Ten Things You Don't Know About the Sun

By Phil Plait | March 3, 2009 6:00 am

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Comments (63)

  1. Nice green flash. I knew all of these (more or less), but I want to add #11, which I think is cool: We’re all made of sun. Maybe not our sun, but sun nonetheless.

  2. Tomas

    Nice one Phil, you simply never disappoint. I knew 9 out of those 10. BTW, another one like that about Sirius, is to ask what is the closest star. That usually ends up even worse because, unlike α CMa, most people heard of the Centauri system stars…

  3. Brian Schlosser, Lurker

    Excellent, as usual, Dr. Plait!

    Re: Neutrinos, The missing neutrino puzzle was the basis for my favorite Arthur C Clarke novel, “The Songs Of Distant Earth”… I’m glad it was solved in a way that DIDN’T involve the sun going nova…

    This article really makes me want to invest in a solar telescope. You are right: we do take the sun for granted. Backyard astronomers like me spend hours squinting at stars dozens of LYs away, while a perfectly fascinating star is only 8 minutes away (as the photon flies)! I shall endeavor to pay our sun more attention in the future…

  4. Amazing Phil! Simply Amazing! Keep it coming…

  5. Charles Boyer

    This is the sort of entry that makes this site invaluable.

    Not that the other ones are not entertaining and informative, but generally, they’re more topical and not entries one captures to teach youngsters about their local neighborhood in the Universe.

    Very well done, Phil and thank you.

  6. All that, just 150 million kilometers (93 million miles) away.

    Sleep tight.

    I will, with eight thousand miles of (mostly molten) rock blocking me from it while I’m asleep.

  7. Charles Boyer

    Oh, and #5 is partially explained by our friend Rayleigh. He was a bit scattered, but he loved the blues and Coldplay’s “Yellow.”

  8. Marko Germani

    But… the Sun being white… Isn’t it the other way around? It’s some millions years we are used to that light, our eyes got optimized for it. There was, according to Darwin, a kind of ape that saw the Sun green, but got extincted with the first traffic lights 😛


    Dr. Phil Plait: “… there’s a lot about the Sun that’s still not understand.”

    Posted at 6:00 a.m.! Are you up early or up late, Phil?

    I think that you’re up late, that should be “understood”, not “understand”. :-)

  10. Ryan Brown

    You forgot to mention the current utter lack of sunspots. That and the fact that the predictions for the next solar maximum keep getting pushed back a few months at a time. These are important facts for the coming decades and ones that prove we don’t know as much as we think we do about that giant ball of fire.

  11. Angry

    Cough cough. I must laugh.

    10 things i don’t know about the sun? More like 1 thing; I only didn’t know number 8. And I’m only 15 years old…

  12. Sir Eccles

    #6 is just a lovely example of how science works properly. Prediction, experiment, problem with results, new prediction, new experiment etc etc

    None of this “I give up, we puny humans are too stupid to do this, let’s just say god did it and go home” rubbish.

  13. I love the “Ten Things…” series. Keep them up, Phil.

  14. BigBadSis

    Sleep tight??

    And to think I lost sleep this week thinking about how much I’ve lost on the stock market! Great post, Phil.

  15. Greg

    Hey Phil,

    I want to see this on your Facebook page as one of those “X Random Things You Should Know” notes.

  16. Dave

    You’ve outdone yourself with this post Phil :)

    Fantastic read, thank you.

  17. I knew that massive stars are relatively rare, yet I had bought into the “Sun is below average” idea. It’s always interesting to discover a little bit of cognitive dissonance going on.

  18. OK, so the Sun is pretty bright. Ever wonder why?

    Genetics? Raised in a nurturing household?

  19. gopher65

    That looks like it was quite a bit of work to write.

  20. So you won’t go permanently and totally blind from looking at the Sun… unless you do it looking through binoculars or a telescope.

    When I was a kid, I used to look at the Sun quite often through my telescope.

    Of course, I had a solar filter on the lens, through which you could only see the Sun and the filament of a light bulb.

  21. Nemo

    I’d say that the Sun defines “white” for us, since our eyes evolved to match its spectrum. And the mid-day Sun has always looked white to me, when I’ve dared to glance at it. I guess I tend to think of the “yellow” Sun as being like the iconographic heart shape that’s shaped nothing like a heart.

    Re: the Sun’s averageness, one way to look at it might be: given a random hydrogen atom, how likely would it be that it would be found in a star of about the Sun’s mass? (Or: how many would be found in stars of lesser mass, vs. how many in stars of greater mass?) I don’t know the answer, but I wonder if framing it that way would make the Sun seem more average.

  22. If you were to pluck the Sun from the solar system and plop it down in some random location in our Galaxy, there’s a better than 99.99999% chance it would be invisible to the naked eye.

