orbits around the sun - so far away as to be almost halfway to the next star. A new object almost as big as Pluto, and three times more distant, which some astronomers think could be a planet, has been spotted in this area, and has been nicknamed Sedna, after the Inuit goddess of the sea. Sedna's finders think it's the first "Oort cloud object" ever seen. However, the Oort cloud is supposed to be much farther out than Sedna is. So Sedna may be an inner Oort cloud object, or a rogue Kuiper Belt object, or something else entirely.

Or it may be a planet. It all depends on the scientific definition of "planet," which doesn't yet exist. If Pluto is a planet, what does that make Sedna? If Pluto is a Kuiper Belt object, what does that say about Sedna? This is currently a hot topic about cold objects in the world of astronomy.

See the latest issue of Astronomy magazine...

6529.  Fri Mar 19, 2004 10:58 am Reply with quote

The etymology of planet is from "wanderer", isn't it? ie a star which moves around. Not that etymology sheds any light on what we need the word to mean nowadays.

Frederick The Monk
6531.  Fri Mar 19, 2004 12:30 pm Reply with quote

Not only is there a furious debate going on in the astronomical community about what actually defines a planet - they're also arguing about who gets to name them and what they should be named after.

'Sedna' was the Inuit Goddess of the sea who, accoring to some legends, was thrown into the icy waters of the North Atlantic by her father, which must have got him into a bit of trouble with the social services I expect. As such the name seems perfect for an icy Oort cloud body (or planet, or planetoid or whatever) BUT it's only a nickname at the moment and some astronomers are disputing the right of the discoverers to even give it that. They prefer to call it '' 2003 VB12' until the naming board of the International Astronomical Union had passed judgement. Thier concern is that using the name Sedna before that breaks the rule that Solar System bodies are traditionally named after Greek and Roman deities. The head of the IAU naming board has also noted that calling a solar system body by any name before his board have spoken is a breach of protocol which might actually make board members vote against the name Sedna. Touchy, you might think.

This problem has of course arisen before when William Herschel discovered Uranus. Splendid sycophant that he was, he decided to name it after his patron George III and call it 'Georgian Sidus'. Everyone elso thought that was a rubbish idea however and so the planet was eventually named by Johann Bode in 1781 after the father of Saturn.

BUT of course Johann Bode hadn't discovered the planet, so what right did he have to name it? As we know astronomers can be very picky about this. Indeed this problem has lead many modern astronomers (at least until the middle of the 20th century) to refer to Uranus as 'Herschel' instead. So that's as clear as mud then.

Webb, Rev W. Celestial Objects for Common Telescopes - vol 1

6532.  Fri Mar 19, 2004 1:56 pm Reply with quote

Incidentally, have you ever noticed how many new stars and other bodies are discovered by amateur astronomers? the professionals don't have a brilliant record, and occasionally they'll mount propaganda campaigns to distort history. The discovery of Neptune is a prime example.

Here's as good a summation of the official line as any, from

The discovery of the planet Neptune was a triumph of mathematics. While studying the orbit of the planet Uranus, Urbain Leverrier realized that its perturbations suggested the presence of an unknown planet in an orbit beyond that of Uranus. Leverrier promptly calculated where the planet should be found. On September 23, 1846, the astronomer Johann Galle (in Berlin) looked at the indicated spot - and discovered Neptune in less than an hour.

Stunning. But not true.

Charles Fort took the Neptune myth apart over 80 years ago, in his second book, New Lands. Some highlights(*):


In The Story of the Heavens, Sir Robert Ball's opinion of the discovery of Neptune is that it is a triumph unparalled in the annals of science.(6) He lavishes — the great astronomer Leverrier, buried for months in profound meditations — the dramatic moment — Leverrier rises from his calculations and points to the sky — "Lo!" there a new planet is found.(7)

[...] According to Leverrier, there was a planet external to Uranus; according to Hansen, there were two; according to Airy, "doubtful if there were one."

