Why do scientists consider Earth unique even in 2021? Well of course, because it’s the home of so many varieties of life forms and also home to the most complex being we know of to date: humans!
Seriously, there are several important features that make Earth a unique planet.
Let’s go over a few of them.
The Goldilocks zone.
Earth is the third planet from the Sun and, until now, is the only one known to harbor life. Its location in the solar system is strategic because it contains water in liquid form on its surface. Earth is in what is called the Goldilocks zone, meaning not too far from the sun for all the water to freeze solid and not too close that the water would be vaporized.
We believe through radiometric dating that our planet is about 4.5 billion years old.
Earth is the densest and largest solid planet in our solar system. 71% of its surface is covered in water and 29% is covered by land. Scientists tell us that most of the water on Earth came from ice from asteroids and meteors which hit Earth in its early history. Hard to believe, isn’t it?
About 4 billion years ago, a chemical reaction produced complex molecules which mingled together and started to multiply, and life was born. At the beginning, Earth had very little oxygen in its atmosphere. Indeed, the gases present at that time, nitrogen, carbon dioxide, and methane, would be deadly to us today.
Unicellular organisms evolved into multicellular organisms. Photosynthesis appeared and living cells started to produce oxygen in large quantities. The interaction between oxygen molecules and ultraviolet radiation from the Sun led to the formation of the ozone layer. This protective layer in the atmosphere is extremely important because it protects all life on Earth from damaging radiation from the Sun. That’s why, even if there was enough oxygen on Mars to breathe comfortably, the lack of the protective ozone layer means we would die from radiation exposure.
Earth’s central core is made primarily of liquid iron and a few other metals like nickel. Mars doesn’t have a liquid core but Jupiter and Saturn also have one. The core rotates with the rotation of the planet and produces convection currents and an electromagnetic field. Earth, Jupiter, and Saturn possess this field which extends far out in space like a bubble and protects the planet from deadly ionized particles from the Sun. Those ionized particles, mostly electrons, shine when ionized and produce the Aurora Borealis and Australis.
The continents are located on the surface of what are call the tectonic plates. These formations float above the liquid core of the planet and their movements, caused by the convection currents of the central core, produce volcanic activity, earthquakes, and mountain ranges like the Himalayans, the Rocky Mountains, the Andes, etc. There is a constant remodeling of the planet’s surface because of them. As far as we know, no other planet has tectonic plates.
Four billion years ago, a massive object the size of planet Mars collided with a young Earth. The collision sent millions of particles in space which bound together and created the Moon. At the time, the Moon was much closer to Earth than it is now, about 80,000 miles instead of 238,000 miles. At the time, it had a magnetic field and shared it with Earth. This enabled the Moon to act as a protective barrier against the solar wind and the young Sun’s powerful radiation. The Moon was critical in Earth’s ability to keep its thin atmosphere and protect emerging life during this vulnerable time.
In 1687, Sir Isaac Newton explained that ocean tides are created by the gravitational pull of the Moon. There are two high tides and two low tides every 24 hours. Apart from the obvious high and low of the water, there is another important consequence to the tides. Life had to develop ways to live in the water and on dry land. This encouraged changes in physiology and the development of lungs in creatures which eventually were able to live on land.
Finally, the Moon is relatively large compared to other moons in our solar system and it helps to stabilize Earth’s axis and acts as a shield against passing asteroids and comets.
Earth is fortunate to live in a good neighborhood. Our Sun, at 4.6 billion years old, is still young and this is important because this immense furnace will remain stable for a long time. Indded, the Sun still has about 10 billion years to live. The only problem is that we believe its brightness will increase by 10% every billion years and this will eventually destroy all life on Earth. This means our lease will be up in less than 1 billion years!
Space exploration is in infancy, but we must search for Earth-like planets if we want to survive as a species. Until then, life will continue as usual if we take good care of our planet!
Our close neighbor the Moon is good to us and continues to protect us from being hit by asteroids and other space debris. Our biggest neighbor, planet Jupiter, is also a good neighbor because being so large, its gravity attracts a lot of large rocks, asteroids, etc. and it gets hit instead of us. Some think Earth would not have survived without the protective influence of Jupiter.
On Earth day, April 22nd, celebrate and contribute to keep your planet beautiful. Remember Earth is unique and precious. Each one of us needs to be mindful of its fragility and help take care of it because we will never find another one like it.
Enjoy Earth, your own little planet! Live long and thrive!
Cami is a retired physician who loves astronomy and science-fiction and fantasy. She published her first novel, a sci-fi romance, I Am Sheffrou, An Alien Love Story, Book 1 of The Sheffrou Trilogy, in July 2020. She is actively working on Book 2, Betrayal, The Color of Treason.
Sources: NASA, NOAA, Wikipedia, and http://www.Inverse.com.