{"id":54228,"date":"2024-01-30T08:30:00","date_gmt":"2024-01-30T08:30:00","guid":{"rendered":"http:\/\/7150ba2c-bf3a-44ea-8e1b-cbaa0f852d39"},"modified":"2024-01-30T08:32:33","modified_gmt":"2024-01-30T08:32:33","slug":"scientists-may-have-solved-the-suns-biggest-mystery-why-its-outside-is-hotter-than-its-inside","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/scientists-may-have-solved-the-suns-biggest-mystery-why-its-outside-is-hotter-than-its-inside\/","title":{"rendered":"Scientists may have solved the Sun’s biggest mystery: why its outside is hotter than its inside"},"content":{"rendered":"

Has one of the biggest mysteries about the Sun finally been solved? <\/p>

By Anita Chandran\n <\/p>

Published: Tuesday, 30 January 2024 at 08:30 AM<\/p>

\n\n

When solar scientists measure the external layers of the Sun, something strange happens, and it’s known as the Coronal Heating Problem.<\/p>

The corona, the outermost layer of the Sun<\/a>, is much hotter than the photosphere below it, and nobody seems to understand why.<\/p>

However, a study by Ryan Campbell, a research fellow at Queen\u2019s University, Belfast whose research focuses on magnetic fields<\/a> in the Sun\u2019s outer atmosphere, may have shed light on the mystery.<\/p>

