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10 Weird Things About the Earth that Most People Don’t Know

6. The Earth’s atmosphere is slowly leaking oxygen into space.

Earth's atmosphere
Artist’s impression of Earth’s magnetosphere and leaky upper atmosphere. Image credits: ESA/ATG medialab

Believe it or not, Earth’s atmosphere is leaking. Each day, about 90 tons of atmospheric material leaks from the upper atmosphere. Given the vast atmosphere of our planet, 90 tons is a very small leak. Scientists have found out that over the past 800,000 years, atmospheric oxygen levels have dropped 0.7%, but no one knows why and how this is happening. Missions, such as ESA’s Cluster fleet, have investigated this leakage, but many questions remain unanswered.

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The atmosphere of the Earth weighs about five quadrillion tons. At the rate at which our atmosphere is leaking, we are not in imminent danger, yet scientists are trying to understand the reason behind this phenomenon. Researchers believe that understanding the leakage of the Earth’s atmosphere will help them in understanding the atmospheres of other planets. According to them, it might even prove to be crucial in the hunt for habitable planets and extraterrestrial life. (1, 2)

7. According to a study billions of years ago, an asteroid delivered up to half of Earth’s water, and as much as 2% came from the Solar nebula.

Astroid
Image credits: NASA

It is a widely accepted theory that all of Earth’s water is of asteroidal origin. This is primarily because the ratio of deuterium, a heavier hydrogen isotope, to normal hydrogen is similar in asteroidal and ocean samples. But according to a study led by Steven Desch from Arizona State University, asteroids are not the only reason. Desch believes that water also came through the Solar nebula, the clouds of dust and gas left over after the formation of the Sun.

When researchers studied samples taken from inside the Earth close to the boundary between the core and mantle, they found that they contain notably less deuterium. This indicates that hydrogen in water may not have solely come from asteroids. Besides, they have also found helium and neon in Earth’s mantle. These noble gases contain isotopic signatures inherited from the Solar nebula. Using this information, Desch and his team developed a theoretical model related to the origin of water on our planet. According to this model, as much as 2% of Earth’s water came from the Solar nebula. (1, 2)

8. Just like icebergs, mountains have roots that go deep into the mantle. Scientists noticed this when they were measuring gravity, and it wasn’t what they predicted. Also, the mountains grow.

Mountains
(Image 1) Airy models of isostatic compensation. Image credits: MrQuin84/Wikimedia, Pixabay

The middle layer of the Earth, i.e. the mantle, is fluid-like and denser than the top layer called the crust. As a result, the crust floats on mantle. The buoyancy between crust and mantle is called “isostasy.” Various topographic features of the Earth, such as mountains, are stabilized by isostasy and the strength of the crust. When we observe a mountain, we can see its soaring height and peak, but underneath it lies a buoyant “root” of crust that stabilizes it.

The roots of mountains are of low density. They stay penetrated into the mantle. Mountains which are several km high have roots tens of km deep. When erosion removes mass from the mountain, isostasy responds by lifting the entire mountain range up to replace about 80% of the mass removed. This is how a mountain “grows.” High-precision surveys along the eastern margin of the U.S. have revealed that each century, the land rises a few millimeters to a few centimeters. (1, 2)

9. A big earthquake can not only cause other quakes, but large ones, and on the opposite side of the Earth.

Earthquake
(Image 1) The maps above show how large earthquakes (small red circles) trigger other quakes within 30 degrees of their antipodes, or opposite points (green dots). (a) M8.8 quake in Chile, February 27, 2010, followed by ten events (b) M7.6 in the Solomon Islands, 4/12/2014, followed by M6.8. (c) M7.7, 11/14/2007 and M6.8 shown (d) M7.6, 2/2/1975 and M7.0 (e) M7.6 in Nicaragua, 9/2/1992, followed by M6.7 in Indonesia (f) M7.7 event, 10/10/2002 followed by M6.9 in Brazil. Image credits: Nature, Pexels

It is common knowledge that when a large earthquake occurs, it triggers smaller quakes (aftershocks). Aftershocks occur in the same area when the surrounding crust tries to adjust after the fault perturbation. When scientists at Oregon State University studied 44 years of seismic data, they found out another side effect of large earthquakes. They found that earthquakes with an Mw 6.5 or more can trigger other seismic events of more than Mw 5.0. These tremblors can occur within 30º of its antipode. The antipode of a point lies directly on the opposite side of the globe.

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Researchers of this study analyzed the seismic data from 1973 through 2016. The largest recorded earthquake during this period was the 1960 temblor in Chile that measured 9.5. One of the researchers, Robert O’Malley, has stated that the mechanism of these incidents is yet to be understood. Evidence does show that whenever a triggering takes place due to an earthquake, it is followed by a period of quiescence and recharge. (1, 2)

10. According to a recent study, 15 million gallons of mercury is buried in the permafrost of the Northern Hemisphere, and it could begin leaking as global temperatures rise.

Permafrost
Image credits: CBS News

As global warming is raising the mercury in our thermometers, a different mercury is posing a threat to our future. This mercury is buried in the permafrost of the Northern Hemisphere. When researchers from the US Geological Survey studied the core samples from the Alaskan permafrost, they found that since the last ice age, about 15 million gallons of mercury have been trapped in the permafrost. Currently, the mercury reserve does not pose any immediate danger. But, it will impact ecosystems all over the world if the permafrost melts away completely. Due to global warming, the melt has already started in the Arctic.

Once the permafrost melts completely, there would be no more barrier. Then if the mercury leaches into waterways, microbes can transform it into methylmercury, a potent neurotoxin that can cause central nervous system damage and birth defects. This contamination can travel swiftly up the food chain from microorganisms to humans. It will gravely affect the native and other nearby communities. If the mercury gets released into the atmosphere, it can spread all over the world, even affecting people who live miles and miles away from the source. (1, 2)

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