This giant fireball at the center of our solar system needs no introduction. Every person is aware of what the Sun is and where it is located. The Sun is the life giver when its rays reach a particular planet in optimum amounts, and our Earth is one such lucky planet. Apart from the benefits the Sun provides, it is also of great religious importance to many people and has been so throughout the history of Humans on Earth.
The Sun is a star that is the closest to the Earth and the center of the solar system. Looking at the sky, don’t you ever wonder, ‘how big is the Sun?’. Pretty sure you must have. When you wake up in the morning and see an orange ball rising and similarly see it set, this question is bound to rise in your head.
We see it as a small orange ball in the sky, but the Sun is anything but a small ball. The Sun is capable of fitting all the planets of the solar system within it and even more!
Here we shall attempt to answer the question of ‘how big is the Sun?’ and put an end to your queries.
1. Measuring the Sun: A Brief History
The credit for the first beginnings to attempt to measure the diameter of the Sun can be given to Greek astronomers. They tackled the measurement from an astronomic point of view.
Greek scientists used innovative geometric techniques to determine the Sun’s diameter for the first time. Around 310–230 BC, Aristarchus of Samos established the solar diameter as the 720th part of the zodiacal circle, or 1800 seconds of arc.
In the ‘Sand-reckoner’ a few years later, Archimedes (287–212 BC) noted that the apparent diameter of the Sun looked to lie between the 164th and 200th component of the right angle, allowing for an estimation of the solar diameter between 1620 and 1976 or 27’00 and 32’56.
However, their estimates were erroneous and weren’t questioned for a very long time over the years. This problem is not just historical. Their initiation led to many more discoveries later, such as Ibn al Shatir of the Marāgha school making significant findings in his quest to estimate the solar diameter, including its annual change, which led to the eccentricity of the Earth’s orbit.
Around 1660, Gabriel Mouton did pioneering work in measuring the Sun’s diameter with astronomic precision, followed by Picard and La Hire. However, the scientific community is still working on an agreed-upon definition and value of the solar diameter despite significant efforts since the 17th century.
It can be considered the turning point in the astrometric estimation of the solar diameter and the development of new techniques, on the ground and in space.
2. How Big is the Sun?
The radius of the Sun is 696.34 km, and the Sun has a diameter of 1.39 million km. These figures can help you figure out the question, “How big is the Sun.” The Sun can fit more than one million piles of Earth in it, and about 1000 Jupiter can fit inside the Sun.
All the planets’ total mass in our solar system is only 0.2% of the Sun’s mass! It is safe to say all the planets are dwarf planets in front of this red giant. But here’s the catch: some stars in our Universe are even greater than our Sun. They are so huge that they make the Sun look like a spec of dust in front of them. We shall come across them further in the article.
3. What is the Sun Made Of?
The Sun is a big ball of gases, a yellow dwarf G-Type Main Sequence star that comprises about 70.6% of hydrogen and 27.4% of Helium when seen in terms of its mass and not atoms. It undergoes nuclear fusion in its core to transform hydrogen into Helium. This process will continue for billions of years to come, though it will gradually change.
When a star is called the main sequence star, it means that the star produces light and heat throughout this extended and stable era of its life by oxidizing the hydrogen in its core and changing it to Helium. Most of the stars in the sky will fall into the category of the main sequence star.
The photosphere is considered the surface of the Sun and is also what we see through our eyes from Earth. The surface of the Sun is not solid like that of the Earth, and you can’t firmly stand on it as we do on Earth. Don’t worry about that because you can never reach that close to the Sun because of the immense heat it throws.
We should never look at the Sun directly through the naked eye since its excellent brightness is harmful and can even lead to a lot of damage, such as short-term damage- that burns the Cornea- known as Solar Keratitis. Always look at the Sun with proper protection of the eyes.
4. Color of the Sun
We consider our Sun to be yellow or orange and have believed so since childhood, and our drawings from then are an example of this belief. But in actuality, the color of the sun is white! Hard to believe, right? Join the club of disbelief.
The appearance of the yellow color of the Sun is owed to Earth’s atmosphere. Our planet’s atmosphere serves as a filter, blocking out the cool light spectrum and enhancing the warmer hues. The sky appears blue because of the refraction of the filtered blue light by air molecules. So if we look at the Sun from space, it will appear white.
5. Importance of the Size of the Sun
The enormous mass of the Sun is held together by the great gravitational pull and keeps the whole solar system in its place. This massive gravitational pull creates great pressure and temperature at its core.