One planet was found — so calculated Leverrier, in his profound meditations. Suppose two had been found — confirmation of the brilliant computations by Hansen. None — the opinion of the great astronomer, Sir George Airy.

Leverrier calculated that the hypothetical planet was at a distance from the sun, within the limits of 35 and 37.9 times this earth's distance from the sun. The new planet was found in a position said to be 30 times this earth's distance from the sun. The discrepancy was so great that, in the United States, astronomers refused to accept that Neptune had been discovered by means of calculation: see such publications as the American Journal of Science, of the period.(8) Upon August 29, 1849, Dr. Babinet read, to the French Academy a paper in which he showed that, by observations of three years, the revolution of Neptune would have to be placed at 165 years.(9) Between the limits of 207 and 233 years was the period that Leverrier had calculated. Simultaneously, in England, Adams had calculated. Upon Sept. 2, 1846, after he had, for at least a month, been charting the stars in the region toward which Adams had pointed, Prof. Challis wrote to Sir George Airy that this work would occupy his time for three more months. This indicates the extent of the region toward which Adams had pointed.

[...] We mention this stimulus to the text-book writers' ecstasies, because out of phenomena of the planet Uranus, the "Neptune-triumph" developed. For Richard Proctor's reasons for arguing that this discovery was not accidental, see Old and New Astronomy, p.646.(15) Philosophical Transactions, 71-492 — a paper by Herschel — an "account of a Comet discovered on March 13, 1781."(16) A year went by, and not an astronomer in the world knew a planet when he saw one: then Lexell did find out that the supposed comet was a planet.(17)

[...] Before the discovery of Uranus, there was no way by which the miracles of the astro-magicians could be tested. They said that their formulas worked out, and external inquiry was panic-stricken at the mention of a formula. But Uranus was discovered, and the magicians were called upon to calculate his path. They did calculate, and, if Uranus had moved in a regular path, I do not mean to say that astronomers or college boys have no mathematics by which to determine anything so simple.

They computed the orbit of Uranus.

He went somewhere else.

They explained. They computed some more. They went on explaining and computing, year in and year out, and the planet Uranus kept on going somewhere else. Then they conceived of a powerful perturbing force beyond Uranus — so then that at the distance of Uranus the sun is not so dominant — in which case the effects of Saturn upon Uranus and Uranus upon Saturn are not so negligible — on through complexes of inter-actions that infinitely intensify by cumulativeness into a black outlook for the whole brilliant system. The palๆo-astronomers calculated, and for more than fifty years pointed variously at the sky. Finally two of them, of course agreeing upon the general background of Uranus, pointed within distances that are conventionally supposed to have been about six hundred millions of miles of Neptune, and now it is religiously, if not insolently, said that the discovery of Neptune was not accidental —

That the test of that which is not accidental is ability to do it again —

That it is within the power of anybody, who does not know a hyperbola from a cosine, to find out whether the astronomers are led by a cloud of rubbish by day and a pillar of bosh by night —

If, by the magic of his mathematics, any astronomer could have pointed to the position of Neptune, let him point to the planet past Neptune. According to the same reasoning by which a planet past Uranus was supposed to be, a Trans-Neptunian planet may be supposed to be. Neptune shows perturbations similar to those of Uranus.

New Lands was published in 1928. The "Trans-Neptunian" planet Pluto was discovered in 1930. Back to Fort, citing astronomers calculations upon the expected ninth planet:

According to Prof. Todd there is such a planet, and it revolves around the sun once in 375 years.(18) There are two according to Prof. Forbes: one revolving once in 1,000 years, and the other once in 5,000 years. See Macpherson's A Century's Progress in Astronomy.(19) It exists according to Dr. Eric Doolittle, and revolves once in 283 years, (Sci. Amer., 122-641).(20) According to Mr. Hind it revolves once in 1,600 years, (Smithson. Miscell. Cols., 20-20).(21)

But in fact:

It takes 248 years for Pluto to complete one orbit around the Sun, but the orbit is so elongated that it actually spends about 20 years of this time inside the orbit of Nepture.


