Our Star – Size comparison
Let’s talk about our star, the Sun. Our star may seem like a giant but it is actually really tiny in comparison to the other stars in the universe.
So what is the size of the Sun? 696,340 km (Radius)
In comparison – The earth is 6,371 km
So how can you say that the sun is tiny? Well… There’s a star called UY Scuti which is 1700 times larger than our star. That number for reference looks like this.. 1,183,778,000 km in radius.
That is an unimaginable size. We won’t ever see something so large up close. But of course, there are bigger structures in the universe, like a Galaxy. If you’re wondering – our Galaxy, The Milky Way, is 52,850 light-years in radius. That translates to 5 × 10^17 km (what?).
Okay, I figured it out. That number looks like this 500 000 000 000 000 000. That is 500 Quadrillion.
If you want even more perspective.. In that space, you can fit 400 billion stars & 100 billion planets. Including the empty space in-between them.
A Protostar is like the infant of the stars. It’s not quite doing what a adult star is supposed to do yet. At this stage of its life, it is gathering up all the gas that surrounds it. The Protostar remains in this stage for about 100,000-500,000> years depending on its size.
A bigger star takes much longer.
The development stage is called Protostellar and during this stage, it gathers mass from its parent molecular cloud. The size of this type of star varies but on average it’s about 100,000,000 km in diameter and has a surface temperature of 2000-3000 K. The next stage consists of contracting the matter which leads us into the next stage. T Tauri Star.
How it Develops:
Gathering mass from parent molecular cloud
10^8 km (100,000,000) Diameter
2000 to 3000 K
T Tauri Star
In this stage in stars development, it classes as a variable star. During this time it’s still contracting to later start the fusion process, also called the pre-main sequence star. They are less than 10 million years old and have a central temperature of less than 2,500,000 K which is too low for hydrogen fusion to take place.
In its early stage, This star has a size comparable to a star in its protostellar stage.
Variable Star (not a specific star)
T Tauri stage
How it Develops:
Assumed to be similar to protostellar stage 10^8 km (100,000,000) Diameter (Not confirmed)
Main Sequence Star
Most stars that we know of are in this stage of their life, Our star, the Sun, is in this stage. At this stage, it is using nuclear fusion of hydrogen into helium to generate thermal energy. This is what we feel when the sun rises, heat.
Our sun has a core temperature of about 15 million degrees Celsius.
Our star has about 5.5 Billion years left before it runs out of hydrogen and starts burning helium, at that point, it will expand and turn into a Red Giant star, we will talk about that stage later.
How it Develops:
Burning hydrogen (Nuclear fusion into helium)
5,505 °C / 15 million °C
Red Giant Phase
At this point in its life, talking mainly about our Sun, it will become so large that the Sun will expand and engulf Earth. Before that, in about 1 Billion years, our oceans will boil away leaving our planet looking like Mars fresh out of the oven.
All of this happens because the star runs out of hydrogen to burn, so the nuclear fusion moves outwards into the atmosphere which is why it expands.
Red Giant phase
How it Develops:
Burning helium & nuclear fusion of hydrogen in the atmosphere, it expands and turns red. When hot enough it is fusing helium to carbon.
278,536,000 km (400 times larger than the original size of the star in the main sequence)
4,700 °C / 10^8 Kelvin
White Dwarf star
At the last stage of the Red Giant stage, the star will eject its outer layer forming a planetary nebula. Right after this phase it ultimately becomes a White Dwarf. Generating enough light to look like the full moon on a clear night.
Quite sad really.
Without nuclear fusion, the light comes from the last residual heat stored within the star. The mass of the sun, very dense, but has a volume comparable to earth.
White Dwarf phase
How it Develops:
Cooling and Crystallization
roughly the size of Earth
Black Dwarf phase
There are currently no black dwarfs in the universe that we know of, it is entirely theoretical. That is because it is believed that it takes longer for a star to get to this point in its life than the age of the universe. (Age of the universe: 13.8 billion years old)
So a quick rundown, this is what it is believed will happen to a white dwarf at the end of its phase. When the core is so cold that it stops emitting any heat or light. It is the corpses of stars.
This is what it is believed, according to current evidence and calculation, what will happen in billions upon billions of years in the universe. Effectively making the universe a cosmic graveyard filled with black dwarfs and black holes. No light, just matter.
Although, by chance, some black dwarfs may collide making accidental new stars.
Eventually, black holes will evaporate and explode which will be the only possible light in the universe.
Here is a very interesting and intense video that explains current theories about the future of the universe. Watch it, it’s amazing.
That is the life of Stars.. but there are more kinds of stars than what I wrote above!
A supergiant star is a star that is several hundred times larger than the Sun. It emits light a million times brighter than the sun and these stars only have a life span of a few million years. It emits heat that is 3,400 K to over 20,000 K.
What’s cool about these stars is that they end up exploding(supernovae) and turns into a Neutron Star or a black hole depending on the size.
A neutron star is a phase after a supergiant star goes supernovae. They are the collapsed cores of supergiant stars. If the star is more giant then the core continues to collapse into a black hole.
Starting at 600,000 degrees Kelvin it will eventually cool down and become a black dwarf. Yes, a Neutron star does not generate any heat or light. The light you would see is what’s leftover from its life as a supergiant star.
Red Dwarfs are the most common stars in our galaxy. They are very cold, reaching only 3,500 degrees Celsius instead of 5,505 °C that our sun is. Their expected lifespan is a mind-numbing 10 trillion years!
A black hole is not what it seems to our eyes, in fact, we can’t actually see a black hole. Why? Because they are so unimaginably dense and gravity is so strong that not even light can escape it. Then how do we know that black holes exist?
It’s relatively simple. Take the centre of our galaxy, the milky way, and we can observe Stars and gas flying violently around a black region of space. We can use this to determine that there must be something there that is affecting these stars, so since we can’t actually see one the only fitting name seemed to be “Black Hole”.
Another way is to observe the gas that is going around the black hole. Which we have and actually have a picture of!
So what are we actually looking at here? Technically it’s not the black hole we see, but the hot gas that surrounds the black hole. The gas sort of outlines it, and that’s what we are looking at because that is the only thing we could ever see since no light can escape the black hole to be picked up by our telescopes.
If you were wondering, Hypothetically the sizes of a black hole can go from microscopic to supermassive (bigger than literally everything).
If you want to learn more about black holes you can visit Wikipedia, they have a great page for it! I couldn’t even begin to explain all the details. Click HERE to open the Wiki-Page.
I hope you learned something about the very thing keeping us alive, the stars.
Thank you for reading!
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