The Sun is the powerhouse of the entire solar system and consists of 99.8% of the whole mass of the solar system. The size of the sun, if altered even a bit, can lead to many changes in the solar system. The effect can be as follows:
It will lead to a change in the gravitational pull of the sun, which in turn will affect the positioning of all the planets. Rethink about having a life on Earth since positioning the Earth from the Sun makes life on it possible.
Although it has been estimated that in about 5 million years, the Sun is expected to grow into a red giant and become a thousand times more its size, and everything in the solar system will become a part of its core. Later, when the red giant phase of our sun ends, it will get smaller until it is the size of the Earth and, after that, change into a white dwarf.
6. How is it Measured?
No, we don’t use an inch-tape or a ruler to measure the diameter of the Sun or these stars; you got that wrong, pal. These celestial objects in the sky have a technique to measure them since these are not solid balls of mass but huge balls of blazing gases.
Measuring the Sun is complex since stars have diffused edges and not rigid surfaces in which we can distinguish where the gas ends, and vacuum begins. Therefore, locating the point where the star ends is a little tricky. To know the answer to the question of ‘how big is the Sun?’, it is also necessary to understand how the Sun and other such stars are measured.
Astronomers rely on the sun’s photosphere to measure the size of the Sun and other such stars. Astrophysicists consider it as the surface of the Sun. It is where the Sun becomes transparent to light, and the photon (particles of light) leave the star.
7. Sun and the Planets of the Solar System
Here we shall compare all the planets of our solar system with the Sun and see which planet will fit inside the Sun how many times. This shall give us a little more clarity about the question of ‘how big is the Sun?’.
It is the closest planet to the Sun and the smallest but not the hottest one. Around 21 million Mercury-sized planets can fit inside the sun as it is 277 times larger than Mercury.
The second in line and the hottest planet, Venus is 115 times smaller than our Sun, and about 15 million Venus can fit inside the Sun.
Third in line, and the only planet capable of sustaining life due to its perfect distance from the Sun, is our home planet, Earth. The Sun is 109 times the Earth, and some 1.3 million Earths can fit inside the Sun with ease.
No, it’s not the chocolate we love but the fourth planet of the Solar system and our neighbor. The Sun is 207 times Mars and can fit 7 million Mars. Although God knows how many Mars chocolate bars could fit inside the Sun.
The largest planet in our solar system is also called the gas giant. It, truly, is a gas giant. Since the Sun is only 11 times the size of Jupiter and 1000 fit can fit inside the Sun.
The first of the ringed planets, Saturn is the second largest planet. Sun is 12 times Saturn and can accept around 1600 Saturns in it.
Uranus is the third largest planet in terms of diameter in our Solar system and seventh in position. The Sun is 27.7 times Uranus and 22, 000 Uranus can fit inside the Sun.
Neptune is the last planet in the Solar system. It is 27.4 times smaller than the Sun, and around 1800 Neptunes are capable of fitting inside the Sun.
8. Sun at a Universal Level
When we look at the Sun just as a part of our solar system, our Sun is a huge mass ball. But the moment we step out of it, we realize that our sun is nothing in size compared to the other giants floating in the Universe at the cosmic level.
It is one of the billions of other stars strewn around the cosmos and is an average-sized star on a somewhat remote arm of an average-sized barred spiral galaxy. Hard to digest, right? But it is a fact that there are stars way bigger than our sun is, and they make it look like a planet in front of them. These huge stars of the Milky way have diameters 100 times the Sun!
9. Sun in Comparison to the Other Stars
These bigger celestial objects are known as giant stars, supergiant stars, or hypergiant stars. Let us look at a few well-known stars that overpower our Sun in all aspects.
9.1. Mu Cephei
The star Mu Cephei is 1500 times the size of our Sun. If placed at the center of our solar system, it will cover up orbits beyond Jupiter. It falls in the category of the red supergiants stars and is 38,000 times brighter than the sun.
It is one of the largest stars that can be seen with the naked eye despite its distance and is also known as the Garnet star because it is deep red and is somewhat 1550 lightyears away from us.
This red giant is 700 to 900 times larger than our Sun and 14,000 times brighter. It is located in the Orion constellation and is one of the biggest and brightest stars discovered.
It is somewhat smaller in size than that of Mu Cephei. Since if it is placed at the center of the Solar system, it will take up space equivalent to the orbits of Mercury, Venus, Earth, and Mars altogether.
