Several stories have appeared in the press this week on a space theme; there have been many variations, but these two excerpts from the Daily Telegraph give a flavour; the first concerns the possibility of a prominent supernova, visible with the naked eye, in the constellation of Orion – the other concerns the possibility that there might be intelligent life elsewhere in the Universe. Both show the enormous pubic interest that exists for anything connected with space, and both show, in their different ways, the pitfalls awaiting us when we try to understand what might, or might not be “out there”. The supernova story, whilst it has been around for while has acquired a whole new lease of life due to the fact that one possible date for it occur is close at hand – 2012; which also happens to be the date predicted by some interpretations of the ancient Maya calendar for the end of the current cycle in human history and has got the pre-destination theorists in a froth.
For those unfamiliar with the word, a supernova is simply an exploding star. Current theories of star formation say that a star, such as our Sun, is a vast nuclear fusion reaction – and just like any other nuclear reaction, it requires fuel to sustain it; when that fuel runs out the reaction will either die down or, in a minority of cases, become unstable and explode. When that happens, for a short time the star can become thousands of times brighter; and when it happens to a star relatively close to the earth the result is a spectacular astronomical event, easily visible to the naked eye.
There have been many descriptions of possible supernovae from the historical record, but perhaps the best known is the 1054 AD event recorded by, among others, Chinese astronomers who reported that a very bright star suddenly appeared in the constellation Taurus where none had been seen before, close to the known star Tau Zeta. Previous instances of this phenomena exist in earlier records, the Chinese called them “guest stars”. The object was said to be so bright that it was visible in broad daylight for a full 23 days. By night, at the height of its intensity, it was said to be as bright as the moon and was enough to cast a shadow in the dead of night. As the star faded, it remained visible for the naked eye at night for more than two years before it disappeared from view. All that remains in the area now is the famous Crab Nebula, which is thought by some to be the remains of the explosion.
The star that is thought to be a candidate for supernova in 2012 is in fact one of the best known in the sky – it’s the giant star Betelgeuse (pronounced “beetle – juice”). For those of you who don’t know it, it is very easy to find right now. Just go out and look at the night sky in a southerly direction and locate the constellation Orion, as in the picture above. It’s very prominent – you can’t miss it, Betelgeuse is the bright red star in the top left. If this star where to go supernova it would be a spectacular and memorable – to find something as impressive visible to the naked eye you would have to go back to the Great Daylight Comet of 1910 (not to be confused with the much fainter Halley’s Comet which appeared later the same year), a massively bright comet visible in broad daylight, and taking up fully 50 degrees of arc in the night sky.
The star Betelgeuse is a massive object, known technically as a red supergiant. If it existed in our own solar system it would extend beyond the asteroid belt and almost to the orbit of Jupiter. Because of frequent changes in luminosity it has proved very difficult to judge how far away it is, the current consensus is that it’s about 640 light years away, but estimates vary from 200 to 1,000 light years. The good news about that being that we here on earth are quite safe from any fallout – we are simply too far away. What we would get would be a once in a century astronomical event that would forever change the night sky. Statements like a “second sun” are wide of the mark, something like the 1054 event is more likely; on that occasion the star was too faint to see before it went supernova, but in this case it will be a familiar and well known star that dies.
Whilst it is indeed possible that Betelgeuse might go nova soon, it’s very unpredictability means that the end might come soon, or it might come any time in the next million years. That I’m afraid is the current state of our knowledge of one of the most visible and most recognisable stars in the sky – we are not sure how far away it is or when it might explode. This tells us something very important about space – that our knowledge of it beyond our immediate solar system is scant and based entirely on theory emanating from what few observations we can make from distance. I mention this, not in order to deride astronomers and astrophysics, whose work I enjoy reading about, but simply to point out that that is the state of our knowledge right now, and until the day arrives that we have the means to travel to those places, it is likely to stay that way.
Now that we have properly established the true status of humanity’s knowledge of the cosmos we can look again at the story that speaks about alien life. A recent survey has been conducted of nearby Exoplanets – that is to say planets that orbit stars other than our sun. The great difficulty with exoplanets is that they are too small to be seen directly from earth, you instead have to try and deduce their presence by observing the star that they orbit and the effect that they have on it. This might be, for instance, changes in their luminosity that could be caused by a planet passing in front of them or looking for effects of gravity from a planet sized object. This last technique is well tested and was in fact used in the 19th century to analyse the orbit of Neptune, from which it was deduced that there might be another planet further out; this was later found by telescope in the 1930′s – it is of course Pluto.
The results of the survey, conducted by Dr Howard Smith of Harvard, author of books both on astrophysics and Jewish mysticism, have shown that the chances of alien life on any of these planets is looking unlikely due to the fact that the planets are either not of the right type, such as gas giants like Jupiter or Saturn; or are small rocky planets like Earth, Mars and Venus but are too close or too far from the sun for the conditions to be anything like Earth. You can say of course, that that is just the small area that we can see and given the enormous size of the galaxy, let alone the universe, then there must be such worlds somewhere further out.
When this view is expressed it is usually said that it is “statistically certain” that there must be life elsewhere. This comes from a formula known as Drakes Equation, after Dr Frank Drake, who proposed it at the first SETI (Search for Extraterrestrial Intelligence) conference in 1960. This formula tries to quantify the likelihood of alien life as follows
N=N*fp ne fl fi fc fL
Where N is the number of stars in the galaxy, fp is the fraction with planets, ne is the number of life-capable planets per star, and the fractions fl, fi, fc and fL representing planets where life evolves, where it is intelligent life, where they have invented long range communications and with the last one, fL, being the period of time when they can communicate.
Looks impressive doesn’t it ? The problem with it is though, that it is currently impossible to feed any real data into this – the best you can do is estimates for some (like the number of stars in the galaxy), but for most of the rest it would be pure guesswork. Any number that comes out of that equation would be, very literally, meaningless. Take the number of life capable planets for instance; although we have very well formed theories on how life evolved here they are in reality just that – theories that happen to fit the few facts that we have. There is no evidence at present that life exists anywhere else other than the earth, although the presence of past surface water on Mars makes it possible there was once something there, even if it was only singe celled. Until we have established that life has evolved in at least one other place, we may just have to accept the Rare Earth theory; that is that idea that far from life being abundant, it is in fact very rare; and may even be unique, at least for our immediate region of space. The SETI program meanwhile is still busily searching the sky, but has long since lost the funding it used to get from NASA, and now runs entirely on voluntary donations.
All this is of little real concern however since there is a much bigger problem for believers in alien life. And it is quite simply that travel to even the nearest star in less than a human lifetime is probably beyond any technology that we possess and is certainly beyond any inclination to do so on the part of any space agency. The only way for us to make contact with alien life would be if their “Voyager” (either the deep space probe or the fictional Star Trek namesake !) happened to stray into our solar system.
Which brings us finally to the meaning of the title of this piece. It’s a pidgin english expression from the Niger Delta that translates into standard English as three simple words that are the beginning of all wisdom, and are the most honest answer that we can give to the questions when will Betelgeuse go nova ? or whether we are alone in the universe ? ……
“I don’t know” !
Copyright ©2011 Savereo John