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The Brocken Spectre, here seen in Poland, is an optical phenomenon in which the observer’s shadow appears to be magnified on clouds or fog below. The Spectre can be observed from mountaintops when the sun is low and behind you, and there’s dense fog or clouds below. It is often accompanied by a glory, a rainbow-like halo that can also be observed when one is between the sun and a layer of clouds, and the movement of the clouds plus the apparent magnification can give the impression of a supernaturally tall ghost being walking the mountain.
The phenomenon is named for Brocken, also known as Blocksberg, a mountain peak in northern Germany long associated with witches and devils in local lore and literature. Another place to see it is the Scottish mountain Ben MacDhui, a frequently fog-shrouded peak where legend has it an unusually tall “Grey Man” resides. It isn’t hard to image how a lone mountaineer—halfway lost and hearing his own footsteps oddly distorted in the mist—could conjure up mythical beings when faced with a ghostly giant in the distance.
A computer simulation of what happens when two spiral galaxies collide. At various points, the simulation stops to show a comparison to pictures of actual galaxy pairs in the midst of this process, as seen from the Hubble telescope. In a few billion years, the Milky Way might undergo this process, merging with our largest neighbor, the Andromeda Galaxy.
The antipode of a point on Earth is the point diametrically opposite it—where you’d end up if you dug a tunnel straight through the Earth. Most land is antipodal to the sea. Above is a map showing antipodal points, with the overlap (orange) showing places where, if you did manage to dig straight through our planet, you’d end up on land. As you can see, if you want to dig straight to China, you better start in Chile or Argentina. Parts of Spain are antipodal to parts of New Zealand, a fact exploited by the first “Earth Sandwich”, a response to a challenge by Ze Frank.
Scientists are interested in extremes. The biggest and smallest, slowest and fastest tend to tell us more about the ultimate rules and limitations that govern all of life than the middle-of-the-road. During a recent trip with the research vessel R/V Knorr, scientists found something remarkable. Drilling sediment cores from the bottom of the North Pacific Gyre, a huge system of currents between North America and Asia, they found bacteria living life as slowly as possible.
Normally, oxygen penetrates only a few centimeters or decimeters down into the seabed. These bacteria, however, were living off oxygen more than twenty meters below the seafloor. There’s very little of either oxygen or organic material for the bacteria to live off, so in order to survive, they must live so slowly that they’re barely alive at all. The researchers measured carbon oxidation and assumed that this corresponds to the bacteria’s oxygen comsumption. By counting the number of cells and measuring the oxygen concentration, they could calculate roughly how slowly the bacteria metabolize. This tapered off at 10-3 femtomoles per cell per day, which equals only seven oxygen molecules per second. That is unbelievably slow. The results were consistent over many core samples from varying conditions, suggesting to the researchers that “these microbial communities may be living at the minimum energy flux needed for prokaryotic cells to subsist.”
The reason the oxygen penetrates so deep is that the sedimentation process is very slow. The bacteria in the deepest layers packed a lunch box while dinosaurs still roamed Earth, and they’re still living off it, as new organic material is unlikely to have entered their realm since then. Since they live so slowly, it’s probable that individual cells are really, really old. This is obviously interesting because life wears down the living, and so the bacteria might have quirky adaptations to be able to repair themselves. It should be noted that no one has studied these bacteria directly, though, so we don’t know (yet) exactly how they work.
Volcanic Sunsets and Years without Summer
On April 10, 1815, Mount Tambora exploded. Tambora is a stratovolcano in Indonesia, and has been overshadowed in the popular imagination by Krakatoa, another Indonesian volcano that erupted in 1883. But Tambora was larger. It was, in fact, the largest eruption in recorded history, topping 7 on the Volcanic Explosivity Index. The casualties are estimated to be around 75,000-90,000, more than any other known eruption. Most interesting from a scientific perspective is the profound effect such eruptions have on the global climate.