    Not that it would matter much, since all life on the Earth would die pretty quickly without the Sun nearby. (Unless you took the Earth with you when you plopped the Sun down elsewhere, in which case it would still be quite visible during the day.) :-)

  23. Jeff

    Hang on, let’s be clear about the fusion business – one often hears E=mc^2 being invoked to explain how fusion produces so much energy, but really it has no more relevance to fusion than it does to any normal form of burning. The tremendous amount of energy released in nuclear fusion stems from the strength of the strong nuclear force, not because matter is being converted into energy (a la matter/anti-matter annihilation). It can be quite misleading as well; I recently read an article massively over-estimating the potential energy yield from fusion, by assuming that all of the mass would be converted to energy.

  24. When I use that old, “What’s the brightest star?” line to new friends and acquaintances (old friends and acquaintances having long since learned to avoid me), I will invariably get at least one wiseacre who responds, Eta Carinae. Now how this person knows that bit of astronomical trivia (probably saw it on the bottom of a Snapple bottle cap) is beyond me, but the fact they can pull it from memory pretty much ruins the whole set-up.

    Now I have to be careful to say, “Which star is apparently the brightest as seen from Earth?” which just doesn’t have that zing to it.

  25. rob


    Your Kansas lyrics made me think of Joni Mitchell at woodstock. She sang that we are all made of atoms from long dead stars:

    “We are stardust
    Billion year old carbon
    We are golden
    Caught in the devil’s bargain
    And we’ve got to get ourselves
    back to the garden”

  26. Isn’t the Sun’s yellowness explained because its white light has the short-wavelength (blue) components Rayleigh scattered by particles in the atmosphere, leaving more yellowy-white?

  27. IVAN3MAN

    Dr. Phil Plait:

    Thing is, that pesky c in the equation is the speed of light, which all on its own is fast enough, but here we’re squaring it too, making it a seriously ridiculous number (about 1011 km2/sec2 if you’re keeping track at home).

    Err… Phil, how did you arrive at that figure? The speed of light in a vacuum is exactly 299,792,458 metres per second (due to the definition of the metre). So, c2 is ~8.99×1016.

    P.S. Yep, I’m keeping track! :-)

  28. alfaniner

    “Sirius is the brightest star in the night sky.”
    If the Sun was a lot farther away, it would be night… :)

  29. Such great descriptions. Succinct without being dry. This really is your forte, Phil.

    Yet, I’m still going to tell my kids they’ll go blind looking at the sun. I correct this when I have confidence they won’t aim for winning a Darwin award.

  30. Sarcastro

    So what color would Raleigh Scattering make, say, Betelgeuse look like on a terrestrial planet? Still red?

    Just interested because I used Betelgeuse and Rigel the other night to show my nephew that stars do indeed have colors.

  31. John Foudy

    “I’d say that the Sun defines “white” for us, since our eyes evolved to match its spectrum.” That’s what I was thinking, but Nemo beat me to it.

    Actually I’ve always been baffled by the statement that the sun is yellow- it’s never appeared yellow to me- typically it appears red to me, then picks up a reddish hue near the horizon- but it has never appeared yellow to me.

  32. Jeff, both explanations are perfectly valid. Also, since the fusing nuclei are quark-gluon plasmas it is not at all obvious that the mass difference cannot be attributed at least in part to net matter-antimatter (in this case gluon-antigluon) annihilation.

    Great essay, Phil. There were quite a few bits that I didn’t know.

  33. gray lensman

    Great article! I guess that the sun is a natural object to worship if you just have to worship something. It makes everything we are and do possible. It is always present and we can feel and see the effects daily. It is effectively omnipotent and will last forever as far as we will know anything about it. Most importantly, it marks our place in the universe. As someone said, if you are observing the solar system from Outside, our little neighborhood is just the sun, Jupiter, and some junk. So much for the geocentric view of the world.

  34. Jeff
  35. IVAN3MAN

    “Yes, we KNOW about evolution. Deal with it”!

    Heh! Good one, Phil! 😀

    RE: Your tidy bedroom in the background of that video in part 3 of your post.

    My bedroom looks like Nagasaki after “The Bomb” was dropped!

  36. QUASAR

    6.3 billion years?

    Some say 4.5 to 5 billion.

  37. QUASAR


    I know all those things about it!

  38. Brian Schlosser, “as the photon flies” that would be zero minutes! 😉

  39. Quiet Desperation

    Quick! What’s the brightest star in the sky?

    ME! :-)

    sing with me!

    That is why all the girls in town
    Follow me all around.
    Just like you, they long to be
    Close to ME.
    — The Carpenters (paraphrased)

  40. Brilliant! Once again, I’ve learned several new things and had fun doing so! Dr. Phil, why don’t you have your own TV series? I’m thinking a continuation of where Sagan left off: The New Cosmos with Dr. Phil Plait. Or something more original: Dr. Phil Plait Just Blew My Frakking Mind, Man would be great with the 2 AM stoner crowd.

