by Alex Boese
Meteors were the obvious candidate, but, although the specks were mere dots, the images displayed huge swathes of the atmosphere almost 2,000 miles wide. This meant that each speck represented something almost thirty miles wide. Any meteor that size would probably cause our extinction.
Instead, they concluded it had to be water vapour. It would take about one hundred tons of vapour to produce specks of the kind they were seeing, but water was the most common substance in the solar system that absorbed ultraviolet light at the wavelength they were observing. It seemed like the logical conclusion.
That much vapour couldn’t be coming from the ground; the dots were too high up. Therefore, it had to be coming from space. And that’s what finally led to the small-comet hypothesis. Frank concluded that small comets, or ‘space snowballs’, must constantly be pelting the Earth. He imagined them having the consistency of loosely packed snow. When they hit the atmosphere, they would vaporize and diffuse, producing the dark, UV-light-blocking patches detected by the satellite. To produce this much vapour upon hitting the atmosphere, each one of these comets would need to be about the size of a house.
The way Frank saw it, there was simply no other explanation. But the problem, which he conceded, was the sheer quantity of these things. It was ‘an alarming number of objects’. He calculated that about twenty small comets were hitting every minute, which added up to ten million per year. This seemed outrageous, but that’s what the satellite data showed. As Sherlock Holmes said, ‘when you have eliminated the impossible, whatever remains, however improbable, must be the truth.’
Frank published these results in the April 1986 issue of Geophysical Research Letters. He did so even though the journal’s editor warned him that making this claim would probably ruin his career. Sure enough, the scientific community reacted with absolute incredulity.
Summoning an ongoing blizzard of space snowballs into existence isn’t something to be done lightly. It would add a fundamental new feature to both Earth’s environment and space. Scepticism was inevitable, and Frank expected this.
What he found, however, was that two questions in particular seemed to perplex people when they first heard his hypothesis. The question most insistently asked was why these comets weren’t destroying satellites or space shuttles. Wouldn’t launching anything up into space be like sending it into a firing range? The next most popular query was why, if these things existed in the quantities he claimed, no one had ever seen them before. It sounded like they would be hard to miss. Frank believed he had satisfactory answers to both questions.
He explained that the space shuttles didn’t get destroyed because the small comets were extremely fragile, like loosely packed snow, and they began breaking up several thousand miles above the Earth, ripped apart by its gravity and electromagnetic field. By the time they reached near-Earth orbit, where the shuttles flew, about 200 to 300 miles high, they were nothing more than a spray of water, thinner than a London fog. This would cause no damage to a shuttle. In fact, it would be almost undetectable. Frank speculated that shuttles had probably been hit by small comets many times.
He added, however, that if a small comet hit a spacecraft in a higher orbit, it would certainly destroy it. But, since space is big and the comets were small, the odds of an impact were extremely low. Still, there had been cases of spacecraft being lost for unknown reasons. Perhaps small comets had been the culprit.
As for why no one had ever seen these comets, the simple answer was that they were very small and dark. Frank believed they were covered by a thin black crust, like a carbon polymer coating, formed by being bombarded with radiation. This made them almost invisible against the backdrop of the bright stars. Plus, no one had been looking for them.
The slightly more intriguing answer, however, was that perhaps they had been seen, many times, but no one had realized what they were witnessing. Frank suggested they might be the underlying cause behind a variety of unusual phenomena. For instance, astronomers had occasionally reported seeing strange-looking fuzzy or ‘nebulous’ meteors that appeared to have a diffuse head as they descended through the atmosphere. Perhaps these were small comets.
Then there was the phenomenon of night-shining, or noctilucent, clouds. These are a type of cloud that can be seen in polar regions, where they form in the upper atmosphere, higher than any other clouds. Because of their height, they catch the rays of the setting sun, even after the sky has gone dark, causing them to glow. Scientists aren’t sure how water vapour gets high enough to form these clouds, but Frank argued that vapour descending from space could provide an answer.
And what about the anomalous reports of ice falling to Earth from clear skies? This is often blamed on passing aircraft, but such reports predate the invention of manned flight. Frank proposed that these chunks might be the remains of particularly large small comets.
Finally, there were the numerous sightings around the world of UFOs. Frank pointed out that a descending vapour cloud might form a saucer-like shape, which could easily be mistaken for some kind of alien craft. If this was the reality behind UFOs, he mused, it would mean, ironically enough, that they actually were extraterrestrial in origin.
Just in case scientists didn’t realize how disruptive these small comets were to conventional wisdom, Frank made sure to spell out some of their more far-reaching implications. He boasted, ‘The textbooks in a dozen sciences will have to be rewritten.’
If they were real, then presumably they had been bombarding the Earth for billions of years, perhaps since it had first formed. In which case, he argued, the comets might have played a role in the development of life by providing the organic material that allowed its emergence.
But that was just the beginning. These space snowballs could also have been the reason for the formation of the oceans. For a long time, their origin was a scientific mystery, but the prevailing belief now is that they formed as a result of the outgassing of molten rocks that pumped steam into the atmosphere which then converted to rain as the planet cooled. Frank insisted that this wouldn’t have been a plentiful enough source of water, especially when one considers how much moisture is lost by evaporation to space. His small comets, he said, were the true, never-ending source.