1816 was called “the year without a summer” in the northern hemisphere, especially in Europe and North America. Now, the years of 1790-1830 saw a minimum of solar activity, which no doubt contributed to the unusually cold summer. But the reason this year was outstanding even for a cold period was almost certainly Tambora. Put simply, dust and volcanic ashes blocked the sun. Some of the effects, from an old article at The Smithsonian:
In China and Tibet, unseasonably cold weather killed trees, rice, and even water buffalo. Floods ruined surviving crops. In the northeastern United States, the weather in mid-May of 1816 turned “backward,” as locals put it, with summer frost striking New England and as far south as Virginia. “In June … another snowfall came and folk went sleighing,” Pharaoh Chesney, of Virginia, would later recall. “On July 4, water froze in cisterns and snow fell again, with Independence Day celebrants moving inside churches where hearth fires warmed things a mite.” Thomas Jefferson, having retired to Monticello after completing his second term as President, had such a poor corn crop that year that he applied for a $1,000 loan. (…)
In Europe and Great Britain, far more than the usual amount of rain fell in the summer of 1816. It rained nonstop in Ireland for eight weeks. The potato crop failed. Famine ensued. The widespread failure of corn and wheat crops in Europe and Great Britain led to what historian John D. Post has called “the last great subsistence crisis in the western world.” After hunger came disease. Typhus broke out in Ireland late in 1816, killing thousands, and over the next couple of years spread through the British Isles.
In Portugal and Spain, droughts and unseasonally low temperatures caused problems.
The effects could be seen not only in crops and thermometers, but also in art. A survey of paintings by notable artists done before or in the years immediately following major volcanic eruptions shows that sunsets, as seen by artists, were significantly redder immediately following eruptions. The findings correlate well with historic estimates of the Dust Veil Index, a measure of how much dust and aerosols a particular volcano released, compared to background conditions.
Why would volcanic dust in the atmosphere make sunsets redder? The reason the sky is blue at midday and red at dusk and dawn is Rayleigh scattering. Molecules and tiny particles in the atmosphere scatter incoming sunlight. Shorter wavelengths like blue light are scattered more strongly, resulting in a blue sky. However, when the sun is low in the sky, the angle means sunlight must pass through a much larger volume of atmosphere before it reaches us. This causes the bluer wavelengths to be scattered away, leaving reddish light, giving us red sunsets. A denser atmosphere due to a volcanic eruption would exacerbate this effect.
Above are The Lake, Petworth (circa 1827-28) and Sunset (circa 1833), both painted by J. M. W. Turner. The first painting was done before the 1831 eruption of Babuyan Claro, a volcano located in the Phillipines, while the second, redder one was most likely done less than two years after said eruption. One of the most famous red sunsets in art, Edvard Munch’s The Scream, is also speculated to have been inspired by atmospheric conditions after a major eruption, Krakatoa in 1883.
Lonesome George is dead. Since being discovered more than forty years ago, he has been the last of his kind, the Pinta Island tortoise. With him, his species dies. Someone on reddit made this comparison of the Wikipedia page for the Pinta Island tortoise. How did we screw George’s species over? First 19th century whalers killed off a bunch for food on their journeys, then in 1959, fishermen introduced goats to the island. The goat population exploded to over 40,000 in just a few years, and the vegetation on the island was seriously harmed. The goats have since been exterminated and a project is underway to restore the Pinta island ecosystem and reintroduce tortoises to the island, but it didn’t come soon enough to save George’s species.
This could be anything. What it actually is: the distribution of adhesive on a Post-It note, imaged using a scanning electron microscope.
When Life Got Big, or, a Forgotten Architecture of Life
Several times in our planet’s history, all or most of the Earth’s landmasses have been gathered together into one supercontinent. Most well-known is Pangaea, home of dinosaurs. Supercontinents form and disperse cyclically in geological time. 750 million years ago, an earlier supercontinent, Rodinia, broke up. Following this breakup came global climate change, in the form of the Sturtian (725-710 million years ago), the Marinoan (635-600 mya.) and the Gaskiers (ca. 580 mya) ice ages. The latter two were perhaps the most severe ice ages the world has ever seen, with glaciers at sea level within ten degrees of the equator. Some have termed that era the Snowball Earth, although it is likely that there were oases of liquid water in which life could survive.
