• Question: Why is the sun hotter on the outside than than the middle?

    Asked by King LillEm to Lisa, Mark, Rachel, Sammie, Stephen, Tim on 13 Mar 2018.
    • Photo: Sammie Buzzard

      Sammie Buzzard answered on 13 Mar 2018:

      This is still an active area of research- the latest theories suggest that eruptions occur in the boiling plasma near the Sun’s surface that carry a lot of energy out to the Sun’s atmosphere meaning this actually gets heated up more than the Sun itself, but this is still a very new idea!

    • Photo: Tim Duckenfield

      Tim Duckenfield answered on 14 Mar 2018:

      Great question – this is exactly the question I study! Not all of us scientists agree exactly how, but we DO know that is has something to do with the Sun’s magnetic field. Somehow, the fact that the Sun is spinning and has a flow from the middle outwards, means a really strong and really complicated magnetic field is made. How this is made is another big question – we call it the “dynamo”…

      Anyway, this magnetic field gets dragged out of the Sun’s surface with the light and gas the Sun pushes out into space. And suddenly, about 2000 kilometers above the surface, WHOOSH the temperature rockets up from twenty thousand degrees to OVER 2 MILLION degrees hot!! That can be hotter than the middle! And this colossal, rapid change of temperature happens in a tiny tiny space, only about 100 km. We see that the magnetic field takes over at this point, and instead of the gas dragging the magnetic field around, the magnetic field becomes the boss and drags the gas wherever it wants!

      I want to understand why. So I measure waves that happen, to see what the magnetic field and gas is doing at this point in the Sun’s atmosphere. The exact reason why is unknown. Some people think the magnetic field causes lots of mini explosions called “micro-flares” which releases lots of energy as heat. Other people think it is caused by magnetic waves, that crash like sea waves crash on a shore. I hope to find the answer! So I measure waves that we can see happen, to work out what the magnetic field and gas is doing at this point in the Sun’s atmosphere. If I find out I will tell you!

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