Today is Earth Day 2023! Celebrated annually on April 22nd, is a global event aimed at raising environmental awareness and promoting sustainable practices to protect the Earth’s natural resources. It was first observed in 1970 in the United States, founded by Senator Gaylord Nelson in response to increasing environmental concerns.
Since then, Earth Day has grown into a worldwide movement. It engages millions of people in over 190 countries to participate in various eco-friendly activities, such as tree planting, clean-up drives, and educational programs.
The event plays a significant role in encouraging individuals, communities, and governments to take action in tackling environmental challenges. These include climate change, deforestation, and pollution, to ensure a healthier and sustainable planet for future generations.
Here are 20 reasons to love, honor and cherish this incredible blue marble that we call home.
The Earth’s days are gradually getting longer due to a phenomenon known as tidal friction. The gravitational interactions between the Earth and the Moon cause this. As the Moon orbits around the Earth, it exerts a gravitational force on our planet. This causes a bulge in the Earth’s oceans, known as tides.
As the Earth rotates, the tidal bulge tries to align itself with the Moon. However, due to the Earth’s rotation, the bulge is slightly ahead of the direct line between the Earth and the Moon. The gravitational pull of the Moon on this bulge creates a torque that acts against the Earth’s rotation. This causes it to slow down. As a result, the Earth’s rotation period, or the length of a day, increases over time.
This process also leads to the Moon gradually moving away from the Earth at a rate of about 3.8 centimeters (1.5 inches) per year. As the Moon’s distance from the Earth increases, the rate at which the Earth’s rotation slows down decreases.
The increase in the length of a day due to tidal friction is extremely slow. Estimates suggest that a day is lengthening by about 1.8 milliseconds per century. While this may seem insignificant, over millions of years, it results in a noticeable change. For instance, around 620 million years ago, a day on Earth was only about 21.9 hours long.
People often refer to coral reefs as the largest living structures on Earth. Coral polyps form the vast underwater ecosystems by creating calcium carbonate skeletons.
While individual coral polyps are small, they form colonies that can grow and expand over thousands of years. This creates massive, complex structures.
However, it is essential to note that coral reefs, while being among the largest and most diverse ecosystems, are not the largest living structures on Earth. For example, the Great Barrier Reef, which is the most extensive coral reef system globally, is often compared to the size of the Amazon rainforest in terms of ecological importance and diversity.
Coral polyps and photosynthetic algae called zooxanthellae have a symbiotic relationship that makes coral reefs possible. The coral polyps provide a protected environment and nutrients for the algae. Meanwhile, the algae produce oxygen and organic compounds through photosynthesis that the coral polyps use for energy and growth. The growth and expansion of coral reefs depend on factors such as water temperature, light availability, and water clarity.
Over time, the calcium carbonate exoskeletons left behind by dead coral polyps accumulate. This creates intricate structures that provide habitats for a wide variety of marine species. It’s what makes coral reefs some of the most biodiverse ecosystems on the planet. They are often referred to as the “rainforests of the sea.”
The Earth’s interior is not “squishy” in the conventional sense. However, it does consist of layers with varying degrees of solidity and fluidity. Four main layers compose the Earth’s interior: the crust, the mantle, the outer core, and the inner core.
The Earth’s crust is the outermost, solid layer, composed of rocks and minerals. It is the thinnest layer, varying from about 5 km (3 miles) in the oceanic crust to about 30-70 km (19-43 miles) in the continental crust.
The mantle lies beneath the crust and is composed of solid rock, but it behaves like a viscous fluid over long time scales. The mantle is about 2,900 km (1,800 miles) thick and accounts for around 84% of the Earth’s volume. Due to the intense pressure and heat, the rocks in the mantle undergo slow, gradual deformation. This allows them to flow and cause the motion of tectonic plates on the Earth’s surface.