Percival Lowel had discovered perturbations in Neptune's orbit, which he concluded was due to the influences of some as yet undiscovered planet which had to be about 7 earth masses.

Percival Lowell died in 1916, so he didn't get a chance to know of the discovery of Pluto.

The quest for Pluto resumed in the late 1920's when Clyde was hired without an interview to find Pluto, after submitting his drawings of Mars to the Lowell Observatory.

After almost a year of checking photographic plates which contained more than 400,000 stars each, Pluto was discovered.

As it turns out Pluto is much too small to account for the perturbations in Neptune's orbit and its discovery can only be credited to the tenacity of Clyde Tombaugh, who diligently checked plate after plate using a device called a "blink comparitor".[emphasis supplied]

Pluto's mass is the equivalent of 0.0022 Earths.,+perturbations&hl=en&ie=UTF-8

And what of Quaoar, the last candidate for "Planet X" before the current Sedna hype?

Caltech astronomer Charlie Kowal first photographed Quaoar in the early 1980s. Kowal was looking for the so-called Planet X, the alleged 10th planet that some suspect might exist in the outer solar system. Kowal never found Planet X, and he didn't recognize Quaoar for what it is. His photographic plates proved useful, however, to Brown and Trujillo, who did find Quaoar on them and used the information to help determine the object's precise path.

Who remembers Quaoar today? No-one.

The Trans-Neptunian shellgame continues.

(*This is from the resologist website run by a fortean whose legal name is "Mr X". the resologist site holds hypertext versions of annotated Fort, and ought to be visited by everyone who fancies having their received opinions kicked about a bit:

6535.  Fri Mar 19, 2004 7:46 pm Reply with quote

That's good stuff, and it'd be interesting to hear what a full-on astronomer had to say about it. Is Fort always that inarticulate and elliptical? A shame if so.

6539.  Sat Mar 20, 2004 7:10 am Reply with quote

Flash wrote:
That's good stuff, and it'd be interesting to hear what a full-on astronomer had to say about it.

The nearest they come to admitting that the Neptune story is an outright fraud, perpetrated by the scientific establishment of the time, is to say that "traditional accounts need revising," and blame later interpreters.

Here's one way of putting it:

The ever-charming tale of Neptune's discovery does need some readjustment, if it is to retain its credibility. The traditional tale has depended unduly upon interpretations that were given only after Neptune's discovery. It is necessary to disentangle such post-discovery reconstructions from historical events. This website reproduces archived documents as have been central to the history of the debate, occasioned by the fortunate rediscovery of Britain's 'Neptune file' (1999) after it had gone missing for several decades. It also re-evaluates the traditional narrative, with the help of this newly-found file. We will assume familiarity with the traditional story (emphasis in original)

(In fact, as Fort shows (by going to the primary sources), the Neptune-fable was invented by the astronomers themselves, at the time.)

Here's another way of putting it -- the Scientific American, responding (by private email)to a reader of Fort, says:

Few articles from the older editions [of Sci Am] stand up well to the test of time (perhaps the same will be said for the articles we are publishing now). Leverrier's planet in the end matched neither the orbit, size, location or any other significant characteristic of the planet Neptune, but he still garners most of the credit for discovering it. Most discoveries seem to have two stories: the person with the most name; and the story of those who did the work/got it right.

This was in response to a 1996 "puff" on the 150th aniversary of Neptune's "discovery", that repeated the Neptune fable in its entirety as though it was the truth -- "This discovery is perhaps the greatest triumph of science upon record. [...] He calculates its place in the heavens, with such precision, that astronomers [...] have all succeeded in finding it." -- no retraction was ever published. Read the exchange at:

(One of the pages linked to from this site contains the following: "More than two centuries earlier, in 1613, Galileo observed Neptune when it happened to be very near Jupiter, but he thought it was just a star. On two successive nights he actually noticed that it moved slightly with respect to another nearby star. But on the subsequent nights it was out of his field of view. Had he seen it on the previous few nights Neptune's motion would have been obvious to him. But, alas, cloudy skies prevented obsevations on those few critical days.")

