Jay L. Wile's Blog, page 22

Directed Evolution Wins Nobel Prize

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From left to right: Dr. Frances Arnold, Sir Gregory Winter, Dr. George Smith

(Credits:Beavercheme2, Aga Machaj, Univ. Missouri-Columbia)

Yesterday, the Royal Swedish Academy of Sciences announced that the Nobel Prize in chemistry will be shared among three scientists who all used directed evolution to engineer proteins that solve problems. A reader who saw a news story about the announcement asked me to explain what “directed evolution” means, and I am happy to oblige. In directed evolution, scientists use the concepts of variation and selection to take a molecule that already exists in nature and adapt it to do something that they want it to do. Using a concrete example that comes from the research of Dr. Frances Arnold (one of the recipients) is probably the best way to explain the process.

Dr. Arnold’s lab started with a naturally-occurring enzyme charmingly named P450 BM3. Enzymes speed up specific chemical reactions, and P450 BM3 speeds up the reaction in which an oxygen atom is inserted between a carbon atom and a hydrogen atom in a fatty acid molecule. This is an important step in the process by which a living organism breaks down fatty acid molecules. Dr. Arnold’s lab was interested in doing the same kind of reaction, but on a different type of organic molecule: a small alkane. The enzyme P450 BM3 couldn’t initially do that. However, it could weakly speed up that reaction on large alkanes.

Since the enzyme could at least do that, Dr. Arnold thought that she could “tweak” it until it did exactly what she wanted it to do. However, enzymes are absurdly complicated molecules, and human science isn’t very good at making or understanding them. So she decided to let better organic chemists (bacteria) do the heavy lifting. Her lab took the gene that tells bacteria how to make P450 BM3 and subjected it to mutations. They then saw whether or not the resulting enzyme made by bacteria was any closer to being able to do what they wanted it to do. Maybe it did a better job speeding up the reaction on a large alkane, or maybe it was able to speed up the reaction on a shorter alkane. If that was the case, they saved that gene and allowed it to mutate more, seeing if any more progress could be made. If not, they threw it away and tried again.

This is why the process is called “directed evolution.” Dr. Arnold’s lab induced mutations (which are a source of genetic change in organisms) and then selected any enzyme that ended up being better at what they wanted it to do. With enough of those steps, they were able to get what they wanted: an enzyme that inserted an oxygen atom between a carbon atom and a hydrogen atom in a small alkane. In the end, the process had changed just over 2% of the molecule, but that was enough to change it from an enzyme that acted on fatty acids to one that acted on small alkanes.

Why go through this process? Why not just look at the molecule, decide what needs to be changed, and then change it? Because that’s beyond the reach of our technology and understanding. We just don’t understand chemistry well enough to decide what changes would have to be made and then do them. However, we can make random changes using mutations, and then use bacteria to build the mutant enzymes. We can then see how the mutant enzymes behave and either keep them or throw them away, depending on how they function.

To me, what’s really interesting about this result is that the change produced is incredibly limited. It’s not that the lab starts with an enzyme that speeds up one kind of reaction and produces an enzyme that speeds up a completely different reaction. The lab doesn’t even start with an enzyme that speeds up the same kind of reaction on a different type of molecule. They start with an enzyme that already does what they want it to do, just on a larger version of the molecule and not very well. They then tweak it to do the job better and on smaller versions of the molecule.

No don’t get me wrong. I am not saying this isn’t a great accomplishment. It most certainly is! However, I do think it helps to demonstrate something that creationists have been saying for a long, long time. Yes, evolution can produce change. However, that change is severely limited. Through the process of evolution, I can “tweak” an enzyme to be better at a job it doesn’t do very well. In addition, I can slightly alter the kinds of molecules it will act on. However, I can’t start with one enzyme and then produce an enzyme that does a completely different job. That’s beyond the scope of laboratory-based directed evolution.

