These, then, are clues which point to a solution to the Pwdre Ser mystery. Yet the full answer must wait for the day when a scientist can both observe and catch a falling ‘star slime’.
Arthur C. Clarke writes on ‘Icebergs of Space’:
One of the subjects we investigated in some detail in Arthur C. Clarke’s Mysterious World (Chapter 2: A Cabinet of Curiosities) was that of objects falling from the sky. This has been happening for centuries before the coming of the Air Age, and has involved an amazing range of materials -as well as living creatures, such as frogs and fish. In some cases there can be little doubt of the explanation. On the theory ‘What comes down must go up’ we asked for eyewitness reports of such ‘lift-offs’ and, as you have seen, were happy to receive some.
The most spectacular and perhaps well-attested of all falls, however, consist of ice, sometimes in masses far too large to be explained as abnormal hail formations. This is a genuine mystery – but now, at last, we have an answer, though it may not be the only one. It involves a distinguished visitor whom I am sure you will all remember. If you don’t see the connection at first, please be patient …
The week before Christmas, 1985, I made my first serious attempt to locate Halley’s Comet. According to the Ephemeris in The Handbook of the British Astronomical Association, it would be almost directly above Colombo soon after sunset; unfortunately, a rather misty sky was suffused with light from the waxing moon, so I had no great expectation of success.
Another observation hazard was the glare of floodlights from the garden of my next-door neighbour, the Iraqi Ambassador. (His concern for security was understandable: a few days later the papers reported a shootout at his front gate with the local Iranians.)
I fitted my 8-in Celestron with the lowest-power eyepiece available (x 50 – even lower would have been better to look for a faint but fairly large object) and set it up on the flat roof, lining up the polar axis by the tiles, whose orientation I’d determined years ago. Such a crude procedure was hardly good enough for astrophotography, but quite adequate for visual observations. When the clock drive is switched on, an object will stay in view for an hour or more before drifting out of the field.
Now I had to aim the telescope at the exact point in the depressingly luminous sky. Luckily, there were some convenient signposts available – the brilliant planet Jupiter, and the stars in Aquarius, particularly the brightest one, Alpha, which is almost exactly on the Equator. By a stroke of luck, so was the comet on the night of 20 December, so once I’d found Alpha Aquarius only a very slight north-south correction should be necessary.
The conditions were such that I couldn’t locate the third magnitude star Alpha visually. No problem; first I got Jupiter in the centre of the field, and adjusted the telescope’s right ascension and declination (the celestial equivalents of longitude and latitude) circles so that they agreed with the planet’s tabulated position in The BAA Handbook. Then I moved east and north along the two circles to RA 22 hours 05 minutes plus 1/2 degree – and there was Alpha in the low-powered finder telescope.
It was nowhere near the middle of the field (after all, I’d only aligned the polar axis by eye) so I made another slight adjustment to compensate for the remaining error. Now I was sure that I was in reasonable agreement with the celestial coordinate system, and was ready for the final step.
Very carefully, I slewed the telescope through the calculated arc – about 10 degrees eastwards and a smidgen north. Then, holding my breath and covering my head with a black cloth like an old-time photographer, I peered into the eyepiece.
I didn’t really expect to see anything. Quite apart from the poor seeing conditions, my field of vision was only 1/2 degree across – about the size of the moon, which is much smaller than most people realize. (Try covering it with your thumbnail some night.) It was more than likely that the residual errors of adjustment had caused me to miss my target, which meant that I’d have to do some searching.
I could hardly believe my luck – there it was, shyly but unmistakably lurking at the edge of the field! A slight twist of the declination screw, and it was properly centred. Honesty compels me to admit that it was not a conspicuous object; just a bit fainter, and it wouldn’t have been visible at all. But it was there, and that was the only thing that mattered.
My first glimpse of the most famous of comets, still heading for its once-in-a-human-lifetime appointment with the sun, has left an indelible photographic image in my memory. It appeared as a misty blob of light, a few times the size of the planet Jupiter as I’d seen it with the same magnification just minutes earlier. Although it grew brighter towards the centre, there was no nucleus – no starlike condensation of light at its core, as is shown by many comets. Nor was I able to see any trace of a tail, though that was not surprising. Halley was still a long way from the sun, and its witch’s cauldron of volatile ices and organic chemicals had not yet come to the boil.
As I watched that ghostly apparition glimmering in the field of my telescope, I could not help thinking that a small fleet of spacecraft was on its way to meet the comet in less than three months’ time. How amazed – and excited -Halley would have been by this rendezvous with the visitor that will always bear his name! And perhaps Giotto, the Vegas and the Planets, when their mountains of data were analysed – a process which could take years – would confirm that comets are indeed responsible for those massive ice-falls from a cloudless sky which have intrigued man for centuries.
Today, of course, many such events can be all too easily explained: lumps of ice up to 12 lb (5.5 kilos) in weight can accumulate on high-flying aircraft until shaken or blown off. Chemical analysis has sometimes revealed their origin; if, as in one report, there are ‘traces of coffee, tea and detergent’, there’s no need to invoke comets (though perhaps that doesn’t exclude UFOs). But we must look for another explanation in the case of the 20-ft (6-m)-diameter block that fell on an estate in Scotland. Maybe a Jumbo jet with serious plumbing problems could produce such a mini-iceberg; however, Boeing 747s were not very common at the time of the report – 1849. Comets, on the other hand, have been around longer than the earth itself; they are part of the debris left over from the construction of the solar system.
It has long been suspected that many, if not most comets consist largely of ice – or, to be more accurate, of ices. In ordinary life, the only variety we encounter is frozen water, but in the extremely cold regions far from the sun where comets spend most of their lives it comes in many other flavours. There’s ammonia ice, methane ice, carbon dioxide ice (well-known in the refrigeration industry under the name ‘dry ice’) and still more exotic varieties. As a comet heads sunwards, most of these vaporize beyond the orbit of the earth; but frozen water can survive not only the increasing radiation but even – if the initial mass is large enough – the frictional heat caused by passage through the atmosphere.
It seems very likely that some ice-falls are of cosmic origin: they are associated with the sonic booms heard when vehicles re-enter the earth’s atmosphere. It’s a strange thought that the largest of all icebergs do not lie off the coast of Antarctica, but drift between the stars.
And at least once during this century, in 1908, one may have crashed upon this planet. The famous Tunguska ‘event’ (see page 73) has long been a mystery because no substantial meteoric debris was ever found. But a mass of ice moving at fifty times the speed of a rifle bullet could do megatons worth of damage, and leave no evidence of the crime. (I recall a murder story in which there was no weapon; it turned out to have been a dagger made of ice. As Einstein remarked, ‘Nature too can be subtle.’)
The idea that there is a lot of ice floating round in space has a disreputable pseudo-scientific ancestry – which may be why astronomers have been slow to accept it. The American collector of enigmas and anomalies, Charles Fort, suggested that there may be ‘vast fields of aerial ice from which pieces occasionally break away’. Except for the word ‘aerial’ this may indeed be almost true.
These speculations on Halley’s Comet have triggered a memory of more than fifty years ago. My very first attempt at a full-length science-fiction story (fortunately long since destroyed) concerned that typical disaster of the spaceways, the collision between an interplanetary liner and a large meteorite – or small comet, if you prefer. I was quite proud of the title: Icebergs of Space – never dreaming at the time that such things really existed. I have always been a little too fond of surprise endings. In the last line I revealed the name of the wrecked spaceship. It was SS – wait for it -Titanic.