The Earth: Our Little Blue Oasis
And in one special place, far from all that we know;
we found ourselves a place, that we could call home.
Our Earth. It is such a special place. There are many other planets in the Universe, just unfathomable trillions of them. And despite that, almost none of them look like Earth. And for so much of its history, Earth looked so different. But over time, it has evolved into a truly unique life support system for its creatures, protecting them from the harsh and indifferent ravages of space. And humans seem to mostly take it for granted, or even try and destroy it. We should appreciate her more. Let’s dive in, to our Earth.
Our Earth: Why it’s so special
There are a lot of planets out there. Estimating how many galaxies, stars, or planets there are in the Universe is a bit of a foolish pursuit – it’s just so many and seems to go up every time we try. There’s a huge variety of star systems out there, some with no planets around any of the stars, some with hundreds of planets around a single star. There are also weird things called rogue planets that are just deep off in space on their own, away from any stars – billions of them, maybe even outnumbering the number of stars. So it’s probably hundreds of trillions.
NASA has been keeping an ‘Exoplanet Archive’ of planets that are sufficiently similar to Earth that they may have a similar life. Of the hundreds of thousands of planets we’ve observed in enough detail to learn about them, only about 5,000 of them are considered seriously similar to the Earth (and that’s being generous). Earth is so special and different from every single other planet we have ever seen. Why?
The main things that make our Earth so special are its temperature, atmosphere, water, and it’s magnetic field.
The sun on our face: Earth’s temperature
One of the most obvious things that is special about Earth, is our temperature. On Earth, the temperature is great. It’s not too hot and not too cold. It is also very consistent compared to other planets. Between an Earth day and Earth night it generally only varies by about 30 degrees celsius. There isn’t that much of a difference between summer and winter either.
This is very unusual for a planet and makes Earth much better for life. For instance, Mars, the closest planet to Earth, goes from 20 degrees celsius to -73 at night. It’s difficult to imagine life evolving in such conditions. Life that specialized in surviving hot temperatures would die during the freezing nights, and life that could manage in cold temperatures would be roasted alive during the day.
The Earth’s temperature is so consistent because of the way the Earth orbits the sun and the way it spins. Firstly, the Earth stays a very consistent distance from the sun in its orbit, it’s a very neat circle. Any planet that’s orbit is a bit more like an egg, is going to vary a lot in temperature. Secondly, Earth spins around its own axis, which gives us days and nights. And those days and nights are nice and short, if they were too long one side of the planet would be much hotter than the other and all sorts of weird things would happen.
Thirdly, the Earth is on a bit of an angle to the Sun, it’s a bit “tilted”. This means that for half of the Earth’s orbit, more sun hits “the top” of the Earth, and for the other half, more sun hits “the bottom”. This is what gives us our seasons. But the tilt isn’t that bit (only 23 degrees) so the difference in seasons isn’t that much – enough to give us some variation, so to create some different environments, but not too much to make that variation so extreme that nothing can survive both a summer and a winter.
The water we drink: Earth’s water
Liquid water is the core of all life on Earth. Water has a few magical properties that very few other substances have. Firstly, water can dissolve and carry almost any other chemical – and this is super important for life, as it can carry nutrients around an organism (think blood in animals). Water is transparent, meaning light can get through it into cells to provide energy to allow chemical reactions to occur (particularly in the ocean). Water can also exist in all three states at very similar temperatures (solid – ice at the poles, liquid – oceans, and gas – the atmosphere). This means you can have big complex systems like the water cycle, where water changes state and helps the Earth regulate its temperature. Water is very dense, so it can hold a lot of heat and mass, and most weirdly, solid water is less dense than liquid water, meaning icebergs float!
The development of water on earth is still a bit of a mystery. Obviously early on, when the Earth was in its troubled teenage phase (see our post), it was too hot for there to be a lot of water. Once it cooled down, some of the hydrogen and oxygen in the rocks that formed the earth began to evaporate and combine into water.
However, there is also another potential source of water. There is a lot of hydrogen in the Universe, and a bit of oxygen, and when these things exist together, they tend to combine pretty readily to make water (basically always frozen in deep space). So some water on Earth probably came from some interstellar sources like comets. Exactly how much water came from comets and how much from the Earth itself is not really understood.
The air we breath: Earth’s atmosphere
The first atmosphere of the Earth, 4 billion years ago, was just leftover gas from the Early solar system. The atmosphere would mainly have been water vapor, hydrogen, and ammonia and would have been very thin, similar to the outer areas of Jupiter and Saturn today. However, it was lost into space very quickly. This was because the Earth’s magnetic field had not yet formed, to protect it from solar winds keeping its atmosphere by shielding it from solar storms.
The first proper atmosphere of the Earth (known as the second atmosphere) was created by volcanoes. The volcanoes caused by the extreme heat and geological activity on Earth earth spewed out enormous amounts of gas around the planet. This was mainly nitrogen, carbon dioxide, and other gases, but almost no oxygen.
Oxygen came into the Earth’s atmosphere much later. It was actually produced by the first early lifeforms on Earth, as opposed to created geologically. We can see exactly when this happened because they fundamentally changed the geology of the Earth (we talk a lot more about this here).
Earth: We need to be kinder
It’s seen as a bit of a new age, hippie or weird thing to feel some form of emotional connection to the Earth. As if respect for the planet we live on, is somehow weird, immature, or effeminate.
We can make up lots of theories about how many Earth-like planets might be out there in the Universe. We’ve come up with lots of models over the years, estimating how likely a planet is to develop water and be at the right temperature. Some of these models might even be right. But the simple fact is, we have never seen another planet even vaguely like our Earth. It is perfect. The perfect temperature, made of the right stuff, in a perfect place. And it didn’t start out as perfect, it’s gone through so much to get there, starting as a noxious fiery hellscape. But now it is the perfect blue oasis of our Universe.
We should be so grateful for the Earth. And we really don’t act like it. The human species, even from its very earliest days has massively affected the planet. We are going to talk about this a lot more on The Universal Story (see here). Even with the rising consciousness of environmentalism, frankly, most people are still nowhere close to appreciating how much we’ve changed the planet since we evolved. The Earth’s done so much to resist it and to recover, which so few of us see. Maybe the first steps are to appreciate how unique the Earth is. And how lost we would be without her.