Can natural evolution do what directed evolution cannot? I doubt it. Consider what Dr. Arnold points out:

Clearly, natural proteins are subject to additional constraints not present in most laboratory experiments, because they must function in vivo while minimizing deleterious interactions with other cellular components or pathways. In addition, laboratory evolution experiments usually impose a very strong selection for the target protein property, such that mutations that benefit the target property may be selected even to the detriment of other properties.

So while directed evolution is free to mutate things like crazy, natural evolution operates under a lot more constraints. To me, that means natural evolution is even more limited than directed evolution.

One Common Ediacaran Was Probably an Animal

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A fossil similar to the one in which cholesterol remnants were found. (click for credit)

Several years ago, I wrote about the enigmatic fossils found in Ediacaran rock. Most scientists think such rocks are 635-540 million years old, and the fossils found in them have been the source of much controversy. Some paleontologists think they were “primitive” animals, some think they were lichens, some think they were fungi, some think they were giant protozoa, and some think that many of them aren’t even fossils. Well, based on some recent research, one Ediacaran fossil (Dickinsonia – an example is shown above) was most likely an animal.

The research was done by a team of scientists from Australia, Russia, and Germany. They collected Dickinsonia fossils from Ediacaran rock found on a cliff near the White Sea in Russia. This rock is thought to be 558 million years old. They found a thin layer of organic film on top of the fossils, and they chemically analyzed that film. They found cholestane, which is a chemical remnant of cholesterol. It is important to note that they didn’t find cholesterol itself. They found a decay product that indicates the one-time presence of cholesterol.

Why is this important? Cholesterol is a common component of animal cells, but significant amounts of it are not found in lichen, protozoa, or fungi. Thus, the one-time presence of cholesterol indicates that these fossils were animals. But couldn’t the cholestane be contamination? That’s a possibility, so the researchers chemically analyzed the rocks surrounding the fossils. In those rocks, they found little cholestane. Instead, they found the remnants of steroids that are commonly found in algae. So the cholestane is definitely associated with the fossils themselves and is probably not the result of contamination.

If a large number of the Ediacaran fossils end up being classified as animals, I think that will add to the long, long list of problems with flagellate-to-philosopher evolution. Since these fossils are supposed to have come before the better-known fossils found in the Cambrian, they would represent either the animal ancestors of the Cambrian organisms or some evolutionary offshoot that came from those animal ancestors. Either way, evolutionists are now faced with the task of trying to figure out some fairly close evolutionary relationship between the Ediacaran organisms and the Cambrian organisms. Given that these two sets of fossils are so radically different from one another, I suspect that will be a daunting task!

A Failed Test of Fossil Record Interpretation

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When you read about earth history in most textbooks, lots of definitive statements are made concerning events that occurred in the distant past. For example, in Biology: How Life Works, Volume 1 (Morris et. al., Macmillan 2014, 2016), students are told:

A giant meteor struck Earth 66 million years ago, causing the extinction of dinosaurs and many other species…Researchers have documented other mass extinctions, but the event that eliminated the dinosaurs appears to be the only one associated with a meteorite impact. (p. 7)

Any unsuspecting student reading those words would think that we know that the mass extinction of dinosaurs occurred 66 million years ago, that it was definitely cause by a meteor impact, and that there have been other mass extinction events as well.

The problem, of course, is that definitive statements like the ones above come from interpretations of the fossil record. The fossil record itself is spotty at best, and the interpretations are based on all sorts of unverifiable assumptions. So the obvious question becomes, “How accurate are those interpretations?” That’s awfully hard to test, since we can’t go back in time and confirm them. However, the great thing about science is that original thinkers can come along and figure out ingenious ways to test what you might think is untestable.

A team of researchers from the Florida Museum of Natural History, the University of Bologna, the University of the Bahamas, and the State University of New York at Geneseo decided to test how well we know things like the mass extinction events discussed in the textbook I just quoted. They took a series of geological samples from the Po Plain in Italy that are supposed to represent what went on over the past 126,000 years. They specifically examined the mollusks in those samples, which leave behind hard shells.