In general, if you want an honest answer, you'll have to inject an astronomer with sodium pentothal.

Flash wrote:
Is Fort always that inarticulate and elliptical? A shame if so.

His style takes some getting used to. It's "stream of consciousness" stuff. I don't think inarticulate really covers it, nor elliptical (personally, I love his style, but that may just be a personal thing). As for "elliptical", he is seldom anything other than brutally frank. Have a look at chapter eight of The Book of the Damned. Here, Fort is on about thunderstones and other anomalous objects that fall from the sky:

Dr. Bodding argued with the natives of the Santal Parganas, India, who said that cut and shaped stones had fallen from the sky, some of them lodging in tree trunks. Dr. Bodding, with orthodox notions of velocity of falling bodies, having missed, I suppose, some of the notes I have upon large hailstones, which, for size, have fallen with astonishingly low velocity, argued that anything falling from the sky would be "smashed to atoms." He accepts that objects of worked stone have been found in tree trunks, but he explains:

That the Santals often steal trees, but do not chop them down in the usual way, because that would be to make too much noise: they insert stone wedges, and hammer them instead; then, if they should get caught, wedges would not be the evidence against them that axes would be.

Or that a scientific man can't be desperate and reasonable too.

Or that a pickpocket, for instance, is safe, though caught with his hand in one's pocket, if he's gloved, say: because no court in the land would regard a gloved hand in the same way in which a bare hand would be regarded.

That there's nothing but intermediateness to the rational and the preposterous: that this status of our own ratiocination is perceptible wherein they are upon the unfamiliar.

Dr. Bodding collected 50 of these shaped stones, said to have fallen from the sky, in the course of many years. He says that the Santals are a highly developed race, and for ages have not used stone implements -- except in this one nefarious convenience to him.

All explanations are localizations. They fade away before the universal. It is difficult to express that black rains in England do not originate in the smoke of factories -- less difficult to express that black rains in South Africa do not. We utter little stress upon the absurdity of Dr. Bodding's explanation, because, if anything's absurd everything's absurd, or, rather, has in it some degree or aspect of absurdity, and we've never had experience with any state except something somewhere between ultimate absurdity and final reasonableness. Our acceptance is that Dr. Bodding's elaborate explanation does not apply to cut-stone objects found in tree trunks in other lands: we accept that for the general, a local explanation is inadequate.


A great many scientists are good impressionists: they snub the impertinences of details. Had he been of a coarse, grubbing nature, I think Dr. Bodding could never have so simply and beautifully explained the occurrence of stone wedges in tree trunks. But to a realist, the story would be something like this:

A man who needed a tree, in a land of jungles, where, for some unknown reason, every one's selfish with his trees, conceives that hammering stone wedges makes less noise than does the chopping of wood: he and his descendants, in a course of many years, cut down trees with wedges, and escape penalty, because it never occurs to a prosecutor that the head of an ax is a wedge.

The first time I read that I almost choked with unexpected laughter.

In fact, ch8 of TBotD is a very good starter.

6841.  Sat Apr 17, 2004 6:00 pm Reply with quote

So, if the perturbations of Neptune aren't caused by Pluto, or Quaoar, or Sedna, or even by a combination of the three, what is causing them? Are the perturbations even there to begin with?

Note now that anomalies in the rotation of Sedna have been discovered:

Sedna, the Solar System's farthest known object, does not have a moon, puzzled astronomers have revealed.

Its slow spin was thought to be due to the gravity of a small, companion body.

Researchers have now discounted this but say the unexpected finding may offer clues to the origin and evolution of objects on the Solar System's edge. [...]

