Science Made Simple: Anatomy of Our Sun

Anatomy of Our Sun

Anatomy of our Sun. Credit: ESA


This is where the Sun generates its energy. The temperature in the core is around 15 million degrees Celsius (27 million degrees Fahrenheit). This, combined with the huge pressure and density of the plasma force hydrogen nuclei to fuse together, creating helium and releasing vast quantities of energy in the process. Every second, the Sun converts four million tonnes of matter into energy in this way, which begins a slow journey towards the surface.

Radiative zone

This is the layer above the core. Although not as dense as the core, the plasma is still packed so tightly in the radiative zone that convection cannot take place. Instead, the energy created in the core diffuses slowly through the plasma. It takes photons around 170,000 years to pass through the radiative zone: The photons travel at the speed of light, but can travel only a few millimeters at a time before they are absorbed by an atom and then re-emitted in any direction. At the top of the zone, the temperature is around two million degrees Celsius (3.6 million degrees Fahrenheit). At the base, next to the Sun’s core, the temperature is around seven million degrees Celsius (12.6 million degrees Fahrenheit).

Anatomy of the Sun

Anatomy of the Sun infographic. Credit: ESA–S.Poletti

Convective zone

This lies between the deeper, radiative zone and the photosphere. The convective zone is 200,000 km (124,000 mi) deep. While the top layer is the same temperature as the photosphere (between 4,500 – 6,000 degrees Celsius or 8,100 – 10,800 degrees Fahrenheit), the base of the convective zone reaches two million degrees Celsius. Plasma at the base of the zone is heated rapidly. This makes it buoyant and so it rises rapidly, creating a turbulent convection pattern, rather like a boiling pan of water – only 200,000 km deep and surrounding the entire Sun.


This is the boundary between the convective zone and the radiative zone. Below the tachocline, the Sun rotates like a solid body. Above it, the Sun rotates at different speeds according to its latitude. The change of rotation speed across the tachocline is very fast and this results in shearing forces that are thought to be important in the creation of the magnetic fields that lead to sunspots.


This is the visible ‘surface’ of the Sun. Almost all radiation from the Sun is emitted from this thin layer of several 100 km thickness, which lies at the upper boundary of the convection zone. It is where the energy generated in the core can finally move freely through space. The temperature of the photosphere varies from place to place but lies between 4,500 and 6,000 degrees Celsius.


This is the layer above the photosphere, where the density of plasma drops dramatically. In general, the chromosphere is roughly 1000–2000 kilometers (600-1,200 miles) thick, with a temperature that rises from around 4,000 to about 25,000 degrees Celsius (7,200 to 45,000 degrees Fahrenheit). Spires of chromospheric gas, known as spicules, can reach up to a height of 10,000 km (62,00 mi).

Transition region

This is a thin, irregular layer that separates the relatively cool chromosphere from the much hotter corona. Across the transition zone, the temperature of the solar plasma soars to nearly a million degrees Celsius (1.8 million degrees Fahrenheit). While the convection zone and partly also the solar photosphere are dominated by flows that are capable of moving regions of strong magnetic flux around, the transition region and corona are dominated by the magnetic field which forces the plasma to move predominantly along field lines.


This is the Sun’s outer atmosphere and extends to millions of kilometers into outer space. It is most easily seen during a total solar eclipse. The plasma in the corona is extremely hot at more than one million degrees Celsius, yet is very rarefied. Its density is typically just one trillionth of the density of the photosphere. The solar wind originates in the corona.


These are large structures, often thousands of kilometers in extent. They are made of tangled magnetic field lines that keep dense concentrations of solar plasma suspended above the Sun’s surface and often take the form of loops that arch up from the chromosphere. They can persist for several weeks or even months.

Solar flare

This is a sudden release of energy. A flare is usually created when the magnetic field lines that make sunspots transform themselves rapidly into more stable configurations. This is a bit like a stretched elastic band breaking and releasing all of its stored energy as it snaps back into position. The energy released by solar flares strongly influences the behavior of the solar wind.