Their test was both simple and brilliant: Imagine that a mass extinction event occurred right after the samples were taken, and all 119 identified species of mollusks that are currently living there had been wiped out. Would this hypothetical mass extinction be properly interpreted from the fossil remains in the geological samples that had been taken? Not surprisingly, the answer was a solid, “No!”

Think about what the fossil record from the Po Plain should show if such a mass extinction occurred. There should be fossils of most of the 119 species of mollusks in the uppermost layers of the geological samples, right? After all, if the mass extinction happened after the samples were collected, the 119 mollusks would have been leaving fossils behind throughout the entire time the sediments that preserved those fossils were being laid down. Now, of course, fossilization is a rare event, so you wouldn’t expect all 119 species preserved in the uppermost layers. However, you would expect a healthy representation, right?

There were only 6 of the 119 species found in the uppermost layers of the geological samples. Had the researchers been interpreting the fossil record in the traditional way, they would say that most of the mollusks had died out long before the hypothetical extinction event. Even worse, they found that there were clusters of species that all disappeared from the fossil record at specific times. If it weren’t known that those species are still alive and well in the Po Plain today, each of those events in the fossil record would be interpreted as an extinction event! In other words, despite the fact that we know all 119 species of mollusks are alive today, the interpretation of the fossil record would indicate that the vast majority of them are extinct, and they died off in groups at several different times in the past. As the authors state:

Stratigraphic distribution of extant species demonstrates that interactions between ecological preferences of organisms and processes of sediment accumulation produce systematic changes in occurrence rates and sampling probabilities of taxa along a sedimentary succession. The resulting non-random truncation of stratigraphic ranges leads to clustering of LOs [last occurrences of the fossils] at specific sequence stratigraphic positions distorting the relative chronology of species extinctions. Such patterns can easily confound interpretations of the timing, duration and ecological selectivity of mass extinction events.

In other words, if you interpret the fossil record in the traditional manner, you come to false conclusions. That’s because the traditional interpretation of the fossil record ignores the factors that lead to species not fossilizing in specific regions and under specific conditions. Because of that, it will produce a distorted record of natural history.

Of course, this doesn’t indicate that the fossil record is worthless! There are a great many things we can learn from it. However, as this study makes clear, definitive statements, especially ones about the chronology of events in earth’s distant past, cannot be made using it.

Are All Animals Really Omnivores?

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An alligator eats a pond apple (courtesy of the Everglades NPS)

I was teaching one of my online biology courses yesterday and discussed something virtually every biology student learns: classifying organisms as producers (who make their own food), consumers (who eat other organisms for food), or decomposers (who decompose dead organisms for food). I then mentioned that consumers can be further classified as herbivores (eating only plants), carnivores (eating only animals), or omnivores (eating both plants and animals). I then asked the students how they would classify an alligator. Of course, they classified alligators as carnivores. I then showed them the picture above. That alligator is eating a fruit (a pond apple) on purpose.

It has long been known that alligators and crocodiles ingest plant material, but it was originally thought to be accidental. Perhaps the alligator was biting for a fish, missed, and took in some plant material that was floating in the water. However, recent research shows that in most species, the ingestion is probably not by accident. It is a part of the dietary strategy.

After class, I was looking at the scientific literature and ran across an incredible report about a similar phenomenon in bonnethead sharks. Once again, it has been well known that these sharks ingest seagrass, but it was thought to be accidental. Furthermore, since a carnivore’s digestive system is tuned towards breaking down meat, it was thought that the sharks gained no nutrition from the accidentally-ingested grass. We now know that this is definitely not the case.