This red supergiant star abruptly and spectacularly diminished last year before entirely regaining its former brightness; the fading is evocative of that star. The dimming left researchers wondering about the possibility of a supernova explosion for Betelgeuse shortly. But of course, Betelgeuse has not erupted.
Antares A is yet another red supergiant and is almost 430 times larger than our Sun and is 600 years lightyears away. It is regarded as the point where we begin to see the largest stars of our galaxy and is the 16th brightest star in the night sky.
9.4. UY Scuti
UY Scuti is a red hypergiant and can be called the largest star found in the Universe. It has a radius 1700 times larger than the radius of the Sun. To get a clearer picture of how big is the Sun in front of this hypergiant, we should see how many Suns can fit inside UY Scuti. Around 5 billion Sun could fit inside UY Scuti if it were hollow!
UY Scuti initially went by the name of BD-12 5055 when it was first discovered in the year 1860 by German astronomers at the Bonn Observatory. Upon continued observations, it was realized that this huge star grew brighter and dimmer over 740 days and was later classified as a variable star.
This star is located at the center of the Milky Way galaxy and is a part of the Scutum constellation. It is at a distance of 9500 lightyears from the Earth. These Hypergiants stars are rare to be found and lose much of their mass to the fast-moving stellar winds.
A few other stars are ready to take this hypergiant’s place if its size is altered, and they also currently measure 1700 times the Sun’s radius. WOH G64, Westerlund 1-26, NML Cygni, KY Cygni, and VY Canis Majoris are a few known ones.
9.5. VY Canis Majoris
Since this star is so large, it is considered the red hypergiant and is about 1300 to 1420 times larger than our sun and 300,000 times brighter. This huge star makes the Betelgeuse looks like a dot in front of it; forget about our Sun.
This star is located in the direction of our constellation Canis Major, the Greater Dog. According to the astronomers, this giant has also lost some of its brightness and has faded, just like Betelgeuse, although they also figured out the reason.
Using the Hubble space telescope in the year 2021, the astronomers figure the reason is this hypergiant star is emitting huge gas clouds that create dust, and this dust is blocking its light increasingly over time. It is said that VY Canis Majoris is behaving a lot like the Betelgeuse.
The sad news is that these extra large stars have shorter life spans than stars that are average-sized, like our Sun. Our sun has lived for four and a half billion years and is still regarded as middle-aged, whereas VY Canis Majoris is considered in its “old age,” although it is only 10 million.
Speculating about the life of the VY Canis Majoris continues; some think it might enter the supernova stage and explode, while others say that it might skip this stage and directly become a black hole. All we can make this guess right now until the time comes.
9.6. Stephenson 2-18
Since 2020, the biggest known star is the Stephenson 2-18, and it has surpassed VY Canis Majoris, Betelgeuse, and UY Scuti. This star is truly a behemoth and has a radius of around 2150 times that of the Sun!
To understand how small the Sun is in front of this biggest known star, we shall see how many Suns can fit inside it. More than 10 billion Suns would be required to fill Stephenson 2-18. But this might change since Stephenson 2-18 is not yet finished growing up. It is a relatively very young star and is likely to get even bigger soon!
These are the only known stars yet; we might encounter even bigger stars that might be capable of breaking the record soon.
10. The Expanding Sun
Well, our Sun is indeed getting bigger and hotter as the days pass, but this is something people should not worry about. Right now, our fireball is in a quiet phase of its life. Since it is very normal and every star goes through this phase.
The Sun has supposedly grown 20% of its size since its formation. This happens because the hydrogen continuously burns up to form Helium at the core, leading the core to collapse with the heat and the outer layers of the Sun to expand, hence the growth of the size.
In the next 5 billion years, the Sun is expected to become the red giant star when it starts its Helium burning process. When this happens, the inner planets such as Mercury, Venus, and Earth will be completely engulfed by it.
11. Final Thoughts
The Sun is extraordinarily large to Earth yet extraordinarily small to some of its far-off partners in the Milky Way, as we have seen above. Therefore, the local behemoth is appropriate in describing ‘how big is the Sun?’.
The size of the Sun may have failed to make it unique in the Universe, as there are even larger ones to take that spot. But since it is the ideal size, shape, and distance from us to enable life on Earth, it is particular to us. It is of great importance to us Earthers and will stay so.
A star with habitable planets that can support life has yet to be discovered in many aspects.