These are temporary features on the photosphere. They look like dark patches against the brighter region of the photosphere because they are about 1,000 degrees cooler and so do not emit so much light. They are caused by magnetic fields breaking through the photosphere of the Sun and cooling the gas there. Sunspots can be anything from a few tens of kilometers across to larger than 150,000 km (93,000 mi).


These are convective patterns that occur in the photosphere. Each granule is about 1,000 km (620 mi)wide and consists of hot plasma rising in its center. As it releases its energy into space, the plasma cools and this makes it flow to the sides of the granule and sink back down into the photosphere. Individual granules persist for about 20 minutes, after this new ones in slightly different places develop.

Coronal mass ejections

These are vast eruptions of billions of tonnes of plasma and magnetic fields from the Sun’s corona. They travel out from the Sun at speeds of hundreds to thousands of kilometers per second, and if sent into the pathway of the Earth, can create geomagnetic storms.

45 Comments on "Science Made Simple: Anatomy of Our Sun"

  1. Great article. Great breakdown of the sun’s layer. Couple of things: how about moving the paragraph on the Tachocline after the radiative zone and some confusion on the Spires of chromosphere, is it 100,000km deep or 10,000km?

    • Man you a programmed/brainwashed sheep to beleive this nonsense….I guess they been to the Sun and went inside to see. Lol Sheep

      • Your post indicates you are barely literate, yet you know more about the Sun than our best astronomers? Why do I find that hard to believe?

        • My grammar has nothing to do with you being a sheep..lmbo

          Space and all that comes with it is literally the most impossible fantasy land thing imaginable… Everything is based off of assumptions, theories, non-provable, unobservable, made-up, and invisible mathemagical nonsense that exists only on paper and in the minds of liars… Space is Fake. Wake up, people!

          • Frank Hill | May 30, 2021 at 6:49 pm |

            Wow you are an idiot. We have a very large number of observations that show physics correct in many (but not all) respects. If space is an unimaginable fantasy how are you, a minor idiot, even thinking of it?

      • Troll much buddy? Or are you off your meds? So if all of this fake then what are you doing on a Science site?

    • Frank Hill dont feed me full of your bs… it’s all lies and CGI…you blind programmed fools need to wake up

      • JY, you’re apparently a programmed moron. Where did you get your “knowledge“ of science? From the Bible, a book of fairy tales?

  2. Aleksandr7364 | May 30, 2021 at 12:17 pm | Reply

    The picture is not correct. The sun inside is black. This is indicated by black spots, which are hundreds of times hotter :

  3. You should have mentioned that the sun (like all stars) is filled with sound waves and that the analysis of their frequencies, along with our understanding of physics, is how we know what is inside the Sun. Idiots like JY and Aleksandr7364 are completely out to lunch, as usual.

    • You should not be a programmed sheep. Lmbo

    • The Sun is not a star you blind space monkey…Its a light. Just light the moon. You beleive in Magic. Lmbo A spinning marble hurdling through infinite nothing while spinning 1000mph …With something called magic gravity holding the water to the ball. You people have no common sense

      • You call your nonsense common sense you narcissistic baboon? Solipsism is a farce, otherwise we would not need entertainment. And how do you think it works? Turtles on turtles?

        • You are blind programmed indoctintated fake space mon-key…there is no outer space. There solid firmament above us and they dam well know it..

    • Aleksandr7364 | May 31, 2021 at 11:38 am | Reply

      Frank Hill | May 30, 2021 at 12:49 pm The inertia of the old science lasts a long time. Until a wild man with a tail realizes that the sun inside is black – the sun will have time to burn out and turn red, as in the picture))

  4. Jim Nevermann | May 31, 2021 at 12:06 am | Reply

    JY, you also know, don’t you, that the moon is made of cheese (Parmesan, I think), the earth is –and always has been– flat. I mean, gosh, *any* fool knows those things to be 100% true, right?