The authors of the study fed bonnethead sharks a diet that was mostly seagrass with just a bit of squid. The seagrass had been labeled with a specific isotope of carbon (carbon-13), which makes up only about 1% of naturally-occurring carbon. This allowed the them to identify the chemicals from the seagrass and figure out what happened to them after the seagrass had passed through the sharks. They found that the sharks were actually digesting the seagrass and using it for nutrition. In fact, even though their diet was 90% seagrass, the sharks gained weight! Finally, the authors found that the sharks’ digestive tracts showed the activity of enzymes which are designed to break down plant matter. They write:

We show that a coastal shark is digesting seagrass with at least moderate efficiency, which has ecological implications due to the stabilizing role of omnivory and nutrient transport within fragile seagrass ecosystems.

If sharks and alligators can eat and digest plant matter, probably all animals we think of as carnivores are at least capable of eating and digesting plant material. Combine that with the fact that animals thought to be strict herbivores have been found deliberately eating other animals, and we come to the strong possibility that all animals are really omnivores.

Of course, one “take home” message from all this is that creation is marvelously complex, and our attempts to categorize it are incomplete, at best. However, it also has implications when it comes to the issue of origins. Most young-earth creationists (including myself) think that before the Fall, all animals were herbivores. We also believe in a global Flood, where Noah and his family had to care for different kinds of animals on the ark for a bit more than a year. Some of those animals were carnivores, but they could not have been fed other animals (except perhaps some sea creatures from time to time). Creationists critics often say both situations are impossible, because some carnivores must eat meat, or they will die.

If a species of shark can gain weight on a diet of mostly plants, it is at least conceivable that prior to the Fall and for a year on the ark, the animals that gave rise to the “carnivores” we see today could have lived on a diet of only plants.

Scientists Who Wear Blindfolds

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Dr. Peter Atkins is a legend in the chemistry community. He retired from his professorship at Oxford University in 2007, but not after receiving such distinguished awards as the Royal Society of Chemistry’s Meldola Medal and the American Chemical Society’s James T. Grady-James H. Stack Award for Interpreting Chemistry for the Public. In addition to his publications in the scientific literature, he has written several excellent books. When I taught physical chemistry at Ball State University, I used his Physical Chemistry as my text. The chemistry community owes him a great deal.

Even the best of scientists, however, can purposely blindfold themselves when it comes to reality. Dr. Atkins demonstrates this fact with a piece that was published on Aeon. The article’s title says it all:

Why it’s only science that can answer all the big questions

Anyone with a modicum of philosophical knowledge understands how wrong such a statement is, but if you like, you can read this excellent piece written by a serious thinker, Martin Cothran. It shows the folly of Dr. Atkins’s thinking in stark intellectual terms.

While I don’t pretend to be as smart as Dr. Atkins or Mr. Cothran, I would like to add something to the discussion. When I first read Atkins’s piece, I noticed two huge assumptions that the good doctor makes. It’s clear that he either doesn’t know or doesn’t care that he is making them. Either way, that’s bad. Scientists have to recognize and admit the assumptions they are making, or they are like blindfolded men trying to make sense of their surroundings.

His first assumption comes pretty early:

The triple-pronged armoury of science – the observational, the analytic and the computational – is now ready to attack the real big questions. They are, in chronological order: How did the Universe begin? How did matter in the Universe become alive? and How did living matter become self-conscious? (emphasis his)

Can you spot the assumption? He is assuming that the origin of the universe, life, and consciousness can be investigated with observation, analysis, and computation. That’s a huge assumption. First, it’s not even clear that we can understand consciousness scientifically. Until we figure out how to do that, we can’t address its origin in a scientific manner.

The origin of life is similar. Since it is thought to be composed of one or more discrete events in earth’s distant past, how do we use science to analyze it? Suppose we could actually produce life from simple chemicals in the lab under conditions that might have been present at some point in earth’s past (an unlikely scenario, to say the least). What would such an accomplishment demonstrate? That intelligence can arrange a situation in which life could come from non-life. It doesn’t tell us anything about whether or not it could happen in the absence of intelligence.

