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If you start with a false assumption you can come to any conclusion you want. The idea that "NASA" or any other "government" agency will censor scientific data with the aim to "hide the truth from the people" is absurd. If you believe that then there is little point in talking to me because I don't believe it - for the simple reason that I'm involved in the same business and would never contemplate hiding the truth.
People such as those in the Millennium Group have one thing in common - they believe that their pet theory is correct (the "truth") and that it is not accepted because there is an official cover-up to protect some vested interest in the alternative "official" theory. In a recent exchange with one of the Millennium Group, I was told "...you may be interested in knowing that most of the top scientists at nasa also now understand this but cannot say anything as they will no longer be funded or published or have access to equipment if they do..."
Why this person thinks this is not clear. I know of no "top scientists at nasa" who believe their comet theory. But of course I wouldn't be expected to know as they are too frightened to tell me as has been explained. What has never been explained is the reason for wishing to keep an "official" theory over any other one. What possible advantage could "the government" have in favouring one theory over another? Especially in this case one that will be tested in a few years when a comet is visited. (In fact, several comets have already been visited by spacecraft and the data gathered varifies the standard theory - but of course since the mission was intended to varify the standard theory anyway then nothing would be published to the contrary according to the conspiracists.)
Such conspiratists always say "they persecuted Galileo but he was right", and then make the leap that as they aren't believed then they must also be correct. Faulty reasoning!
A little knowledge can be dangerous - as has been said. Couple that with some ignorance and fairy stories are quite possible. Let me try to explain...
The comet's orbit changing.
The idea that the comet is not following its initially predicted path and that it's orbit has somehow changed is a load of rubbish. It shows the lack of understanding of almost every area of science and astronomy. The initial orbit was generated from a few observaions made over less than 3 days. Compared to the million-plus year orbit that the comet has, 3 days is a very tiny arc from which to calculate an orbit. The slightest error in any of those measurements means the calculated orbit isn't right. There are many reasons for errors - comets are rather "fuzzy" and so defining their centre is difficult to begin with, and star positions are not known to perfect precision either. So the orbit gets refined as more and more measures of its position are made over a longer time span and so the errors can be averaged out. Eventually, its "true" orbit is discerned. It may be that it is different from the initial one, or it may be that it is very nearly the same; what is different is not the path of the comet - it is how we have come to measure that path.
Several people asked for the raw observations of the comet's position.
What would the "Millennium Group" do with the raw data anyway? If they understood orbital calculations then there would be no problem. If they understood astronomy then they'd know that the raw data are available from the IAU Minor Planet Centre at the Smithsonian. They are issued as MPECs (Minor Planet Electronic Circulars) which contain all the raw data as well as orbital updates etc. There is no censorship, nothing is hidden. The data available from there will be exactly the same as the data I could give you that I took with my telescope. There is no differnce.
But it takes more than skepticism to understand the observations. One of the questions asked on the Millennium Group web page is "what is a degree?". If the questioner doesn't know this fundamental idea then how are they to understand the finer points of orbital theory?!?!?
To sceptics in general.
It is good to be sceptical - all scientist are sceptical by nature. But being sceptical doesn't mean that you can justify saying that "I believe nothing I'm told until I can personally prove it". Will you stop using your computer because you don't know how a transistor works, or can be made so small that thousands will fit on the head of a pin? Will you stop drinking beer because you don't know how the body metabolises alcohol? Will you stop using your mobile phone until you can prove that the radiation from its transmissions are not going to fry your brain?
The comet will pass close to the Earth in September.
The comet is not going to come dangerously close to the Earth. The quote about it getting close just shows how dangerous a little bit of information can be without any intelligence to understand what is going on. I expect that the simulation discussed on their web page was a view of the orbit of the Earth and comet as seen from a very long way "above" the Earth. When seen from this perspective the paths of the Earth and comet do seem to get close. But when viewed from another angle then their true relationship can be seen - that they miss by a very long way.
