If there truly is some extraterrestrial Hitchhiker’s Guide to the Galaxy it would undoubtedly list a total solar eclipse as one of the sights to see while taking a break from probing Earth’s natives. Total solar eclipses, called totality for short, are pretty rare here on Earth; a casual observer might see only one or two during their lifetime.

Since the Earth is the only planet we have ever known, we can’t really appreciate how truly lucky we are. The odds of the size of a planet’s moon exactly matching the apparent size of its sun are pretty low. If the moon is too large, it blocks the majestic solar corona visible during totality. If it is too small, then all solar eclipses would be annular, allowing a ring of the sun’s light to pass . The “Goldilocks” combination of Moon and Sun sizes on Earth makes totality possible, and unique in our solar system.

But alas, this beautiful phenomenon is ephemeral, at least in the geologic sense. The lunar disc shrinks slightly every year as the Moon recedes from the Earth; the chance of a total solar eclipse decreases correspondingly. Somewhere near 1 billion years from now, the last total solar eclipse will grace whatever residents of Earth there may be.

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Natural disasters are tragedies that usually strike randomly and infrequently – unless you happen to live in the Huang He River (colonially referred to as the Yellow River) valley in China. In the space of just over 50 years between 1887 and 1943, some 10 million people drowned or died of famine and disease as the result of catastrophic floods.

While particularly deadly, those floods were nothing new to the Huang He. Since 600 BC, the Chinese have recorded over 1,500 floods, earning it the name “China’s Sorrow.” Across the world there are rivers with valleys more populous, the Yangtze for instance. And there are those that flood more often, like the Nile. And there are rivers that carry far more water than the Huang He, such as the Amazon. So why is the Huang He so deadly?

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Yellowstone National Park is a wonder of the natural world. Its geysers, hot springs, and bubbling mud pools are some of the most impressive examples of geologic activity, and amaze even those who have never visited the park (including myself). Yellowstone became the first National Park in the world when President Grant set it aside for all of posterity in 1872. The dawning of the age of the automobile brought a huge surge of interest in the park, and was the inspiration for the Yogi Bear cartoon.

But those early visitors, and the scientists who came just as eagerly, had no idea what they were really coming to see. It wasn’t until the late 1960s that Bob Christiansen, a geologist with the US Geological Survey (USGS) began to realize that the cliffs surrounding the park were really the rim of volcanic caldera. A volcanic caldera forms when the ground collapses because the magma beneath it erupted. Why did it take geologists so long to recognize Yellowstone for what it is? Because usually volcanic calderas are at most 2-4 km in diameter. The cliffs of the Yellowstone caldera stand 65 kilometers apart.

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Few species on Earth communicate as frequently and effectively as human beings, and none so majestically or ubiquitously as whales. Immersed in an environment rich in sound but poor in light, whales and dolphins developed complex communication systems that they use to mate, feed, socialize, and navigate. The “vocabulary” of some types of whales such as the beluga and humpback is expansive, and rivals most non-humans creatures. Others can communicate over vast distances across the abyss. And, while not strictly communication, many dolphin and whale species use advanced echolocation to hunt and navigate.

The means and ends of these communications are most astounding to humans perhaps because we are accustomed to viewing communication as a sign of intelligence, and probably most people believe that humans are the only truly intelligent species on this planet. One way scientists attempt to quantify the intelligence of a species is to measure the ratio between brain size and body mass and compare it to that of a human. While no species matches human brain proportionately, some whale species come very close. Scientists do not agree on the exact level of intelligence of whales, but there are some truly astounding examples of whale communication that provide strong evidence in their favor.

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On July 25th, 2001 a strange rain began to fall over Kerala, India. For three months intermittent reports of colored rains came in from a several hundred kilometer long strip of coastal India. Just prior to the first reported cases of red rains, reports of sonic booms in the Kerala region suggested that perhaps a comet or asteroid had disintegrated high in the atmosphere, a phenomenon known as an airburst. Two scientists, Godfrey Louis and A. Santhosh Kumar, collected samples of the red rain and reported that the red coloration came from some unidentified particle which showed biological activity. Did Louis and Kumar uncover the first hard evidence of alien life here on Earth?

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Humans (myself included) like to think of ourselves as the most important species on our planet, but we are sorely wrong. If we all ceased to be, the world and nearly all of its species would survive–and probably thrive. But the so-called eusocial insects, bees, ants, and termites, fill such important ecological niches that were they to disappear, so too would most of the life on the Earth. Bees are the most prolific pollinators in most of the world’s biomes, while ants and termites both play vital roles in maintaining soil health and decomposing dead plant matter.

The termites are the most ancient social insects and first evolved around 145 million years ago. The first termites were really ancient cockroaches that hosted cellulose-digesting bacteria in their guts. Since then, thousands of new species developed; there are over 2,600 today. Termites flourished almost immediately because they were capable of digesting wood fibers, or cellulose, as few other land animals could. This symbiosis proved particularly successful, and once termites had evolved that capability, they never looked back. In today’s tropical rain forests, as they have for over 100 million years, they are the primary decomposers, consuming almost all of the dead wood and plant material.

Their success can be measured in the millions of tons; termites comprise as much as 10% of the total biomass of all the world’s land animals. The only insects more massive and numerous than the termites are the ants, their mortal enemy. To protect their colonies, the termites evolved a caste of soldiers with highly specialized weapons. Some termite soldiers can spray toxins from their foreheads, others use enormous jaws to destroy invaders, while other have heads so large that they block tunnels and prevent ant invasions.

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Shards, fragments, and ruins are all that remain from the earliest human civilizations ten thousand years ago. Nothing continues to function as it once did; the Earth has ruthlessly erased all that other humans did not destroy. But ten thousand years from now, in a cave in what is now Nevada, a single functional sign of human technological prowess may continue to tick, whether there are humans there to observe it or not. And no, it isn’t Yucca mountain.

The Clock, as its designer Danny Hillis calls it, will stand over 60 feet tall and keep track of every second, minute, day, century, and millennium for at least 10,000 years. Over that time, it will function with near perfect accuracy by occasionally resetting itself automatically using the warming heat of the desert sun. Its pendulum will be powered by the Earth itself – by temperature and pressure changes during the desert night. But its many faces will require winding. Thus if forgotten it will enter a long silence but continue to mark the years as they pass.

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