A liquid layer composed mainly of iron and nickel, about 2,200 km (1,367 miles) thick, forms the outer core. The movement of the molten metal in the outer core generates the Earth’s magnetic field through a process called the geodynamo.
The inner core, about 1,220 km (759 miles) in radius, is solid. Primarily composed of iron, it contains smaller amounts of nickel and other elements. The immense pressure at the Earth’s center keeps the inner core solid despite the extremely high temperatures.
While the Earth’s interior is not “squishy” like a soft material, it does have layers that exhibit fluid-like behavior (the mantle) and a liquid layer (the outer core) that contribute to the dynamic processes occurring within our planet.
The Earth is not a perfect sphere, but rather an oblate spheroid. Its rotation causes it to be slightly flattened at the poles and bulging at the equator. The centrifugal force generated by the Earth’s rotation causes the equatorial region to bulge outward. This makes the equatorial diameter slightly larger than the polar diameter.
The difference between the equatorial and polar diameters is not significant when considering the Earth’s overall size. The equatorial diameter is about 12,756 km (7,926 miles), while the polar diameter is approximately 12,714 km (7,900 miles). This difference in diameters results in a shape that is very close to a sphere, but with a slight oblateness.
From a distance, the Earth appears nearly round. People often describe it as “round” or “spherical” in everyday language, which is why. However, for more accurate descriptions, it is essential to consider the oblate spheroidal shape of the Earth.
The Moon is slowly drifting away from the Earth due to the effects of tidal forces resulting from the gravitational interaction between the Earth and the Moon. The process occurs as follows:
The gravitational pull of the Moon creates a tidal bulge in the Earth’s oceans. Due to the Earth’s rotation, this bulge is slightly ahead of the direct line between the Earth and the Moon.
The gravitational attraction between the Moon and the tidal bulge generates a torque that acts against the Earth’s rotation, causing it to slow down. This transfer of angular momentum from the Earth’s rotation to the Moon’s orbit results in the Moon gradually moving to a higher orbit.
As the Moon moves into a higher orbit, its distance from the Earth increases. Currently, the Moon is drifting away at a rate of about 3.8 centimeters (1.5 inches) per year.
The process of the Moon drifting away from the Earth is a natural consequence of the conservation of angular momentum in the Earth-Moon system.
Over time, this drift will continue to occur. It will lead to changes in the Earth-Moon interactions. These include longer days on Earth and a smaller appearance of the Moon in the sky. However, these changes are happening extremely slowly and will take billions of years to have significant effects.
The Earth’s magnetic poles are constantly shifting due to the complex and dynamic processes occurring within the Earth’s outer core. The outer core is a layer of molten iron and nickel that surrounds the solid inner core. The movement of this liquid metal generates electric currents. This in turn create the Earth’s magnetic field through a process called the geodynamo.
The magnetic field is not constant. It varies over time due to the turbulent convection and fluid motions in the outer core. These fluctuations cause the magnetic poles to shift or wander, known as geomagnetic secular variation.
We do not fully understand the exact mechanisms driving the flow of molten metal in the outer core and the resulting variations in the magnetic field. Factors such as heat from the inner core and mantle and the Earth’s rotation influence them.
In addition to the gradual pole shifts, the Earth’s magnetic field can undergo more dramatic changes. These are called geomagnetic reversals, during which the north and south magnetic poles switch places.
These reversals occur irregularly, with the last one happening about 780,000 years ago. The process of a geomagnetic reversal is not fully understood. It is thought to be related to the complex dynamics in the Earth’s outer core.
It is important to note that the shifting of the magnetic poles does not have a significant impact on the Earth’s rotation axis or geographic poles. The magnetic and geographic poles do not align, and their movements are independent of each other.
The driest place on Earth is the Atacama Desert. It is located on the Pacific coast of northern Chile and extending into southern Peru. The Atacama Desert is so dry due to a combination of factors that limit the amount of precipitation it receives:
The Atacama Desert lies between two mountain ranges, the Andes to the east and the Chilean Coastal Range to the west. These mountain ranges block the moisture from both the Pacific Ocean and the Atlantic Ocean, creating a rain shadow effect. As a result, the Atacama receives very little rainfall.