Is there something up with our current understanding of gravity (such as it is)?

Myself I think we *could* be looking at another "Vulcan" fiasco ... even though this one will undoubtedly be less spectacular than the "Vulcan" debacle.

Isaac Asimov on Leverrier and "Vulcan":

Once Leverrier made his suggestion (and the discoverer of Neptune carried prestige at the time), astronomers began searching for possible previous sightings of strange objects that would now be recognized as Vulcan.

Something showed up at once. A French amateur astronomer, Dr. Lescarbault, announced to Leverrier that in 1845 he had observed a dark object against the Sun which he had paid little attention to at the time, but which now he felt must have been Vulcan.

Leverrier studied this report in great excitement, and from it he estimated that Vulcan was a body circling the Sun at an average distance of 21 million kilometers, a little over a third of Mercury's distance. This meant its period of revolution would be about 19.7 days.

At that distance, it would never be more than eight degrees from the Sun. This meant that the only time Vulcan would be seen in the sky in the absence of the Sun would be during, at most, the half-hour period before sunrise or the half-hour period after sunset (alternately, and at ten-day intervals). This period is one of bright twilight, and viewing would be difficult, so that it was not surprising that Vulcan had avoided detection so long.

Charles Fort on Leverrier and "Vulcan":

Leverrier gave the name "Vulcan" to the object that Dr. Lescarbault had reported.

By the same means by which he is, even to this day, supposed--by the faithful--to have discovered Neptune, he had already announced the probable existence of an Intra-Mercurial body, or group of bodies. He had five observations besides Lescarbault's upon something that had been seen to cross the sun. In accordance with the mathematical hypnoses of his era, he studied these six transits. Out of them he computed elements giving "Vulcan" a period of about 20 days, or a formula for heliocentric longitude at any time.

But he placed the time of best observation away up in 1877.

[...]The date:

March 22, 1877.

The scientific world was up on its hind legs nosing the sky. The thing had been done so authoritatively. Never a pope had said a thing with more of the seeming of finality. If six observations correlated, what more could be asked? The Editor of Nature, a week before the predicted event, though cautious, said that it is difficult to explain how six observers, unknown to one another, could have data that could be formulated, if they were not related phenomena.

[...I]f Leverrier had not been himself helplessly hypnotized, or if he had had in him more than a tincture of realness, never could he have been beguiled by such a quasi-process: but that he was hypnotized, and so extended, or transferred, his condition to others, that upon March 22, 1877, he had this earth bristling with telescopes, with the rigid and almost inanimate forms of astronomers behind them--

And not a blessed thing of any unusuality was seen upon that day or succeeding days.

[...] It is our acceptance that there were many equally authentic reports upon large planetary bodies that had been seen near the sun; that, of many, Leverrier picked out six; not then deciding that all the other observations related to still other large, planetary bodies, but arbitrarily, or hypnotically, disregarding--or heroically disregarding--every one of them--that to formulate at all he had to exclude falsely. The d้nouement killed him, I think.

As we all know, GR accounted for the eccentricities of Mercury's orbit without the need for a "Vulcan" to work it all out nicely.

(Incidentally, if you want to see scientific-supremacists at their airbrush-wielding best, check out the following ~ ~ which regurgitates whole the fictitious "triumph" of Leverrier, while bigging it up as "a great embarrassment to astrology". On the subject of Vulcan, the author is content to note that
LeVerrier died in 1877 and so never knew the solution to the mystery of Mercury's orbit.

Which is the truth, but not the whole truth, and certainly not nothing but the truth).

6843.  Sun Apr 18, 2004 9:16 pm Reply with quote

Sorry to be a bit naive about all this, but who fiirst named our own planet "Earth", and why?

Frederick The Monk
6854.  Mon Apr 19, 2004 10:58 am Reply with quote

According to the US Geological Survey:

The name Earth comes from the Indo-European base 'er,' which produced the Germanic noun 'ertho,' and ultimately German 'erde,' Dutch 'aarde,' Danish and Swedish 'jord,' and English 'earth.' Related forms include Greek 'eraze,' meaning 'on the ground,' and Welsh 'erw,' meaning 'field.'