    Heyyyyy… by golly, JY, you really SHOULD go on the “lecture circuit”. You’re obviously highly educated, not to mention *devastatingly* articulate. Gosh, you’d be an instant hit at the world’s great universities and, doubtless, a billionaire in less than a year!

    Just think of it, JY: Your erudite thoughts would eventually be published as Cracker Jack prizes! I can hardly wait! *belch*

  5. The energy at the core of our Sun is not fusion. Fusion is a conservation of energy. That is why it is basically impossible to create without adding massive amounts of electricity. Quark plasma is what the world is looking for and is what is at the core of our Sun. This plasma, once created, uses the dark matter of space as a catalyst. This plasma is so hot that it is invisible and can make shapes. This is what black holes are made of. It isn’t gravity that keeps light from being emitted, the quark plasma is simply too hot. All the elements that the sun is made of are simply trying to survive on the surface.

  6. JY what exactly is spinning at 1000mph? And how domypu know it spinning at that speed?

    • Really Tom? You dont know that the liars claim the Earth is spinning 1000mph while moving 67,000 mph though infinite nothing? And the water sticks to this spinning marble because of magic gravity..lmbo It ridiculous and ashame that the dumbed down programmed masses fall for it.

  7. JY, your skepticism is extremely important. The different ‘factual’ claims made in this brief article, are backed up by using probes like, Parker Solar Probe, sent by our NASA. Please go to their website to learn further about our Sun.
    European Space Agency and many other countries, uses probes to study our sun. Thanks to you for reminding us not to take things, on face value, we must investigate our assumptions

    • Dude are freaken serious? Probes? You dummies believe anything. Lmbo Oh the Probes came back to Earth…oh my gosh and batteries last 40 years…And helicopters and rovers fix themselves. Million of of miles away…you are brainwashed…dang

      • Your lack of intellect and grasp of the English language including basic grammar shows you have no business being on any science website. Go back and stay on QAnon.

    • This is your problem. You are so programmed you think that it’s not possible for all fake space to be involved. They are all involved in the fakery..learn signs, symbols and numbers you will figure it out and read your Bible…of course psuedoscience is your god

  8. Does JY have a brain? Until we actually see it, I’d refer to the negative

  9. JY, the Bible, the book with the talking donkey and centennials who live for 900 years?

    • I would believe a donkey talking before I would believe in magic gravity…Water sticking to a ball spinning 1000 mph…lmbo. while moving 67,000 mph though infinite nothing…batteries that last 40 years plus. ROVERs and helicopters that fix themselves millions of miles away though the vacuum of Fake space…lmbo Probes that somehow make it back to earth through the Chaos in space. I mean give a dam break. So called pictures of Mars. All they have to do is change the color of the image to make it look Red. And you jokers have faith in pictures…lmbo And those pictures of Mars look eerily similar to certain deserts on Earth. Lmbo

  10. Why are people on these threads always so determined to disprove the delusional slurs made by all the trolls and conspiracy junkies? Just accept them for what they are – entertainment – and move on FFS..

  11. Kolle Bangura | June 5, 2021 at 9:44 pm | Reply

    All this reminds me that hell is just next door. From hell thou has come and to hell thou art return.

  12. I greatly enjoyed the descriptions depicted here. The comment section, in addition, provided some disturbing amusement. 😀

  13. Dennis Maier | June 6, 2021 at 1:18 pm | Reply

    No way to actually know any of this all theory.

  14. Never argue with a self-admitted buttless man. Historically, topological considerations assure that his is also brainless!

  15. JY, if you don’t believe in space and you don’t believe in gravity then what creates our day and night, what heats the earth during the day and what keeps the water on this “spinning marble “?