But let’s start with something “simpler” – the origin of the universe. We can make observations about the current state of the universe, and we can develop mathematical models that try to simulate the origin of these things. But how do we know that this will give us the actual story of what happened? We don’t. Even if we could come up with a model that is completely consistent with all the observations we currently have (and we are far, far, far from such a model), that doesn’t mean it is correct. It just means it is consistent with everything we know. In the end, then, Dr. Atkins is assuming that we can know enough to distinguish between incorrect and correct models of the universe. Given the fact that the universe is pretty big, I am highly skeptical of the validity of that assumption!

His second (and more important) assumption comes much later in his article. He says:

The lubricant of the scientific method is optimism, optimism that given patience and effort, often collaborative effort, comprehension will come. It has in the past, and there is no reason to suppose that such optimism is misplaced now.

The assumption is glaringly obvious here: We have used science to figure out a lot of things; therefore, we can use science to figure out everything. That’s a major leap of faith! Science has an enormously wonderful track record, and over the long haul, it tends to correct its own mistakes. However, to think that this track record indicates that science can figure out everything is nothing more than a major assumption – one of which I am very skeptical. I think Nobel laureate Dr. George Wald gives a more accurate view of science:

Science goes from question to question; big questions, and little, tentative answers. The questions as they age grow ever broader, the answers are seen to be more limited.

Between Dr. Atkins and Dr. Wald, I think the latter has the more rational view of science.

Another Newly-Discovered Feature of the Human Body!

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Microscope image showing the tunnels that exist between a mouse’s skull and its brain.

(Fanny Herisson/Center For Systems Biology/Mass. Gen. Hosp., Figure 5a in the paper being discussed)

The human body is truly incredible. It has been so intricately designed that we are still discovering new things inside it, despite the fact that scientists have been studying it in detail for nearly 2,000 years! Just a few months ago, I wrote about the discovery of a previously undetected feature of the human body, and just this month, a team of medical scientists from Massachusetts General Hospital, Harvard University, and Dongguk University (South Korea) have discovered something else: channels that connect the skull directly to the brain!

The authors made this discovery while they were investigating how certain immune responses work in the brains of mice. White blood cells, the cells of the immune system, are produced in bone marrow, a soft tissue found inside some bones. The authors developed a technique to identify white blood cells produced in a leg bone (the tibia) of a mouse and distinguish them from white blood cells produced in the skull of a mouse. They induced a stroke in the mouse to activate the immune response and studied what happened. As expected, white blood cells were sent to the brain, but unexpectedly, most of them came from the skull.

Why was that unexpected? It has always been thought that white blood cells must travel through the circulatory system to get to the brain. As a result, it was assumed that any white blood cells found in the brain should come equally from all parts of the body. The fact that most of the white blood cells came from the skull indicated that there must be some “shortcut” between the brain and the skull, so the researchers used microscopes to look at the inside of the skull and the surface layers of the brain. What they found is shown in the image above.

The darkest splotches in the image are bone from the skull. The skull’s bone marrow is labelled in the figure, as is the top layer of brain tissue (labelled “Brain membrane”). Notice that there are “Channels” which connect the skull’s bone marrow directly to the brain membrane. That’s the shortcut the white blood cells took. They traveled directly from the skull’s bone marrow to the brain, making the immune response more rapid than if the white blood cells had to travel through the circulatory system.

Even though the discovery of these “brain channels” was made in mice, the authors examined skull tissue removed from patients who had been through a neurosurgical procedure. They found similar channels that were roughly five times as large as the ones they saw in the mice. Of course, they couldn’t do similar experiments on people, so they don’t know for certain that the channels serve the same purpose in humans as they do in mice. However, it makes sense that they should.

The human body is so fearfully and wonderfully made (Psalm 139:14), I am sure this isn’t the last new feature to be discovered!

Back to School

It’s the beginning of another another academic year. In addition to teaching online courses, I am once again teaching Thermodynamics at Anderson University. I love teaching thermodynamics, because it is a difficult subject, but it explains so much about creation. Unfortunately, many scientists and even some engineers (like Bill Nye) don’t understand it. I hope that my students walk away with a solid grasp of the subject.

