Earth is currently the only planet known to support life, and large radio dishes are actively searching distant stars for signs of alien life.
Yet there is so much more to discover about this extraordinary planet we call home. Here are 10 intriguing facts about Earth to help get your learning underway.
1. The Earth is an oblate spheroid
Isaac Newton was the first to suggest that Earth wasn’t perfectly round. He suggested it was more accurately an oblate spheroid, a sphere with squashed poles and bulging at its equator; due to this bulge in its center-to-sea-level distance at both poles than at the equator.
The Earth’s oblate shape is caused by centrifugal force, which happens when its mass spins faster at its equator than at its poles. This results in its mass bulging outward at the equator – similar to how pizza dough expands outward when baked – causing its radius at the equator to be approximately 21 kilometers (13 miles) larger than at its poles.
Humans living on Earth do not perceive this change to their gravitational pull as being problematic; however, small variations are detected by satellites orbiting Earth to form Earth’s magnetic field and deflect harmful charged particles from space.
Scientists have also discovered that the Earth’s oblate shape has significant ramifications for its evolution and formation. For instance, the thicker polar regions contain more iron and other metals which slow magma from rising from its base into volcanoes, thus decreasing their likelihood.
The Earth is also an oblate shape, which has an enormous impact on ocean currents, making its shape essential when planning ship routes or aircraft flight trajectories. Furthermore, this influencer of light refraction at its boundary between air and surface also plays a part in how we see color in our skies.
Scientists only recently realized the full effects of Earth’s oblate shape on its planet, such as how it affects microbial life found at depths not previously thought possible. One particularly remarkable instance is how its gravity has allowed life forms such as bacteria to flourish in depths never imagined before by humankind.
2. 70% of the Earth is water
Earth is widely recognized as the Blue Planet due to its abundance of liquid water, which allows life on our planet and gives it its signature blue hue from space. Most of this liquid exists within oceans which cover 70% of Earth’s surface; however, water can also be found in glaciers and ice caps, rivers, lakes, groundwater supplies and soil moisture as well as air as vapor – hence earning this nickname.
Though water comprises only approximately 0.05 percent of Earth’s total mass, it is an integral component of life on our planet. Water was instrumental in the emergence of first living organisms as well as in shaping Earth’s ecosystem; additionally it enabled abiogenesis – the process whereby nonliving matter becomes lifeforms – through which lifeforms were produced from non-living matter.
Researchers recently made the surprising discovery that water, covering 71% of Earth today, may have arrived earlier than previously believed by studying hydrogen isotope ratios in seawater samples. By comparing the ratios of these isotopes in the ocean with those found in atmospheric hydrogen and deuterium levels, scientists were able to calculate how much hydrogen had been lost over time due to space travel. These studies allowed scientists to estimate how much deuterium (a light hydrogen isotope) had been converted to heavy water during Earth’s early history through methanogenesis processes, explaining why heavier hydrogen isotopes now make up less of the oceans than they once did.
Scientists have also determined that Earth’s magnetic field is generated by an ocean of liquid metal swirling around its solid iron core, producing electric currents which generate magnetic fields visible on Earth’s surface.
Earth’s water is not only essential to life on the planet, but has also allowed scientists to gain a better understanding of our solar system’s formation. Recent research suggests that water may exist within most planets’ rocks – and therefore more “blue planets,” or planets with plenty of liquid water are more likely to exist than we ever imagined before.
3. The Earth is a sphere
People have long held the view that Earth was flat; however, some skeptics pointed out its shape could not possibly be round due to gravity’s effects being dependent upon distance between objects rather than on any one point. Yet that assertion did not hold up against evidence and therefore the idea that the Earth is round became prevalent.
Geodesy has long confirmed the Earth is round due to GPS and other technologies for measuring its size and shape, and images taken from space show that its surface is indeed round.
Spherical models of Earth provide the most useful approximations for most purposes, including geography, astronomy and navigation. While more accurate models like geoid and ellipsoid exist (the latter of which being more frequently utilized), most practitioners still rely on this spherical representation.
One of the primary advantages of having a round planet like Earth is that we can observe more of its surface than if the world were flat, such as oceans, mountains, valleys and other features being more easily visible from various points across its surface. Furthermore, having nightfall in one part while daybreak occurs elsewhere also highlights its round nature.
Another evidence that Earth is round comes from studying the shadow of the Moon during an eclipse. No matter whether it occurs during day or nighttime, its shape remains circular whereas on a flat Earth the shadow would take the form of a line.
Its shape also makes navigating easier: we would need compasses to point towards our destination on a flat Earth; otherwise, it would be impossible for us to know when we were getting closer. With a sphere Earth however, all it would take is following our compass’ needle until we reached where we wanted.
4. The Earth is an ellipsoid
While the Earth may appear spherical in photographs, its shape is actually that of an ellipsoid. Widest at its equator and narrowing towards its poles. Due to differences in density of materials that make up its composition (which makes stiffer objects than fluids), its surface gravity does not remain evenly distributed across its surface area. Regional factors may also play a part; one such regional factor being rebounding of crust after very thick glaciers melted previously.
Therefore, Earth’s ellipsoid is commonly known as a geoid; its geometry defined by both gravitational and centrifugal forces. Geoids serve many functions from estimating sea level estimates to plotting GPS coordinates or flight paths and even being an essential tool in conducting planetary surveys.
An observer in space may see Earth as a perfect sphere, but that’s only because they’re looking down from above. From space, however, Earth appears flattened compared to when seen from below because its radius for the polar semi-axis is shorter than that for its equatorial semi-axis.
Scientists use mathematical formulae to model Earth’s true ellipsoidal shape by creating a reference ellipsoid, though this model’s flattening may vary slightly between surveys due to measurement methods or whether its aim is to model all or only certain regions.
Other fascinating facts about Earth include its magnetic field, which is generated by rapid rotation and its nickel-iron core. This field protects it from solar wind and cosmic rays from space, while tilt of Earth’s axis varies over time due to Jupiter and Saturn’s gravitational influences at regular intervals affecting climate and ocean currents; its effects have had significant contributions towards recent temperature shifts on planet.