Hannah Schunker, Lecturer of Physics, University of Newcastle
David Pontin, Associate Professor of Physics, University of Newcastle
Why is the sun’s environment hotter than its floor? — Olivia, age 9, Canberra
Hi Olivia, that is a fantastic query! In reality, it is such a fantastic query many scientists around the globe try to reply it.
The fact of the matter is — we don’t know! But we do have some concepts about the place the vitality that heats the sun’s atmosphere may be coming from, and it has so much to do with the sun’s magnetic subject. Let me clarify what this implies.
The temperature of the sun
Heat is created within the very heart of the sun, at its core, the place the temperature is a blistering 27 million levels Celsius. And similar to strolling away from a campfire, the temperature will get cooler additional away from the core.
The temperature of the sun’s floor is about 6,000 levels C, which suggests it is a lot cooler than the core. Also, it continues to chill down for a brief distance above the floor.
But increased above the floor, within the environment, the temperature out of the blue shoots as much as greater than 1,000,000 levels! So there should be one thing that is heating the sun’s environment. But we won’t simply discover out what it’s.
The key’s the sun’s magnetic subject
The main concept amongst specialists is the sun’s magnetic field is definitely bringing vitality from contained in the sun up by its floor and into its environment.
Like Earth, the sun has a magnetic subject. We can think about a magnetic subject as invisible strains connecting the north and south poles of a star or planet.
We cannot see magnetic fields, however we all know they’re there as a result of we’ve got objects that react to them. For instance, a compass needle on Earth will at all times level to the North Pole as a result of it strains up with Earth’s magnetic subject.
While the sun additionally has a north and south pole, its magnetic subject behaves in a different way to Earth’s and appears so much messier. At the floor of the sun, the magnetic subject strains appear to be many loops rising up out of the floor into the environment — and these loops are altering on a regular basis.
If the loops contact one another they’ll trigger sudden explosions of huge quantities of vitality that warmth up the environment. We additionally know there are waves touring alongside the magnetic subject strains bringing vitality up. Could they be chargeable for heating the environment?
Is it a mixture of the waves and the explosions, or one thing else altogether? Being capable of measure the sun’s magnetic subject would actually assist us perceive what is going on on.
Measuring the magnetic subject
Magnetic fields could also be invisible, however we will nonetheless measure them as a result of they make small modifications to the sunshine that comes from the sun. The floor of the sun could be very vivid, so it is simple to see modifications within the gentle coming from the floor, and measure the magnetic subject there.
But the sun’s environment is so sizzling the sunshine there may be not seen anymore. Rather it makes X-rays, that are a sort of sunshine we won’t see! Even if we use particular X-ray telescopes, the X-rays from the sun’s environment are too dim for us to determine what the magnetic subject within the environment appears to be like like.
The excellent news is there’s a model new satellite, NASA’s Parker Solar Probe, which is now orbiting near the sun (however not too shut) and really flying by the magnetic subject to measure it. We ought to be receiving quite a lot of thrilling new data from it over the following 5 years.
These magnetic subject measurements will deliver us nearer to understanding what’s making the environment of the sun, and different stars, a lot hotter than their floor.
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