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Word Art: Earth [Astronomy Series]

We don’t spend much time thinking about Earth being as much an astronomical body as any other planet in space, and I said as much in the text.  This one was both easier and harder than the other planets because of that.

Earth

Earth

We live here.

The most thoroughly explored planet in the Solar System, as little as we spend time thinking of it as one.

Formed, as the other planets were, from the solar nebula, accreting over tens of millions of years or so.

The crust was a molten mass until enough water begin to form to cool it down to solidity.

Water vapor, along with ice from asteroids and proto-planets which collided in the primordial times, led to the formation of the oceans that cover most of the surface now.

This is the only planet we know of with liquid water on it.

Any other place in the solar system where we suspect water might be found, it is to be found in the form of ice.

Most of the fresh water on the surface of this planet is also in the form of ice.

The oceans are salted with volcanic emissions.

They also form a reservoir of gases that sustain an abundance of life.

The average depths of the oceans are more than 4 times the average height of the dry land continents.

These oceans are kept unfrozen by the heat held in by the atmosphere.

The life on this surface has changed the atmosphere over time. (It continues to do so.)

Photosynthesis which evolved some 2.7 billion years ago, poured oxygen into what we now call the air, and thus were life forms that depend upon this oxygen able to evolve.

The flood of oxygen also led to the ozone layer which helps deflect the ultraviolet solar radiation, along with the magnetic field.

The gradual leak of hydrogen out into the void allowed the remaining oxygen to flow freely instead of being bound up as water.

These days most of the hydrogen gets turned into the H in H20, but hydrogen still exists in the atmosphere as the change of methane occurs.

Water evaporates, condenses and then comes back down to the surface in the form of precipitation.

The water flows to the oceans and lakes through a system of rivers and this cycle is essential to life on Earth.

The atmosphere also keeps the heat in and keeps bits of rock from space from marring the surface, the way they do on so many other planets in the solar system.

Large enough ones can still make an impact at times, though.

It appears that one extremely large impact in the far distant past was enough to form our Moon, as it struck the Earth with enough force to send a chunk of mass into space.

That impact may also be the reason this planet tilts so, which gives us the seasons.

The tilt is such that the lower portion of the planet winds up closer than the upper to the sun as the orbit puts the planet a little bit nearer during the southern hemespheric [sic] summertime.

Fortunately, there are more oceans and less land on that part of the planet so the heat is absorbed by the waters.

(We do have much to thank water for on this planet.)

The magnetic field of Earth is the strongest of any planet that we know of.

It appears to be a result of the heat of the molten outer core generating electricity which in turn creates magnetism.

The field forms a magnetosphere strong enough to deflect the solar wind and this keeps the atmosphere intact.

The exact locations of the magnetic poles are prone to wander from year to year and the field shows signs of having reversed completely, the last such reversal having happened about 780,000 years ago.

(Are we due for another? What a mess it would be if it did right about now.)

Even as hospitable a planet as this only has an eighth of its surface as habitable for creatures such as us.

Three quarters of the surface is submerged in ocean water, and of the dry land that does appear, a little over a quarter of it is mountains too high for us to occupy and another tenth and change is desert.

Two hundred and one nations each claim their portion of the land and the sea.

No one nation has ever ruled all of it, though some have tried (and failed.)

And yet we still strive for the day when we crazy humans will see that our commonalities outweigh our differences and learn to take the best possible care of this fragile biosphere in its precious uniqueness.

I could do it in no other color than blue.  It is the only planet I did in blue, understandably.  Alas, my Nice Light Blue Pen got lost in a bar somewhere when I was working out in the world and I had to use an imperfect substitute for this piece.  It seemed to have sufficed.

Prints of this work are available here.

The original is not for sale.

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