  16. Idiot comments…..

  17. Marin Tomuța | June 9, 2021 at 2:12 pm | Reply

    Amazing that the Sun has a solid core. Solid hydrogen plasma? Or is the core made of helium and heavier elements?

    Replicating fusion seems to require extreme pressure which will in effect produce extreme temperature. We can make the plasma just not the pressures. We’d only need to do this to a little bit of matter.
    Any idea as to the pressures in the core? Pv=nRT.

    And what exactly happens to say a comet if it crashes into the star?
    Can one star absorb another and grow in mass? Is this what happens in the galactic center?

    Think of all that wasted energy radiating into space. We could capture more by ‘peppering’ outerspace (outside of Earth) with photovoltaics, maybe concentrate it and beam the energy where needed.

  18. Marin Tomuța | June 12, 2021 at 6:29 pm | Reply

    What if a star is a giant 3D printer that prints/builds larger particles from smaller ones (quarks to elementary particles to elements).
    What if the galactic core star is also but builds even heavier elements. And what if every star and galactic core also does this same process?
    But does the earth/planets have any fusion in their cores? Or just fission of unstable stellar heavy elements and molecular bonding to prevent further decay?

    • Marin Tomuța | June 12, 2021 at 6:31 pm | Reply

      ‘Nothing’ is the space between matter, but matter comes in many shapes, sizes and temperatures.

  19. Marin Tomuța | July 7, 2021 at 9:57 am | Reply

    Is it possible for hydrogen to exist as a near solid at such a high preasure despite temperature? Temperature and pressure are directly proportional but I think temperature is dependent on pressure in a star since heat radiates out.
    But what would keep it together? Attractive charges? Maybe the sun is more ‘chill’ than we think. Maybe there is a natural flow from higher gradient to lower. Maybe there isn’t any struggling or forcing (as we imagine it).
    [I don’t know; I’m near midlife.🌞]

  20. Vikram Singh Bhadoriya | July 31, 2021 at 10:44 pm | Reply

    Great article to feed the curiosity about the much talked about features of the sun. But also throw some light upon the condensation of mass to an state of unit mass of infinite density from which the universe is said to had emerged as per the speculations of Big Bang theory and that of Naasdeey sookta of Rig Veda. Thank you so much.

  21. Bhausaheb Bhosle | March 16, 2022 at 5:15 am | Reply

    The word is syllable, grammar, word and speech (verse). It is the speech of topmost height of truth, the last and the most faultless. Vedas is the verse of universe (uni-verse) of topmost height of truth. Where ever people speak of Vedas, they mean Dharma-Shastra (science of Religion) added by Manu from his Manu-Smriti (memory). Vedas is pure science. Vedas is a book of knowledge. It is the book of wisdom. Manu-smriti is a passing phase. Because of the poor population, the Vedas is finally supported by the backward classes who lived without thoughts throughout their lives. In the beginning of creation, there was nothing. In the beginning only He breathe calmly without any attachment, Only He existed. To the backward classes untouchables finally created the heaven for the god to attain immortality (Moksha) in space and time. To manifest any time anywhere in space and time to help the god to design the genetic drive for the son of god through the law of the soul. All my life, I considered Him to be my enemy number one. How wrong I was. God is great. He is greater than the greatest. Vedas was considered Dharma-Shastra and its true meaning was not known. They considered Vedas as meaningless. Dharma-Shastra was considered as the main Vedas. Manu took himself to propose the law of countries, castes and people. Finally, Kshatriya will reveal the true meaning of the Vedas when the enquiring man will be humbled, defeated than the age of the truth will begin. This is written in all the Vedas and the Puranas, even before the genetic drive started on the Earth. Many Kshatriya kings tried their hands at finding the true meaning of Vedas but they failed, as the new philosophy originated. “To cast Marthanda far away, to come to life and die again”. Vedas was considered as meaningless. Dharma-Shastra was considered as the main Vedas.
    Bhausaheb Bhosle.

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