Of course, teaching at the university on top of my online courses will make me a lot busier than I should be, so I am not sure how much time I will have for blogging. I will try to write at least once a week, but we will see how that goes. For now, I hope that you enjoy this video, which is the demonstration I did for the first day of class. A variation of the first part of the demo (the aluminum foil heat engine) is in the last book of my elementary science series, Science in the Industrial Age. Students make the engine when they learn about Sadi Carnot, the father of thermodynamics.

Cool “New” Unexplained Phenomenon

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An example of a STEVE event. This one happened on August 17, 2015. (click for credit)

Have you met STEVE? It’s a strange event that has been photographed by several people who spend a lot of time photographing auroras. One of them (Chris Ratzlaff) suggested the name “Steve,” which was inspired by the animated movie Over the Hedge . Apparently, one of the characters in the movie named something he didn’t understand “Steve.” When the scientific community began studying this phenomenon, they kept the name but made it more “scientific.” They called it STEVE for “Strong Thermal Emission Velocity Enhancement.”

Since STEVE events happen where auroras are found, it is reasonable to think that they are related to auroras in some way. However, auroras are visible every night when you are at high latitudes and the viewing conditions are favorable. By contrast, STEVE events are visible only a few days each year, at least according to the photographers who have documented them. Also, auroras produce a glow that spreads wide throughout the night sky, while STEVE events produce ribbons of light.

So what causes these events? Currently, scientists can’t say. The initial study said they might be similar to auroras, which are caused by high-energy charged particles that have been trapped by earth’s magnetic field interacting with molecules in the upper atmosphere. This interaction gives the molecules excess energy, and they emit that energy in the form of visible light, mostly reds, greens, and blues. Scientists looked at satellite imagery that was taken during a documented STEVE event, and they did see charged particles moving at high speeds through the appropriate region of the atmosphere, but they couldn’t say for sure that they were related to the event.

Now, some of the authors of that study have published an analysis that indicates STEVE events are not very similar to auroras. They looked at imagery from the National Oceanic and Atmospheric Administration’s polar orbiting satellites that happened to be over a documented STEVE event on March 28, 2008. It was in the perfect position to see if high-energy charged particles were interacting with the upper atmosphere during the event, and it saw none.

As a result, there is currently no explanation for what causes STEVE events. I look forward to seeing where the research goes on this!

The Global Warming Alarmists Were Wrong (Again)

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The white corals in the picture have bleached (click for credit)

Corals are amazing animals that form reefs which are teeming with life. They eat things that are floating in the water around them, but they also have a mutualistic relationship with algae called “zooxanthellae.” The corals provide the algae with housing, and in exchange, the algae give the corals chemicals they need. It’s a wonderful system that allows both species to flourish.

However, there are times when this system breaks down. When corals become “stressed” (usually by a sudden change in temperature, the intensity of sunlight, pollution levels, etc.), the algae are expelled from the corals. The details of this process are still a mystery, but it usually causes the corals to turn white, as shown in the picture above. Because of that, this process is often called bleaching.

Earlier this year, The New York Times published an article entitled, Global Warming’s Toll on Coral Reefs: As if They’re ‘Ravaged by War.’ It stated:

Large-scale coral bleaching events, in which reefs become extremely fragile, were virtually unheard-of before the 1980s.

That’s the typical “party line” when it comes to those who don’t want to study the issue of global warming seriously. Something bad is happening now, it hardly ever happened in the past, and if we don’t do something about it soon, we are all going to die. Not surprisingly, it just isn’t true.

A recent study examined cores taken from corals in the Great Barrier Reef. These cores exhibit layers, and based on the way corals grow today, they can be interpreted as annual layers. Like counting tree rings, then, you can count coral layers and determine what year the layer formed. While the annual interpretation gets less and less certain the farther you go back in time, it is at least a reasonable way to estimate what was happening to corals in the past.

