Once believed to be in the center of the universe, our Earth remains the only planet known to harbor life. According to radiometric and other sorts of evidences, the Earth was formed more than 4 billion years ago. Within the first billion years after its formation, few simple forms of life appeared on the Earth’s surface and the rest is history. I am sure you know a load of things about the mother Earth, but are you sure you know everything? Here are 15 facts about the planet Earth that you may not know.
Equatorial Diameter: 12,756 km
Polar Diameter: 12,714 km
Mass: 5.9×1024 kg
Surface Temperature: -88 to 58°C
Surface Gravity: 9.807 m/s2
Natural Satellite: Moon
15. Earth is Not Named After any God
The central figure of this Ara Pacis is the mother goddess or Earth.
After discovering several planets in our solar system, ancient Romans named them after their Gods, these planets are Mercury (god of commerce), Venus (god of beauty), Mars (god of war) and two of the biggest planets Jupiter (god of sky and thunder) and Saturn (god of wealth and agriculture). Their equivalents are also found in other ancient cultures.
When Uranus and Neptune were discovered with the help of modern telescopes, scientists were generous enough to name them after other Roman Gods. In fact, Pluto, which is currently not classified as a planet is named after the Roman god of the underworld. Although the Earth is not directly named after any Roman god, it is closely associated with the Tellus Mater or Terra.
14. A year on Earth isn’t 365 days to be Exact
No, the correct answer is 365.2564 days. Do you ever wonder why calendars have a Leap year after every 4 years? It’s because of that extra 0.2564 days. It’s just a simple math, where we balance the 0.2546 days by putting it as an extra day in the month of February after every four years. But this rule is not applicable when the year is divisible by 100 (but not by 400).
13. True Earth Day
Long-exposure photograph showing the paths of the stars relative to the Earth
The Earth takes exactly 23 hours, 56 minutes and 4 seconds to rotate once on its axis, which astronomers called a Sidereal day. So does that mean an Earth day is about 4 minutes shorter than we think? Well, this is not the case here. A Sidereal day tells us how long the Earth makes one rotation relative to the distant fixed stars in the sky.
So, if you keep a note of a star above your location in the midnight, you will find out that the same star will appear at the same position again after 23 hrs, 56 minutes and 4 seconds. But we measure time on Earth in accordance to Sun and not by a distant star. Our planet takes about 365.25 sidereal days to complete a revolution around the Sun, however, that distant star would have appeared on the same spot about 366.25 times by now.
So if one sidereal day is 23 hours, 56 minutes and 4 seconds or about 86164 seconds, multiplying this by 366.25 sidereal days gives us 31557565 seconds, dividing it by 365.25 days gives us 86,400 seconds or exactly 24 hours, one Earth day.
12. It is the Most Densest Plant in Our Solar System
Cutaway diagram of Earth’s internal structure
As we all know that four of the biggest planets in our solar system is mainly composed of gas and are the least dense plants in our solar system. Planet Mars, have a mean density of 3.93g/cm³ and it is the fifth least developed planet in our solar system. The remaining three planets have somewhat identical densities with Earth’s slightly higher at 5.514 g/cm3.
The density of Earth varies too. Earth’s inner core is perhaps its densest region, followed by the outer core, then the mantle and finally the crust (least dense).
11. Earth’s Magnetic Field
Computer simulation of the Earth’s field
Earth has a pretty strong magnetic field and it is the only reason humans and all the living organisms are safe from the deadly solar radiation. Do you know how Earth’s magnetic field is created? Like the most of the planets in our solar system, Earth’s magnetic field also arises from its core, except for the planet Venus which do not have any significant magnetic field.
10. Earth is Mostly Composed of Oxygen, Iron, and Silicon
Our Earth is like a messed up refrigerator with many materials inside it and we have to sort things up. After separating materials, we would get about 32.1% of iron, 30.1% oxygen, 15.1% silicon, 13.9% magnesium, 2.9% sulfur and other elements in trace amounts.
9. Earth’s Atmosphere is Extended Up to 10,000 km
The exosphere is the outermost atmospheric layer on Earth, extending from thermopause or exobase at about 700 km to the outer reaches of the Earth’s atmosphere where it meets solar wind at 10,000 km above sea level. Exosphere is largely composed of helium and hydrogen, while nitrogen and carbon dioxide is present near the exobase. And yes, most of the Earth’s satellites are stationed here.
A fun fact, planet Mercury and large moons in our solar system such as the Galilean satellites and the Moon have exospheres without a denser atmosphere below which are known as surface boundary exosphere.