The Humboldt Current, also known as the Peru Current, is a cold ocean current that flows northward along the western coast of South America. This cold current cools the air above it, making it more stable and less likely to rise and form clouds. Consequently, the coastal regions of the Atacama Desert experience less precipitation.
High-pressure systems characterize the latitude at which the Atacama Desert is situated.These promote sinking air and inhibit cloud formation. This stable atmospheric condition further reduces the likelihood of precipitation.
These factors together make the Atacama Desert the driest place on Earth. Some locations receiving less than 1 millimeter (0.04 inches) of rain per year. In fact, there are certain areas within the desert where no rainfall has ever been recorded. People have compared the soil to that of Mars due to its extreme aridity.
A strange thought for you on Earth Day 2023. The hypothesis that Earth may have once appeared purple is based on the idea that ancient microbes might have used retinal, a purple pigment, for photosynthesis instead of chlorophyll, which is responsible for the green color of modern plants. Microbiologist Shiladitya DasSarma proposed the idea, known as the “Purple Earth Hypothesis,” in the early 2000s.
According to this hypothesis, before chlorophyll-based photosynthesis evolved, early microbes called halobacteria used a molecule called retinal for a more primitive form of photosynthesis called retinal-based phototrophy.
Some microorganisms, particularly those in high-salt environments, still use retinal-based phototrophy today. When retinal absorbs light, it appears purple. This led to the idea that Earth’s surface, dominated by these ancient microbes, might have appeared purple.
It is important to note that the Purple Earth Hypothesis is speculative and not widely accepted as a definitive explanation for early Earth’s appearance. There is still much debate among scientists about the dominant photosynthetic pigments during the early stages of life on Earth.
Some researchers suggest that other pigments, such as green and yellow, could have also played a role in early photosynthetic processes. Therefore, we need more research to support or refute the hypothesis, making the idea of a purple Earth intriguing.
Gravity is not exactly the same everywhere on Earth. This is due to several factors that influence the strength of the gravitational force at a given location. These factors include the Earth’s shape, variations in its internal mass distribution, and altitude.
As mentioned earlier, the Earth is not a perfect sphere but an oblate spheroid. It is slightly flattened at the poles and bulging at the equator. Due to this shape, the distance between the Earth’s center and the surface is slightly larger at the equator than at the poles. Since gravitational force decreases with distance, gravity is slightly weaker at the equator than at the poles.
The Earth’s internal mass distribution is not uniform, with variations in the density and composition of rocks and geological structures. These variations cause small local differences in gravity, known as gravitational anomalies. For example, areas with denser rock formations or large underground deposits of minerals can exhibit a stronger gravitational force.
Gravity decreases with increasing distance from the Earth’s center. Consequently, locations at higher altitudes, such as mountain peaks, experience slightly weaker gravity compared to locations at sea level.
While these factors cause variations in gravity across the Earth’s surface, the differences are generally small and not noticeable in everyday life. However, these variations are important for geophysical studies, satellite orbits, and precise measurements in scientific research or engineering projects.
There is a hypothesis suggesting that the Earth might have once had two moons. However, this idea is not widely accepted and remains speculative. The hypothesis, proposed by planetary scientist Erik Asphaug and his colleagues in 2011, posits that a smaller second moon, roughly one-thirtieth the size of our current Moon, formed from the same debris disk created by a giant impact between the early Earth and a Mars-sized body.
According to the hypothesis, long before Earth Day 2023, the two moons shared a similar orbit for millions of years. Eventually, the smaller moon collided with the larger one in a slow, oblique impact. The collision resulted in the smaller moon’s material becoming part of the Moon’s surface. This formed what is now known as the far side of the Moon. Researchers proposed this hypothesis to explain the observed differences between the near and far sides of the Moon, such as the thicker crust and higher elevations on the far side.
