The Earth's Fragile Atmosphere

British spelling.

I write easy-to-understand stories regarding the universe and life. here are two of them. Enjoy

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An imaginary line 100 kilometres straight up from the surface of the Earth is regarded as the beginning of space; it is known as the Karman line. Approximately 90% of the atmosphere is below the line.

The farther the atmosphere stretches upwards, the thinner or less dense it gets.

The atmosphere surrounding the Earth contains all the gases retained by the Earth's gravity. It is what we breathe; it keeps us alive.

The atmosphere is important for so many reasons. That layer of gas protects us and all other species from the heat and radiation emanating from the sun.

Photo by CHUTTERSNAP on Unsplash.

21% of the atmosphere is composed of oxygen, which is crucial for almost all the life on Earth. The other elements are 78% nitrogen, 0.93% argon, 0.04% carbon dioxide, and trace amounts of other elements. It also contains a large amount of water vapour.

One estimate for all the water the atmosphere can hold at any one time is almost 13,000 cubic kilometres. A cubic kilometre holds one trillion litres of water, which is 1,000,000,000,000. So it's not surprising we witness flooding in many parts of the world.

Weather describes the state of the atmosphere at certain times and places. Temperature, moisture, clouds, and wind strength are directly involved in weather.

Extreme weather conditions can be described as hurricanes, tornadoes, floods, tropical storms, and lightning strikes, to name a few.

Photo by Nikolas Noonan on Unsplash.

We humans are endangering our life-giving atmosphere. Roughly 8 billion people are alive at this time, all of whom are contributing in one way or another to the pollution that is poisoning our beautiful world.

When are we going to correct it before it's too late?

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A supernova is a colossal explosion of a star

The image below shows Cassiopeia A, the remnant of a supernova explosion, which can happen when massive stars end their lives. This remnant lies 11,000 light-years from the Earth.

Image credit: NASA/CXC/SAO.

One light-year is equivalent to 9.46 trillion kilometres.

A trillion is 1 followed by 12 zeros.

The colours in the image distinguish different elements that the original star and the supernova created.

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A type 1 supernova occurs in binary star systems when two stars orbit around the same point, the barycentre.

If one of the stars, a white dwarf, is close enough, it can gather matter from its companion star. Eventually, the white dwarf star accumulates so much matter and becomes so dense and unstable that it explodes, resulting in a type 1 supernova explosion, destroying the whole star.

The most recent supernova that took place outside our galaxy and could be seen with unaided vision was a type 11 supernova named SN1987A.

Its light arrived on Earth in February 1987. It is approximately 168,000 light-years away.

A much closer supernova event in our galaxy, the Milky Way, was SN 1604, or Kepler's supernova. Although it was 20,000 light-years away, it shone brighter than any other star in the night sky. It was first seen on October 9, 1604.

A low estimate for the number of stars in our galaxy is 100 billion; a higher estimate puts the number at 400 billion, but on average, a supernova will occur only one or two times each century in the Milky Way.

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A type 11 supernova occurs when a single high-mass star runs out of fuel, and as a result, some of its mass moves into its core. The core gets so heavy that it can't withstand the gravitational force and collapses, resulting in a giant supernova explosion that is so bright that it can briefly outshine the whole galaxy.

Depending on the mass of a star, a neutron star or black hole can be left behind after a type 11 supernova explosion.

Stars create elements in their cores by nuclear fusion, which starts with fusing hydrogen into helium. Some larger stars can create every element up to iron, but iron is the heaviest element a star will create using fusion.

Elements heavier than iron are created in supernova and kilonova explosions. When stars come to the end of their lives, many different elements are ejected far into space.

Sometime in the future, these new elements will become part of stars, planets, or some other celestial objects; they might end up being part of some extraterrestrial life form somewhere in that vast area we call the universe.

Image by WikiImages from Pixabay.

Our local star, the Sun, will have a more peaceful end; it is roughly 4.6 billion years old and is estimated to be halfway through its element-producing life.

When the sun runs out of fuel, it will eventually end up as a white dwarf star, but far into the future, it will evolve into a black dwarf star when it ceases to emit any light or heat. That long cooling process could take as long as a quadrillion years.

The end.

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