8. From Tallest to the deepest
Mauna Kea from the ocean
Do you know that Hawaii’s mount Mauna Kea, a dormant volcano is the 11th tallest mountain in the solar system (based on base to peak height). While most of Mauna Kea is underwater, its total height when measured from base to tip is more than 10,000 m, thus it’s the tallest mountain on the Earth.
The deepest point on the planet is the Challenger Deep, which is about 11 km deep and is located in the Marina Trench, western Pacific ocean. It was discovered for the first time during the 1870s by the HMS Challenger. Since then only two expeditions of the deep are successfully completed.
7. Earth’s Shape
Do you know Earth is geoid and not round? Well, yes. A geoid is basically a mathematical approximation of how a real Earth would look like under the influence of gravity and other phenomenon such as rotation on its own axis.
6. Earth’s Rotation is Slowing Down
Earth’s unique rotation plays an important role in making the planet habitable for the humans. Change in rotational speed would drastically affect weather pattern, day and night time, and wave rhythm in the ocean. Multiple analysis of historical astrophysical records indicate that the Earth’s rotation is indeed slowing down at a rate of 2.3 milliseconds in a hundred years or so. The earth’s rotation is gradually slowing with time; therefore, day-time were used to be shorter in the past. This is due to the tidal effects the Moon has on Earth’s rotation.
5. Earth’s Co-Orbital Satellites
Cruithne appears to make a bean-shaped orbit from the perspective of Earth.
Unlike the gas giants and Mars, Earth has only one natural satellite, the moon. But do you know there are at least one asteroids locked into co-orbital orbits with Earth? The asteroid designated as 3753 Cruithne is an about 5 km wide and orbits around the Sun in a bean-shaped orbit. Although it doesn’t orbit around the Earth, its relative path from Earth perspective around the Sun makes it look like it’s following the Earth.
4. Water in Earth’s Mantle
Recently, a team of scientists from Germany and Japan discovered strong evidence of large quantities of water present in the Earth’s mantle. For several years, Earth’s mantle has been the center of many scientific debates. The water level in the upper and lower part of the mantle is almost next to none and researchers were able to confirm it by examining the material present in those layers.
But many suggest that in the middle layer of mantle, a huge amount of water might be present in a different form due to the presence of minerals like wadsleyite and ringwoodite which have a high water carrying capacity. After carrying a series of test and lab simulations, including synthetic ringwoodite, researchers were able to infer that those waterlogged minerals in the middle mantle might have water almost equal to the amount of water present in the oceans.
Journal Source: DOI: 10.1126/sciadv.1603024
3. The Beauty of Plate Tectonics
Motions of plates based on GPS (Global Positioning System)
The plate tectonics theory is currently the best possible scientific theory to explain the large-scale movements of the continents throughout the course of human history. This model is based on the famous continental drift theory and it was accepted by the community for the first time after seafloor spreading was detected in the 1950s.
In our solar system, the phenomena of plate tectonics is only evident on the Earth, although new signs of plate tectonics on the planet Mars have been discovered by researchers recently. Plate tectonics is basically the upper layer or the crust, floating above the asthenosphere. The plate tectonics is the reason why we have frequent earthquakes in Japan, active volcanic activity near the ring of fire and rigorous mountain building activities (Himalayas).
2. Uneven Gravity on Earth
Gravity anomaly map from NASA’s GRACE satellite
In the 1960s, researchers discovered an anti-gravity zone surrounding the Hudson Bay, Canada, where the effect of gravity is much lower than any other place on this planet. After years of studies, scientists have concluded that lack of land mass due to enormous glaciers in the past beneath this region, is one of the major reasons behind this uneven gravity.
In the year 2002, NASA sent their GRACE satellite to measure Earth’s gravity fields and detect anomalies. With the help of GRACE’s data, researchers were able to illustrate how the mass is distributed over the entire Earth and how it varies over time.
1. The Future and Beyond
This is Earth may look like 7 billion years from now/ Image Courtesy: Fsgregs
According to the modern stellar theory, our Sun will inflate and become a red giant in about 5-6 billion years. During that phase, its luminosity will increase 10% in 1 billion years to 40% in 3.5 billion years. This increase in heat will intensify the rate of the inorganic CO2 cycle, which will reduce its availability for plants for photosynthesis and ultimately lead to the extinction of plants.
Without plants and vegetation, the Earth will start to lose oxygen and human life we know on this planet will become extinct too. After another few million years, the global temperature will touch almost 70 °C, and water from every corner of the world will be evaporated. Researchers have estimated that life should be feasible on the Earth until the next 500 million years or so without any external factor.