Outer Space is Closer Than You Might Think.

British spelling.

Outer space is the expanse that exists beyond the Earth's atmosphere and the area between celestial bodies. When we look up at the night sky it appears to be full of stars and other objects, but in reality, almost all of that gargantuan area we call the Universe is empty space, a vacuum.

Sound waves need air, liquids or solids to travel through, therefore space must be a very silent place as sound waves cannot travel in a vacuum.

It is difficult to pinpoint where space begins, an imaginary line named the Karman line is regarded by most experts to be the start of space, that line is just 100 kilometres above the Earth’s surface.

Most of the air in the atmosphere is below the Karman line but there is still a thin atmosphere above, but the farther you travel away from the Earth’s surface the thinner the atmosphere gets.

You might ask, what is the Earth's atmosphere composed of? It is a mixture of different gases and is made up of approximately 78% nitrogen and 21% oxygen. Air also contains small amounts of other gases such as carbon dioxide, neon, and hydrogen.

Even the most diluted parts of the Universe contain a few atoms per square meter, space can also contain different kinds of radiation.

Photo by Norbert Kowalczyk on Unsplash

The ISS, International Space Station orbits the Earth at just over 400 kilometres from its surface. Artificial satellites can be closer to the Earth or much farther away than the ISS.

The average maximum cruising altitude for commercial aircraft is around 13 kilometres, any higher would cause a problem as the atmosphere gets too thin to support large commercial aeroplanes.

Yuri Gagarin was a Soviet pilot and the first human to enter space. That was way back in April 1961. Since that time well over 500 people have made the journey into space. Not very many when you consider that over 100 billion humans have existed, and roughly 8 billion are still alive today.

When we think about the size of outer space, it becomes unimaginable. We can now see objects that are over 13 billion light-years away, the light from that distant objects has been travelling towards us at 1,080 million kilometres per hour for the whole of that vast time.

Photo by Guillermo Ferla on Unsplash

The Universe keeps expanding at an ever-increasing rate, Scientists believe that the Universe is over 90 billion light-years in diameter at this time. Imagine for a moment, it is easy to say 90 billion light-years, but the numbers involved are astronomical.

In one year light will travel 9.46 trillion kilometres, a trillion is 1 followed by 12 zeros. Now multiply 9.46 trillion kilometres by 90 billion that is how wide the Universe is at this time. Yes, it becomes unfathomable.

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We can only imagine what our early ancestors were thinking as they gazed up at the night sky, were they curious as to what the heavens had to hide?

Now it is very different as we have developed sophisticated telescopes and other specialised scientific instruments that are helping to reveal some of the secrets that the Universe holds.

Simple life forms were living on our planet almost 4 billion years ago, since that time billions of animal species have existed, and millions of species are still alive today.

The evolutionary path for life has been long but at last, we have arrived. Our highly developed brain has given us intelligence and curiosity, now we can try and make sense of our existence.

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You might enjoy reading some of my easy-to-understand articles regarding the Universe and Life.

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