However, the two-moon hypothesis remains a subject of debate among scientists. Researchers have proposed alternative explanations to account for the Moon’s asymmetric features. We need more research and lunar exploration to fully understand the history and evolution of the Moon. Until then, the idea of the Earth once having two moons remains a speculative and unproven concept.
The Earth’s largest mountain range is the Mid-Atlantic Ridge, which is an underwater mountain range located in the Atlantic Ocean. The Mid-Atlantic Ridge stretches for about 16,000 kilometers (10,000 miles) from the Arctic Ocean to the Atlantic Ocean near the southern tip of Africa. It is a part of a global mid-ocean ridge system that encircles the Earth for more than 65,000 kilometers (40,000 miles).
The Mid-Atlantic Ridge is formed by the process of seafloor spreading at the boundary between the Eurasian and North American tectonic plates in the North Atlantic and the African and South American plates in the South Atlantic. As these plates move apart, magma from the mantle rises to fill the gap and solidifies. This forms new oceanic crust and creating the underwater mountains that make up the ridge.
Although the Mid-Atlantic Ridge is mostly underwater, some parts of it rise above the ocean’s surface. This forms volcanic islands such as Iceland, the Azores, and Ascension Island. The ridge is an area of significant geological interest due to its role in plate tectonics, seafloor spreading, and the formation of new oceanic crust.
The deepest part of the ocean floor is the Challenger Deep. It is located in the Mariana Trench in the western Pacific Ocean. The Mariana Trench is a crescent-shaped trench in the floor of the western Pacific, east of the Mariana Islands. The Challenger Deep is the lowest point within the trench and holds the record for the greatest ocean depth.
The Challenger Deep has an estimated depth of approximately 10,994 meters (36,070 feet). However, measurements can vary slightly depending on the method and equipment used. This extreme depth makes the Challenger Deep the deepest known point on Earth’s surface. To put it into perspective, if Mount Everest, the highest point on Earth, were placed at the bottom of the Challenger Deep, its peak would still be more than 2,000 meters (6,500 feet) below sea level.
Due to the immense pressure, cold temperatures, and lack of sunlight, the Challenger Deep and the Mariana Trench represent one of the most extreme and least explored environments on our planet. However, scientific expeditions have discovered various organisms adapted to these harsh conditions. These include microorganisms and deep-sea creatures like the snailfish, amphipods, and sea cucumbers.
At one point in Earth’s very early history, our planet had a single, massive continent known as a supercontinent. The most recent and well-known supercontinent is Pangaea. It existed approximately 335-175 million years ago during the late Paleozoic and early Mesozoic eras.
Pangaea was formed through the process of plate tectonics. This phenomenon is the movement of the Earth’s lithosphere (the rigid outer layer of the Earth) on the more fluid asthenosphere below.
The heat and material flow in the Earth’s mantle drive plate tectonics. This causes the lithosphere to move and break into separate plates. These plates can converge, diverge, or slide past each other, leading to the formation of different geological features like mountains, trenches, and volcanic arcs. When several continental plates converge, they can amalgamate into a single landmass, forming a supercontinent.
Pangaea was not the only supercontinent in Earth’s history. Earlier supercontinents include Rodinia (approximately 1.1-0.75 billion years ago) and Nuna (approximately 1.6-1.4 billion years ago). The breakup of Pangaea began around 175 million years ago. At that time, the tectonic plates started to move apart, forming the continents and oceans we know today.
The Earth’s continents continue to move and change due to the ongoing process of plate tectonics. Scientists predict that in the future, hundreds of millions of years from now, another supercontinent may form as the continents once again come together. This cycle of supercontinent formation and breakup has likely occurred several times throughout Earth’s history.
People often refer to trees as “breathing giants” because they play a crucial role in the Earth’s respiratory system. Trees take in carbon dioxide (CO2) and releasing oxygen (O2) through a process called photosynthesis.