My wife says this sounds a bit dodgy however so I'll ask her to look into it further.......

6858.  Mon Apr 19, 2004 2:54 pm Reply with quote

"Aardvark" = what, "earth-pig", or something? It's all coming together at last.

Frederick The Monk
6870.  Tue Apr 20, 2004 3:23 am Reply with quote

Indeed Mr. Flash.

A nocturnal, burrowing southern African mammal, Orycteropus afer, which is characterized by a long snout and tongue for eating ants and termites. The name "aardvark" is Afrikaans for "earth pig."


7090.  Fri May 07, 2004 7:58 am Reply with quote

Fascinating article in the recent 'Astronomy' magazine, about the earliest period of the universe, summarised here:

One of the problems for cosmologists is how to observe or deduce what went on before the formation of stars. Abraham Loeb and Matias Zaldarriaga from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts calculated that it should be possible to detect the very first atoms in the early universe by looking for the shadows they cast.

The ability to decipher these shadows rests on radio-wavelength observations of the cosmic microwave background (CMB) radiation - highly redshifted photons left over from the Big Bang.

Reversing the current expansion of the universe leads to the conclusion that for the first few hundred thousand years after the Big Bang, a dense fog of ionized gas existed. The cooling of this allowed hydrogen atoms to form. These clumped together to form enormous clouds that absorbed all light energy, shrouding the 20-100 million year-old universe. Loeb and Zaldarriaga used a newly developed shadow technique that can reveal regions with fewer photons that are colder than the surrounding CMB, and thus mapped primordial hydrogen clumps as small as 30,000 light-years across.

Loeb explains that this method allows them to see the epoch of inflation, during which fluctuations in the distribution of matter are believed to have been produced, and allows them to determine whether neutrinos or some unknown type of particle contribute substantially to the amount of 'dark matter' in the universe.

The main problem in detecting these signals lies in the low frequencies, where terrestrial sky-noise is high and Earth's atmosphere naturally opaque. Space-based instruments will be the best way round this, but in the meantime the next generation of radio telescopes, starting with the Low Frequency Array (LOFAR), which is scheduled to begin the search in 2006, may be the first to detect these ancient cosmic shadows.

7102.  Sat May 08, 2004 4:09 pm Reply with quote

Hi there, first post here :-)

Fascinating article indeed.

There's still the small matter of the 'ionized soup' that existed up to 300,000 years after the big bang. Don't see how they'll ever see into or past that to see how it really all started.

Before that time all of the protons and electrons existed as free ions moving around in a plasma. Every time that a proton snatched an electron it would be zapped by a photon with high enough energy to rip them apart again. Only after about a few hundred thousand years was the average temperature low enough that the protons could hold onto their electrons to form neutral hydrogen atoms. This period is referred to as the epoch of "recombination" (in general when atoms become neutral after being ionized we talk of them recombining...

That soup seems by its very nature to need to be uniform right up to the point it was cool enough, at which time you can imagine small variations quickly appearing, and growing to become larger and larger.

src: The Cosmic Microwave Background

7103.  Sat May 08, 2004 4:54 pm Reply with quote

Hello synner, and nice to meet you in a virtual kind of way :-)

That's an interesting point you made about the variations - I suppose that's what accounts for the 'lumpiness' of matter once it started clumping.

7119.  Mon May 10, 2004 10:51 am Reply with quote

But why should this primeval soup cool down? It presumably extended throughtout the universe; so where did all the excess heat go to? This 'Where did the Universe begin?' problem seems to me to be the modern equivalent of 'How many angels can dance on the head of a pin?' Who knows? Who cares?

Give me Discworld any day. At least you know where you are there, even if you're caught in the circumfence staring down at the Great A'Tuin.


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