This led to what was perhaps the most startling implication. Frank estimated that the small comets added about an inch of water to the globe every 10,000 years. This had been going on for billions of years, but it was still continuing. Extrapolating into the future, this meant that the Earth would eventually be completely submerged in water. Kevin Costner’s film Waterworld might have been a prophetic vision.
Waxing more philosophical, Frank argued that the real reason his hypothesis faced so much resistance was because it challenged the prevailing understanding of the relationship between the Earth and the cosmos. Scientists, he said, like to imagine that the Earth is set apart from the rest of the cosmos in splendid isolation. They acknowledge the existence of dangers from outer space, such as the possibility of asteroid strikes or gamma-ray bursts from dying stars, but these all seem comfortably remote. They don’t think that astronomy really has anything to do with our daily lives. His small comets, however, suggested that we aren’t isolated from the solar system at all. The Earth is being affected by them today, in the here and now, rather than in the distant past or future. Making this claim, he believed, had brought down upon him the wrath of orthodox science.
Of course, mainstream scientists didn’t agree that they were terrified of contemplating the cosmic connectedness of planet Earth. They just thought Frank’s hypothesis was loony, and their primary objection was very basic. It seemed to them that, if small comets existed in the quantities that Frank claimed, their existence should be obvious. You wouldn’t need satellite images to intuit their presence.
But they also offered more specific rebuttals. They pointed out that the moon shows no sign of the effect of these comets. If they’re hitting the Earth, they must also be hitting the moon. In which case, why is
n’t the moon covered in water? And why haven’t the seismometers left behind by the Apollo astronauts ever picked up any trace of them impacting the lunar surface?
But what about the specks on the satellite images? How to explain those? Most scientists dismissed them as an instrumental glitch. There seemed to be no other explanation.
This touches on an issue at the heart of science: the relationship between knowledge and the instruments that produce it. It was in the seventeenth century that researchers first began to systematically use instruments such as telescopes and microscopes to extend their senses. These instruments quickly became one of the defining features of modern science. They allowed researchers to discover objects that couldn’t be seen with the naked eye, but they raised a question: how can you know if what you’re seeing is real or an artefact of the instrument? Seeing with your own eyes had always been the gold standard of truth in philosophy, but with the introduction of these instruments, researchers began to claim objects existed that could never be directly seen. You had to trust both the instrument and the skill of its operator.
Sceptics immediately seized on this ambiguity. In 1610, when Galileo used a telescope to discover moons around Jupiter, his critics dismissed what he was seeing as an optical aberration created by the glass of the telescope. And, as instruments have grown more complex, this issue has only grown more relevant. Researchers now routinely use high-tech machines such as electron microscopes, particle accelerators and DNA sequencing machines to make discoveries. But what these instruments reveal isn’t unambiguous. Distinguishing between meaningless static and a meaningful signal can be very difficult. It requires interpretation, and people can disagree sharply about what the correct interpretation is.
Frank was convinced that the specks in the satellite images were a meaningful signal, and, to his credit, he diligently tried to gather more evidence to support his cause. For one brief moment, it even looked like he would be vindicated. In 1997, he triumphantly revealed that images from a second NASA satellite, Polar, showed identical dark specks in the atmosphere. Some of his staunchest critics admitted this gave them pause. It was definitely odd that these specks kept showing up. Perhaps they weren’t just random instrument noise.
However, a subsequent analysis by an operator of the Polar camera revealed that the specks didn’t change in size as the satellite’s altitude varied. This suggested they were, in fact, an artefact. The operator speculated that they might be a result of static in the camera systems. As far as most scientists were concerned, this brought the controversy to an end.
Frank never gave up though. He kept on arguing for the existence of the small comets right up until his death in 2014. Without an advocate, the small comets then faded into obscurity. Unless one counts the specks themselves as a kind of quiet advocate, because they’re still there, refusing to go away, waiting for someone to believe in them and transform them, Pinocchio-like, into real-life comets.
What if the Earth is expanding?
According to astronomers, the universe is expanding. In fact, its rate of expansion is accelerating as the force of a mysterious dark energy flings galaxies apart at an ever-increasing speed. The sun, they say, is also steadily growing larger as it burns through its hydrogen fuel, causing its core to grow hotter and its outer layers to swell. In about six billion years, the sun will be so big that it will entirely engulf Mercury and Venus, rendering the Earth uninhabitable.
Given this cosmic trend of expansion, could the Earth also be growing larger? At first blush, that might seem unlikely, since it’s a rocky planet and rocks typically don’t change in size. But there is a hypothesis which has hovered on the outer margins of geology for the past century that maintains this is exactly the case: the Earth is expanding and will continue to do so into the foreseeable future.
The hypothesis originated in the early twentieth century with the observation that the continents seem to fit together like pieces of a jigsaw puzzle. In particular, the coastline of South America matches that of West Africa almost perfectly.