During photosynthesis, trees and other plants absorb sunlight, CO2, and water to produce glucose, which is used for energy and growth, and release O2 as a byproduct. This exchange of gases is analogous to the process of breathing, where living organisms inhale oxygen and exhale carbon dioxide.
The term “giants” refers to the large size of many tree species, with some reaching heights of over 100 meters (330 feet). Trees also have an extensive root system that allows them to absorb water and nutrients from the soil, further emphasizing their massive and vital presence in ecosystems.
Trees play a vital role in maintaining the balance of oxygen and carbon dioxide in the atmosphere. They help to combat climate change by sequestering carbon dioxide, reducing the overall concentration of greenhouse gases. Additionally, trees provide habitat for countless species of plants, animals, and microorganisms, making them essential components of ecosystems and biodiversity.
In summary, trees are called “breathing giants” because of their vital role in the Earth’s respiratory system through photosynthesis, their large size, and their significant impact on the environment and ecosystems. On Earth Day 2023, we need trees more than ever.
The largest living organism on Earth is a colony of the honey fungus (Armillaria ostoyae) located in the Malheur National Forest in Oregon, United States.
This fungal colony, also known as the Humongous Fungus, covers an area of approximately 8.9 square kilometers (3.4 square miles) and is estimated to be around 2,400 years old, although some experts believe it could be as old as 8,650 years.
The honey fungus grows underground as a network of thin, thread-like structures called mycelia. These mycelia spread out through the soil and decompose dead and decaying plant material, particularly wood.
The honey fungus can also infect and kill living trees by invading their root systems and extracting nutrients, eventually leading to the tree’s death. While the majority of the fungus remains hidden below ground, it produces visible fruiting bodies (mushrooms) above ground during certain times of the year.
While the honey fungus colony in Oregon holds the title for the largest living organism by area, other contenders for the largest living organism include the blue whale (Balaenoptera musculus) for the largest single animal and the Pando aspen grove in Utah for the largest clonal colony of trees.
Antarctica stores a significant portion of Earth’s freshwater. Approximately 90% of the world’s ice and about 70% of the total freshwater is contained within the Antarctic ice sheet. It covers an area of roughly 14 million square kilometers (5.4 million square miles). The ice sheet is up to 4.8 kilometers (3 miles) thick in some places.
The vast amount of freshwater locked in the Antarctic ice sheet plays a critical role in global climate and sea level. As global temperatures rise due to climate change, the melting of Antarctic ice has the potential to significantly increase sea levels, causing flooding in coastal areas and other related environmental impacts.
It is essential to continue monitoring and studying Antarctica’s ice sheet to better understand the effects of climate change and develop strategies for mitigating potential risks to coastal communities and ecosystems around the world.
The next largest reservoir of freshwater, accounting for about 30.1%, is stored as groundwater in underground aquifers. Groundwater fills the spaces between soil particles and fractured rock beneath the Earth’s surface, forming a crucial source of freshwater for human consumption, agriculture, and industry.
Accessible surface water sources such as lakes, rivers, and swamps contain only a small fraction of Earth’s freshwater, about 1.2%. Despite this small percentage, these surface water bodies play a critical role in providing water for human use, ecosystems, and the water cycle.
It is important to note that the total volume of freshwater on Earth is only about 2.5% of the total volume of water on the planet. The remaining 97.5% is saltwater, primarily found in the oceans, and is not suitable for direct human consumption or agriculture without desalination.
Light from the Sun takes approximately 8 minutes and 20 seconds to travel to Earth. The distance between the Sun and Earth, and the speed of light, determine this time.
The average distance between the Sun and Earth is approximately 93 million miles (150 million kilometers). Scientists call this an astronomical unit (AU). Light travels at an incredible speed of about 299,792 kilometers per second (186,282 miles per second) in a vacuum.