The unit of distance that astronomers use for objects within the solar system is called the Astronomical Unit (AU for short). One AU is the average distance of the Earth from the Sun. The planet Mercury orbits about 0.4 AU from the Sun, Venus is 0.7 AU while Mars is 1.5 AU. Pluto - the most distant planet - is about 39 AU from the Sun. That's the scale of our solar system. The comet, when discovered, was about 0.8 AU from the Earth and 1.4 AU from the Sun. Over the next few weeks it closed to about 0.7 AU from the Earth and then their respective orbits took them apart. When the comet is closest to the Sun (July 11 - "T" in the ephemeris) it will be about 0.7 AU from the Sun ("q" in the ephemeris), but on the other side of the Sun as seen from the Earth so almost 1.7 AU away. The comet then starts moving away from the Sun but closer to the Earth again - due to the Earth's orbit. At closest - around the end of September - the comet will be about 0.8 AU away from us, which is about as far as it was at the time of discovery.
My web page gives an ephemeris for the comet - that is a list of positions and distances. The column marked "Delta" is the Earth-Comet distance in AU, while the column marked "r" is the Sun-Comet distance also in AU.
There is also no chance that the comet is about to change its orbit, as some are claiming. No coronal mass ejection (CME) is able to affect comet orbits to the degree that those at the Millennium Group claim.
In 1910 there was great panic amongst some groups because the Earth was going to pass through the tail of Comet Halley. As is obvious, nothing deadly happened. The passage couldn't even be detected. There were reports of a few suicides due to the fear - but then again that also happened with comet Hale-Bopp recently. There will always be a few sick people around to cause such scares - it happens whenever a bright comet appears in the sky.
The missing data in the ephemeris.
The conspiratists say that the most dangerous part of the comet's orbit is when it's behind the Sun. Very suspiciously, the official ephemeris misses out the vital details of what the comet will be doing there. Why? Well, it's nothing sinister - it's just that as the comet isn't going to be bright enough to see, then why waste space printing it. For those interested, anybody can generate an ephemeris for the missing dates with any one of the many commercial planetarium packages available.
This answer was to somebody who didn't believe the "NASA" theory of comets as dirty snowballs and how could they possibly cause the marks on Jupiter that happend when Comet Shoemaker-Levy 9 hit back in July 1994.
Comets are thought to be condensations of ices and rock - the debris left over from the creation of the solar system. The term "dirty snowball" was coined as a simple, easily understood analogy. The actual ratio of ices and rocks is not known and certainly differs with each comet. Now you might think when they say "snowball" they mean something the size of your hand and hence how could something that size make such a mark on Jupiter? The sizes of the pieces that made the marks were thought to be between a few hundred metres and a few kilometres in diameter. The smaller pieces barely left a mark, the big bits certainly did.
Think about the energy stored in a volume of rock and ice 1 kilometre in diameter and traveling at 30 kilometres per second. You might want to try an experiment to help convince you that ice is hard. Go and pick up a small ice cube from the fridge and throw it at a large window pane. Do you think the window will break? It will if you use a rock, but what about ice? And then think of the comparative velocity. You might be able to manage a velocity of a few metres per second, but the comet was going more than a thousand times that fast. The energy content goes up as the velocity squared!
Next, Jupiter's outer layers are gas, not rock (at least that's "NASA's" official theory of the make-up of Jupiter). No crater was left on the surface, only the atmosphere stirred up. They were big marks, but much as predicted by the "official NASA comet theory".
And what was hidden by "NASA"? You may remember some years ago a comet called Halley. Astronomers said that this famous comet would be returning to our skies but that due to the relative position of the Earth and the comet it would not be a particularly bright apparition. It would be a fair sight, but not like it was in 1910. But the media got carried away and said differently and so people were disappointed when it behaved exactly as predicted. With several astronomical "flops" (at least in the public's eye) then the comet collision was not over-hyped to the media out of fear that this would also be a flop. Remember that nobody had seen anything like this before and so it was really down to theories of comet make-up and theories of Jupiter's atmosphere and lots of calculations. Some theories predicted that nothing would happen because comets are too loosely held together, while other theories said that it would be a very big bang indeed. It was in fact viewed as a splendid test of all the theories and everybody waited for the event to see which theory was closest to the truth. It turned out that the best fit to the observations was the "standard" dirty snowball comet model.
There are many papers available which describe the energies involved and all aspects of this event - nothing is hidden, the raw data are available if you know how to use it, and if you can find a mistake in the calculations then your result wouldn't be buried.
E-mail any comments to me at sl@aaocbn.aao.gov.au
Page last updated 1999/07/05
Steven Lee