Up until this point, microbial life, and especially bacteria had dominated the world. Following this period came the so-called Cambrian explosion, a period where most of the animal types that survive to this day rather suddenly (in geological terms) start appearing in the fossil record. This is when things that somewhat resemble macroscopic life as we know it begin to appear.
But the Cambrian starts around 542 million years ago. In between the end of the Gaskiers and the start of the Cambrian was a period called the Ediacara, and there exist an intriguing class of fossils from this era, the Ediacara biota, represented above by Dickinsonia costata. Although multicellular algae had existed for quite some time before, the Ediacara biota represent the first time complex, macroscopic life measured in centimeters and meters evolved on Earth. They were soft-bodied, mostly immobile creatures luckily preserved in sediment, by microbial mats or under beds of volcanic ashes. Fossils have been found on five continents. And these aren’t your ordinary fossils: they’re utterly weird, some of them almost resembling familiar life forms, others “fractal constructions unknown in our modern world.”
The climate changes following the breakup of Rodinia put extra pressure on life to evolve new forms. What evolution came up with was the marine life that evolved into the animal kingdom we know today. When the Ediacaran fossils were first discovered, they were held to be early examples of extant phyla, many of them probably a kind of “prehistoric jellyfish”. But in recent decades, this view has been challenged: the Ediacara have proven much more difficult to put into the existing hierarchies of life. Scientists no longer think all the fossils from this period fit under one umbrella; rather, each specimen is up for grabs.
Some of them are now thought to represent the dawn of animal life, related to sponges and cnidaria (corals, jellyfish, sea anemones, etc.). But we are close in time here to the hypothesized common ancestor of all animal life, and some of the Ediacara may not be rightfully classified as animals at all. The most intriguing of them may actually represent “failed evolutionary experiments”—branches of life that evolved separately from both the prokaryotes and the ancestors of today’s animal and plant life, but that eventually died out:Perhaps the best example of an extinct high-level taxonomic group is that of the rangeomorphs, a group of colonial organisms that exhibited a modular construction of similar, highly fractal elements. These elements were combined as modules to construct frond-, spindle-, comb-, or bush-shaped colonies that ﬁlled most niches in the Mistaken Point ecosystem. Rangeomorph communities are most similar to those of modern, suspension-feeding animals, but it is difﬁcult to relate rangeomorph morphology to any modern animals, and they appear to represent a “forgotten” architecture and construction that may represent an extinct phylum-level stem-group near the base of animal evolution. Rangeomorphs characterized the early stages of Ediacaran evolution, perhaps because their fractal growth and modular construction required less genetic complexity than was required by other animal phyla. Rangeomorphs were unable to compete with later, more highly evolved animals, and occur only rarely in younger Ediacaran assemblages and are not known from any Cambrian or younger assemblages including fossil Lagerstätten.
Right on the border between the Ediacaran and Cambrian periods, around 542 million years ago, the Ediacaran fossils disappear. Vanished from the fossil record. Perhaps they all died out due to some ecological disaster, possibly a temporary drop in oxygen levels, leaving a gaping ecological hole for the conventional animals of the Cambrian explosion to fill. Perhaps the conditions that preserved these proto-animals (which did not have skeletons) disappeared, and the creatures lived on for some time unrecorded in the fossil record. Possibly the most likely explanation is that with the Cambrian explosion, predators started appearing, and primitive, immobile and defenseless creatures such as the Ediacara biota may have been easy targets, driven to extinction by the evolutionary cousins that would replace them.
Astronaut Ron Garan did an AMA on reddit. This photo was his reply when asked, “Have you seen anything when looking down on earth or into space that has you completely awed that is captured in your memory for the rest of your life?” It’s the illuminated border between India and Pakistan, as seen from the International Space Station.
Realizing what this picture depicted had a big impact on me. When viewed from space, Earth almost always looks beautiful and peaceful. However, this picture is an example of man-made changes to the landscape in response to a threat, clearly visible from space. This was a big surprise to me. (…)
The point is not that we can look down at the Earth and see a man-made border between India and Pakistan. The point is that we can look down at that same area and feel empathy for the struggles that all people face. We can look down and realize that we are all riding through the Universe together on this spaceship we call Earth, that we are all interconnected, that we are all in this together, that we are all family.