To calculate the time it takes for light to travel from the Sun to Earth, you can divide the distance by the speed of light:
Time = Distance / Speed of light Time = 150 million km / 299,792 km/s ≈ 500 seconds
When converted to minutes, this value is roughly 8.33 minutes, or about 8 minutes and 20 seconds.
Though it may seem like a long time, considering the vast distances in our solar system and the universe, 8 minutes and 20 seconds is relatively fast.
The time it takes for light to reach other planets, stars, and galaxies can be significantly longer, ranging from several minutes to millions of years.
Cosmic dust, which consists of tiny particles of solid matter originating from space, continuously exposes and accumulates on Earth. It comes from various sources, including comets, asteroids, and the debris left behind by the formation and death of stars.
Cosmic dust particles enter Earth’s atmosphere at high speeds, and as they encounter the air, they heat up and can vaporize, creating a bright streak of light known as a meteor or shooting star. While larger particles may create visible meteors, the vast majority of cosmic dust particles are too small to see and simply drift down to Earth’s surface.
It is estimated that Earth accumulates about 40,000 to 100,000 tons of cosmic dust every year. Although this might seem like a large amount, it is negligible compared to Earth’s total mass of approximately 5.97 x 10^24 kg.
Cosmic dust plays a role in various processes, such as the formation of noctilucent clouds at high altitudes, the fertilization of the ocean with minerals, and the study of the early solar system through the analysis of cosmic dust particles collected from Earth’s stratosphere or in ice cores.
Additionally, cosmic dust can provide scientists with valuable information about the composition and evolution of celestial bodies and the interstellar medium.
The total amount of gold dissolved in the Earth’s oceans is difficult to determine precisely due to the vast volume of water and the low concentrations of gold. However, some estimates suggest that there may be around 20 million tons of gold dispersed throughout the ocean.
This estimate is based on the average concentration of gold in seawater, which is approximately 10 to 30 parts per trillion.
Given that the volume of Earth’s oceans is approximately 1.332 billion cubic kilometers (km³) or 1,332,000,000,000,000,000 metric tons of water, even at such low concentrations, the total amount of gold would be substantial.
It is essential to note that despite the large amount of gold theoretically present in the ocean, extracting it is currently not economically viable due to the extremely low concentrations and the technological limitations of gold extraction methods. The cost and energy required to extract gold from seawater far exceed the value of the gold that would be obtained.
Earth’s composition is predominantly made up of four elements: oxygen, silicon, aluminum, and iron. These four elements account for around 87% of the Earth’s mass. Here’s a breakdown of their relative abundance:
These percentages represent the relative abundance of these elements in Earth’s crust, which is the outermost solid shell of the planet. However, the composition of Earth’s mantle and core, located deeper within the planet, differ from that of the crust.
Iron and nickel primarily compose the Earth’s core, while silicate minerals containing elements such as oxygen, silicon, magnesium, and iron mainly compose the mantle.
Even when considering the entire Earth, including the crust, mantle, and core, these four elements still make up the majority of its mass.
Oxygen and silicon, in particular, are the most abundant elements, as they are the primary constituents of silicate minerals, which form the bulk of the Earth’s crust and mantle.
Today, we come together to celebrate the beauty, diversity, and wonder of our incredible planet. Let’s take a moment to appreciate the rich tapestry of life that Earth supports and the natural resources that sustain us.
On this special Earth Day, let us commit to protecting our environment and preserving the Earth’s natural habitats for future generations. By making small, conscious choices in our daily lives, we can contribute to a greener, cleaner, and more sustainable world.
Together, we can make a difference by planting trees, conserving water, reducing waste, and adopting sustainable practices. Every effort counts, and each one of us plays a crucial role in ensuring the health and well-being of our planet.
Let’s cherish our home and work towards a brighter, greener future for all. Happy Earth Day!
Eric Ralls and the entire Earth.com and EarthSnap Team