  41. ozprof

    Hi BA,

    Interesting article. However I am surprised that you admit that you did not know some of them before you wrote your book. All of those you mentioned I cover in my Astro 101 introductory astronomy class!



  42. IVAN3MAN

    Dr. Phil Plait:

    The idea that stars use nuclear fusion to generate energy is credited to Hans Bethe, who thought of it in the 1930s.

    Actually, it was Sir Arthur Eddington who first proposed the idea that the pressures and temperatures at the core of the Sun could produce a nuclear fusion reaction that merged hydrogen (protons) into helium nuclei, resulting in a production of energy from the net change in mass. The preponderance of hydrogen in the Sun was confirmed in 1925 by Cecilia Payne. The theoretical concept of fusion was developed in the 1930s by the astrophysicists Subrahmanyan Chandrasekhar and Hans Bethe. Hans Bethe calculated the details of the two main energy-producing nuclear reactions that power the Sun.

  43. Pat Durrell

    That being said, this list (which is excellent!) would be a *great* addition to any Astro 101 course.

  44. José

    I still don’t get the color thing. What happens when you make a pinhole camera and project the sun on a white background? I see a yellow circle. Is that just me? If I shine a white light flashlight on the same white background, I just see a brighter white.

  45. Another “Things that will make you go blind” myth busted!

  46. picojoules

    thank you.

    just marvelous.

  47. cjsavvy

    God said, “Let there be light.” And the Sun was.

  48. Jack Mitcham


    According to my astronomy 101 book, some mass is actually converted to energy during hydrogen fusion. The short version is hydrogen fusion take 4 hydrogen atoms and turns it into a helium atom. That’s 4 protons into 2 protons and 2 neutrons. A neutron has less mass than a proton. Where does that extra mass go? Gamma rays, positrons, and neutrinos. The gamma rays get bounced around in the sun, being absorbed and re-emitted, until they reach us at various wavelengths.

    The long version appears much more complicated than that, but in short, yes, matter does get converted to energy.

  49. sam

    The next/previous thing is annoying and a cheap way to increase page views.

  50. For some reason, I expected to see Phil pop the four (He) mini-marshmallows into his mouth and ‘burp’, explaining: “gas”.


    [off topic]
    Two things you may not have known about Brian Cox:
    He hosted a show recently run on the Science Channel: What Time Is It? about the nature of Time (Space/Time) (also, I don’t see any upcoming repeats of it in the immediate future)
    He will appear on the second episode of the upcoming NBC series KINGS – see link to SciFi Wire, with the mention at the end of the article

    [/back on topic]


  51. Hello, Mr. Plait, I was viewing your video on page 4 about the density of the center of the sun, and while watching out of the corner of my eye at exactly 1:40 I noticed a kind of ‘ghostly’ object fly behind you. It appears to whip through the air in a downward, slanted motion.

    Of course, this maybe nothing but just a blip on the video or whatever, but recently I have been listening to Coast to Coast AM and Mr. Noory had a guest who spoke about ‘unseen’ objects recorded on video…mostly of what they call ‘shadow people’.

    By the way, love the blog. Peace.

  52. I just looked, and I think it’s a dust mote right in front of the camera, so it’s out of focus. :)

  53. I learned so many different things about the Sun!!! I hope they put more things up!!

  54. nayrevets

    Great article! I now have a sense of solar superiority over 80% of other systems. Also cool to note that the sun is “only” 1.4 million km across, making it barely 100 times the diameter of the earth!

  55. Jared

    There’s always Charlie Stross’s solution to long-term survival. First, siphon off most of the sun’s mass for storage and dunk a black hole into what’s left. Use the accretion disk to light and heat Earth (which will have to be moved much closer in). Then keep a whole bunch of brown dwarfs on hand to feed it periodically for the next few trillion years.

  56. Very informative blog on astronomy, and I think this would be helpful for kids studying about the subject in school.

  57. Anush

    I didn’t read all the replies, so forgive me if my comment is a repeat.
    My physics teacher in school put it very simply. ‘When light enters the atmosphere it breaks due to all the interference, which creates the rainbow. That’s why sunset color progression stricktly follows the rainbow: starts with red, then orange, green, blue, violet. If one would “unfracture” the light, we would get pure white color. Therefore, Sun is white.’

  58. Rasmus

    No, the sun certainly isn’t average. But it’s something else, it’s roughly “mid-mass”. The heaviest stars are roughly 100-200 times heavier than the sun, and the lightest are, equally roughly, 100 times lighter. I suspect this is the origin of that “average” myth.

  59. AndresMinas

    Re: Neutrinos.

    I can see that this article was written in 2009. Indeed, neutrinos are naughty particles doing some “free ride” on photons, thereby acquiring apparent mass in the process.

    The SM is not wrong, yet.

  60. Don’t worry the Great Sun Goddess is the same dame flame blang she always been.


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