There are some moments in our life where we see something so magical that the memory is affixed in our brain for years. For me, one of those moments was to do with the night sky. I was alone in the countryside in a tent and happened to look up.
At that moment, I saw the complete night sky without the light pollution of the city, not just a few stars or the moon, but the whole map of the constellations. It was, truly, magical, and I doubt I will forget it.
However, when we look at the sky in the day, we see possibly a cloud or two, some clear blue patches, and the giant glowing orb that is our sun. We don’t tend to see anything else until night comes again. But perhaps you looked up at the midday sky and wondered about the sun.
Maybe you questioned what it was and what its relation is to us on earth. Is it a planet? Or is it a star? Today, we seek to provide the answers to these questions and give you a concrete knowledge of what our sun really is.
What Is A Planet?
First, we will start by answering an age-old question that is still hotly debated today. What is a planet? Well, a planet is an astronomical or celestial body that orbits a star or a stellar remnant.
What this means is that a planet needs to exist in space and follow a circular pattern around a star with little to no chance of dramatically changing this pattern, as such it will not go outside the star’s gravitational pull.
This isn’t the only criteria that a body in space needs to clear before being declared a planet, though, as that would make some comets planets in their own right.
One other thing a planet needs is a precise level of gravity affecting it. The body needs to be big enough to have its own gravity impact it to the point where it becomes circular and rounded, however, it also cannot be too large or it will cause thermonuclear fusion, the same kind of fusion in stars and nuclear bombs.
The International Astronomical Union has one other criterion for defining planets, and that is it has “cleared its neighborhood”, so to speak. This means that the planet is the dominant gravitational body in its orbit and has no other celestial bodies around it of similar size. It should only have satellites or small objects orbiting it.
A great example of this is the moon of our earth, it is nowhere near as large or as gravitationally dominant as the earth and is held in place by the earth’s gravity.
Any planets that don’t clear this final hurdle are known as dwarf planets. There is only one dwarf planet in our solar system currently, which is Pluto as it intersects with the orbit of Neptune, a much larger planet.
This final piece of criteria is subject to debate and has been for many years – when I was younger, Pluto used to be a full planet! – so it might be best to use the first two criteria to define a planet while using the final one as a backup.
What Is A Star?
A star is another astronomical body in our universe, however, they are far, far larger than planets and burn very brightly.
To give you an example of how massive they can become, we can see stars from other galaxies and the planets of our solar system in our night sky, but they look very similar in shape and size despite the vast distance between them.
The light reflected off the planets that make up our solar system is seen on the same night it is reflected, however, the stars of other galaxies are so far away that the light was produced by that star thousands of years ago, it just takes thousands of years to reach our solar system.
A star’s life begins when a gaseous nebula – interstellar clouds composed of huge deposits of different molecules – that is mostly hydrogen, helium, and some other heavier elements experience a gravitational collapse.
This causes the nebula to contract and pull all this material inwards, which in turn sparks thermonuclear fusion and creates a star.
The total mass pulled into the star, at the beginning of its life, determines its life span and size. After the dust has settled, the star will shine and produce energy, thanks to the thermonuclear fusion, which will radiate outwards from its body into the space around it.
A star’s large size will create large amounts of gravitational force, and this often means that planets or objects will orbit it, thus forming a solar system.
At the end of a star’s lifespan, however many billions of years that might be, its ability to continuously create a nuclear reaction will begin to stop, and it will become a stellar remnant.
Depending on how big the star is this could be a white dwarf or neutron star, which slowly produce less heat or light over time before disappearing completely, or, if the star is big enough, a black hole, which is an area of space with such strong gravitational pull that nothing, absolutely nothing – light, particles, molecules, dust, energy, metal, and so on – can escape its grasp.
Sometimes, a supernova is triggered in a star, whereby, in effect, the star will blow up and send shockwaves through the galaxy. In this event, materials and elements are blown away, which can form new nebulas or new planets, thus beginning the cycle anew.
So, is the sun a planet or a star?
The sun is a mid-sized star. The reasons for this are pretty simple. For starters, it’s enormous and even the largest planet in our solar system, Jupiter, could fit inside it 984 times. The sun is also in a continuous state of thermonuclear fusion and has been since it formed over 4 billion years ago after the collapse of a large molecular cloud.
This state of thermonuclear fusion produces light and energy for our entire solar system and is particularly important to life on earth, which relies upon its output.
The sun is orbited by all the planets in the solar system, having the largest and most dominant gravitational force of any celestial body in the region, and it makes up 99% of the matter in our solar system as well. In its current form, the sun is approximately halfway through its life span at about 4.5 billion years old.
In another 5 billion years, the sun will use up all of its hydrogen and will begin the process of becoming a planetary nebula and then a white dwarf over 100 million years before ceasing to be completely.
Then, if a nebula forms and sparks a thermonuclear reaction, a new star might be born in the sun’s place, starting the cycle anew.
Our sun is a star and the earth is a planet. The differences between the two are difficult to see for those of us stuck on earth and only viewing celestial bodies as shining tiny balls in the night sky, yet when you look into the space beyond our world even a little bit, the differences become obvious.
In fact, looking into the sky during the day and at night will tell the differences easily. If you can search the night sky, then maybe you’ll see a planet, but I guarantee that if you search for the sun in the daytime, you will almost always find it.
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