Around 1910, the German meteorologist Alfred Wegener had become intrigued by this fit, and he came up with an explanation for it, arguing that, millions of years ago, the continents must have been clustered together as a supercontinent before subsequently drifting apart into their present locations. He called this his theory of continental drift. It received a frosty reception from geologists, however, partly because it contradicted the prevailing belief that the continents were permanently fixed in place, and partly because Wegener couldn’t offer a convincing explanation for how the continents could possibly move through the dense material of the ocean floors. So, his theory was relegated to the radical fringe of geology.*
But Wegener wasn’t the only one intrigued by the apparent fit of the continents. Even as his theory was suffering the ignominy of rejection, denounced as pseudoscience by leading geologists, a ragtag group of iconoclasts – including the German geophysicist Ott Hilgenberg in the 1930s and the Australian geologist S. Warren Carey in the 1950s – came to believe he had identified an important problem. Although they didn’t think his solution of drifting continents was a very good one. Instead, they produced an entirely different explanation: the land masses might once have been joined if the entire Earth had originally been much smaller. And so was born the expanding-Earth hypothesis.
The basic concept of it, as envisioned by Hilgenberg and Carey, was that when the Earth first formed, it had been about half its current size of approximately 7,900 miles in diameter, and that, as the hot molten planet cooled, an unbroken rocky crust formed around its surface. In this way, the land masses of the Earth, in their original, primordial state, entirely enclosed the surface of the planet.
Then the planet began to expand. Why? We’ll get to that soon, but for now just imagine the pressure of this expansion fracturing the rocky crust into pieces, creating the continents. These then spread apart as the Earth continued to swell. Magma welled up in the cracks created by the stress of this expansion, and this formed the ocean floor in the ever-widening gaps between the continents.
So, while Wegener had the continents moving across the surface of a fixed-dimension globe, like giant battleships ploughing through the dense material of the ocean floor, the expansion model didn’t have them moving through anything at all. They remained in the same place and only moved vertically upwards, while the creation of new ocean floors enlarged the distances between them. As such, it was a model of continental spread, rather than drift.
One piece of evidence above all else had convinced Hilgenberg and Carey that their Earth-expansion hypothesis was superior to continental drift. They ardently believed that the continents fitted together much better on a smaller Earth.
It’s a simple enough experiment to try: make the continents into jigsaw pieces, but do it on a globe, and then try to piece them together. You’ll discover that, despite the overall appearance of matching contours, particularly the matching coastlines on either side of the Atlantic Ocean, they don’t fit together perfectly. Large, triangular gaps yawn between them. Geologists refer to these gaps as ‘gores’, which gives an appropriately villainous feeling to them. Wegener’s critics were fond of pointing out this poor fit in an attempt to debunk his theory.
What Hilgenberg and Carey discovered was that, if you keep your jigsaw continent pieces the same size, but try to fit them together on a smaller globe, it works better. The gores gradually disappear. If you make the globe small enough, the continents will almost seamlessly enclose the entire surface of the simulated planet. Hilgenberg in particular was an enthusiastic maker of globes of different sizes – his preferred medium being papier mâché – and globe-making became the signature craft tradition of the expansionist movement. Whenever its devotees met up at conferences around the world, they would proudly display their multi-sized globes to each other.
The expanding-Earth advocates did provide other reasons in support of the hypothesis. They pointed out that, unlike any ot
her geological model at the time, theirs explained why there were two distinct types of surface on the Earth: the land and the ocean floor. They also noted that the expanding-Earth model kept the continents fairly evenly distributed across the globe, unlike Wegener’s model, which created what they felt was a crazily lopsided Earth, with a giant supercontinent massed on one side of the planet and nothing but empty ocean on the other. But it was really the issue of the better fit of the continents on a smaller globe that most inspired them. It seemed utterly impossible in their mind that the contours of the continents would match so well in this circumstance just by coincidence.
But what in the world (literally) could have caused the Earth to expand? We’ve now arrived at this enigma. It was an obvious question that couldn’t be avoided. Advocates knew that the mechanism of expansion was potentially the great Achilles heel of their hypothesis, so they expended enormous mental energy trying to dream up explanations for it.
The most scientifically conservative of these (which is to say, the one that least outraged scientists) was developed by the Hungarian geophysicist László Egyed in the 1950s. He proposed that material at the border between the Earth’s core and mantle might be expanding as it underwent a phase transition from a high- to a low-density state, somewhat analogous to the way that water expands in volume as it undergoes the phase transition from liquid to solid ice. If this were occurring around the core, it would push upwards on the mantle, causing a very slow, gradual expansion of the Earth, at the rate of about one millimetre a year.
Other expansionists weren’t content with such a slow growth rate, and they sought out mechanisms that involved far more speculative physics. Carey suggested that new matter might be coming into existence within the Earth’s core, thereby increasing the mass and volume of the planet. He lifted this idea from the steady-state theory of cosmology, which envisioned the continuous creation of matter as the cause of the expansion of the entire universe.* At the time (the 1950s), the steady state was still considered to be a serious rival to the Big Bang theory and had a number of prominent supporters. So, it seemed reasonable to Carey to draw upon it to explain the expanding Earth. Doing so also suggested a parallel between the expansion of the universe and the Earth.