The authors of the study examined these layers, looking at the year-to-year changes in the rate at which the corals lengthened. Since bleaching events affect coral growth rates, it is reasonable to think that changes in lengthening rates would indicate bleaching events in the past. They used known bleaching events to “calibrate” their analysis, seeing what changes occurred in the cores during observed bleaching events in the past. They then looked at the cores going back almost 300 years.

What the authors found is only surprising to people who read The New York Times and similar sources. They found that coral bleaching events were not at all uncommon throughout the past 300 years, and they were probably more frequent in the past. In fact, they were most frequent in the 1890s and 1740s. The authors also looked at how many corals experienced bleaching in these events. The record was set in the 1850s, with the 1740s, 1670s, and 1690s in a dead heat for second place. Based on their analysis, there is nothing unusual happening currently when it comes to coral bleaching.

It is really common for people to see something unusual happening today and claim that such things are being caused by recent human activity. While that can make for good politics, it makes for lousy science.

Clouds that “Glow” in Twilight are Becoming More Common

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Noctilucent clouds over Uppsala, Sweden (click for credit)

The picture above shows a phenomenon that can be seen during the summer by people who live at latitudes of 50-65 degrees. They are called noctilucent (“night shining”) clouds, and they appear to glow in the twilight sky. They aren’t actually glowing, and they aren’t really clouds, either. Instead, they are bands of ice crystals that are way above the clouds, in an upper part of the atmosphere called the mesosphere. There is very little water in the mesosphere, and it is extremely cold there. When conditions are right, however, what little water that exists there can freeze into tiny ice crystals, forming short-lived “clouds.”

Why do they appear to glow? Well, at twilight, the sun is below the curve of the earth, so you can’t see it directly. However, if you were up higher, you could still see it. Indeed, this video shows a drone observing the sunset at a height of 80 feet and then rising to 400 feet to see the sun set again. So even though you can’t see the sun once it sets, higher altitudes still “see” it. That means the sun’s light is still shining brightly on things that are high in the sky, including the ice crystals. Some of that light scatters off the crystals and heads to the earth. If you are at the right place on the earth and it is dark enough, you can see that light, and it looks like the light is coming from the “clouds” themselves. Here is an excellent time-lapse series that shows both noctilucent clouds and an aurora.

Why am I blogging about this phenomenon? Because this year has been an unusually good year for seeing it. Indeed, reports of these “glowing clouds” have tripled this year compared to last year. What’s causing it? According to Dr. Lynn Harvey of Colorado’s Laboratory for Atmospheric and Space Physics, it’s because there is an unusual amount of water in the mesosphere this year. It is also a bit colder than normal. Combine those two effects and you have more ice crystals and therefore more noctilucent clouds.

Why is it wetter and colder this year in the mesosphere? We don’t really know. In fact, noctilucent clouds are a bit of a mystery in general, since they were first reported in the summer of 1885. Whether that means they just started forming then or just happened to be noticed then, we don’t know. However, most other striking atmospheric phenomena had been observed much earlier. Auroras, for example, were reported in ancient china and were named by Galileo in 1619. It’s hard to believe that a similar atmospheric phenomenon that can be seen at the same latitudes existed but remained unnoticed until 1885.

Of course, unlike auroras, noctilucent clouds are rare and short-lived. After all, they occur only in the summer and, in order to see them, it needs to be pretty dark, since sunlight overwhelms the small amount of light coming from the ice crystals. Thus, the sun has to be below the curve of the earth for the observer. However, once the sun is well below the curve of the earth, it no longer shines on the ice crystals in the mesosphere above the observer. This fact might have made them less likely to be observed and, even when they were observed, less likely to be believed, since they would “disappear” after a while.

So it may be that noctilucent clouds clouds are a fairly recent phenomenon caused by human activity, and it may be that whatever human activity is causing them is increasing their frequency. Of course, it may also be a natural phenomenon that ebbs and flows over time. We just don’t know. That’s the great thing about science. There always seem to be more questions than answers!