We spoke to Campbell to find out what the study involved.<\/p>

Biggest questions about the Sun – answered!<\/a><\/em><\/strong><\/p>

Ryan Campbell is a research fellow at Queen\u2019s University, Belfast, whose research focuses on magnetic fields in the Sun\u2019s outer atmosphere<\/figcaption><\/figure>
What is the Sun\u2019s outer atmosphere?<\/strong><\/h2>
It\u2019s easiest to understand from the inside out. The photosphere is the Sun\u2019s visible surface.<\/p>
It corresponds to a point in the Sun\u2019s atmosphere where visible light or \u2018visible photons\u2019 from the Sun\u2019s core can escape.<\/p>
Photons are emitted from atoms in the Sun\u2019s core and then re-absorbed by other atoms.<\/p>
This happens over and over again and the light can\u2019t escape.<\/p>
After a long time, one of these trapped photons will escape from the Sun at the photosphere.<\/p>
As you get higher above the photosphere, first through the chromosphere and then to the corona, you expect things to get less hot and less dense.<\/p>
But something weird happens as you reach the corona. Instead of the temperature decreasing, it shoots way up. Nobody really understands why.<\/p>
This is a big unresolved question called the Coronal Heating Problem.\u00a0<\/p>
$\"Miniature$
Miniature solar flares in the Sun\u2019s corona. The corona is much hotter than the layers below it. This is known as the Coronal Heating Problem. Credit: Solar Orbiter\/EUI Team\/ESA & NASA<\/figcaption><\/figure>
What are the potential solutions for the Coronal Heating Problem?<\/strong><\/h2>
Solutions to the Coronal Heating Problem try to explain why the outer layer is millions of degrees hotter than the layers below it.<\/p>
One explanation relies on wave phenomena in the lower layers, which transport energy up.<\/p>
Another relies on \u2018nanoflares\u2019. Most people have heard of solar flares: intense eruptions of energy in the Sun.<\/p>
Nanoflares are smaller flares occurring all over the Sun\u2019s surface, which could be an explanation for coronal heating.\u00a0<\/p>
What did your investigation involve?<\/strong><\/h2>
The presence of magnetic fields in the Sun\u2019s plasma changes the light emitted from the Sun.<\/p>
You can\u2019t physically go and grab a sample of the Sun and take it back to the lab; you have to measure emitted sunlight and work backwards.<\/p>
We know what sunlight would look like if it was emitted with no magnetic field, but with a magnetic field present we can look at the changes in the light to understand what was going on with the magnetic fields within the plasma.<\/p>
$\"An$
An active region on the Sun, as seen by NASA’s Solar Dynamics Observatory between 5-17 July 2017. This image shows a sunspot in visible and extreme ultraviolet light, with particles seen spiralling along magnetic field lines. Credit: NASA\u2019s Goddard Space Flight Center\/SDO<\/figcaption><\/figure>
How do you look at the Sun\u2019s corona?\u00a0<\/strong><\/h2>
You have to use a coronagraph. This basically blocks out most of the Sun\u2019s light with a disc so that you can see the corona, which is much dimmer.<\/p>
Because you have to block out most of the Sun itself, you can\u2019t look at the photosphere and corona simultaneously.<\/p>
Researchers are now pushing to use space-based tools, like ESA\u2019s Solar Orbiter<\/a> probe, at the same time as ground-based telescopes to view both corona and photosphere at the same time.\u00a0<\/p>
What did your study reveal?<\/strong><\/h2>
If you follow the direction of a small loop structure in the magnetic field of the photosphere, you\u2019ll find it goes up, across and down.<\/p>
This is important because, when we talk about energy transport through the outer layers of the solar atmosphere, one of the main mechanisms is magnetic reconnection \u2013 where magnetic fields that point in opposing directions can cause explosions of energy.<\/p>
We found a structure that goes up, across, down, across, and then back up, like a snake.<\/p>
These serpentine structures have never been observed before.<\/p>
Because they crest more than once, they have more chances for magnetic reconnection, increasing the potential amount of energy transferred.<\/p>
We only found one, but if these structures are common, this could be an important mechanism for energy release in the solar atmosphere, helping shed light on the Coronal Heating Problem.<\/p>
$\"Data$
Data from missions like the Solar Orbiter and Parker Solar Probe are helping solve the Coronal Heating Problem. Credit: ESA\/ATG medialab; NASA\/Johns Hopkins APL<\/figcaption><\/figure>
What does the Sun\u2019s magnetic field tell astronomers?\u00a0<\/strong><\/h2>
The Sun is a laboratory for physics.<\/p>
If you understand what\u2019s happening in the Sun\u2019s plasma, you can apply that to so many applications, from fundamental physics to fluid dynamics to plasma physics.<\/p>
A simple extension is to the photospheres of other stars, which may be hotter or cooler, dense or less dense.\u00a0<\/p>
What\u2019s next in your study of the Coronal Heating Problem?<\/strong><\/h2>
For these observations, we looked at atoms that absorbed particular colours of light in the photosphere.<\/p>
These are called absorption lines. Different atoms absorb photons of different colours at different layers of the atmosphere.<\/p>
Observing these simultaneously will help us to infer what\u2019s happening in the Sun\u2019s plasma at different layers \u2013 the photosphere, chromosphere or corona \u2013 at the same time.<\/p>
***This interview appeared in the February 2024 issue of BBC Sky at Night Magazine<\/em><\/strong><\/p> <\/body><\/html>\n***
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Ryan Campbell is a research fellow at Queen\u2019s University, Belfast, whose research focuses on magnetic fields in the Sun\u2019s outer atmosphere<\/figcaption><\/figure>
What is the Sun\u2019s outer atmosphere?<\/strong><\/h2>
It\u2019s easiest to understand from the inside out. The photosphere is the Sun\u2019s visible surface.<\/p>
It corresponds to a point in the Sun\u2019s atmosphere where visible light or \u2018visible photons\u2019 from the Sun\u2019s core can escape.<\/p>
Photons are emitted from atoms in the Sun\u2019s core and then re-absorbed by other atoms.<\/p>
This happens over and over again and the light can\u2019t escape.<\/p>
After a long time, one of these trapped photons will escape from the Sun at the photosphere.<\/p>
As you get higher above the photosphere, first through the chromosphere and then to the corona, you expect things to get less hot and less dense.<\/p>
But something weird happens as you reach the corona. Instead of the temperature decreasing, it shoots way up. Nobody really understands why.<\/p>
This is a big unresolved question called the Coronal Heating Problem.\u00a0<\/p>
$\"Miniature$
Miniature solar flares in the Sun\u2019s corona. The corona is much hotter than the layers below it. This is known as the Coronal Heating Problem. Credit: Solar Orbiter\/EUI Team\/ESA & NASA<\/figcaption><\/figure>
What are the potential solutions for the Coronal Heating Problem?<\/strong><\/h2>
Solutions to the Coronal Heating Problem try to explain why the outer layer is millions of degrees hotter than the layers below it.<\/p>
One explanation relies on wave phenomena in the lower layers, which transport energy up.<\/p>
Another relies on \u2018nanoflares\u2019. Most people have heard of solar flares: intense eruptions of energy in the Sun.<\/p>
Nanoflares are smaller flares occurring all over the Sun\u2019s surface, which could be an explanation for coronal heating.\u00a0<\/p>
What did your investigation involve?<\/strong><\/h2>
The presence of magnetic fields in the Sun\u2019s plasma changes the light emitted from the Sun.<\/p>
You can\u2019t physically go and grab a sample of the Sun and take it back to the lab; you have to measure emitted sunlight and work backwards.<\/p>
We know what sunlight would look like if it was emitted with no magnetic field, but with a magnetic field present we can look at the changes in the light to understand what was going on with the magnetic fields within the plasma.<\/p>
$\"An$
An active region on the Sun, as seen by NASA’s Solar Dynamics Observatory between 5-17 July 2017. This image shows a sunspot in visible and extreme ultraviolet light, with particles seen spiralling along magnetic field lines. Credit: NASA\u2019s Goddard Space Flight Center\/SDO<\/figcaption><\/figure>
How do you look at the Sun\u2019s corona?\u00a0<\/strong><\/h2>
You have to use a coronagraph. This basically blocks out most of the Sun\u2019s light with a disc so that you can see the corona, which is much dimmer.<\/p>
Because you have to block out most of the Sun itself, you can\u2019t look at the photosphere and corona simultaneously.<\/p>
Researchers are now pushing to use space-based tools, like ESA\u2019s Solar Orbiter<\/a> probe, at the same time as ground-based telescopes to view both corona and photosphere at the same time.\u00a0<\/p>
What did your study reveal?<\/strong><\/h2>
If you follow the direction of a small loop structure in the magnetic field of the photosphere, you\u2019ll find it goes up, across and down.<\/p>
This is important because, when we talk about energy transport through the outer layers of the solar atmosphere, one of the main mechanisms is magnetic reconnection \u2013 where magnetic fields that point in opposing directions can cause explosions of energy.<\/p>
We found a structure that goes up, across, down, across, and then back up, like a snake.<\/p>
These serpentine structures have never been observed before.<\/p>
Because they crest more than once, they have more chances for magnetic reconnection, increasing the potential amount of energy transferred.<\/p>
We only found one, but if these structures are common, this could be an important mechanism for energy release in the solar atmosphere, helping shed light on the Coronal Heating Problem.<\/p>
$\"Data$
Data from missions like the Solar Orbiter and Parker Solar Probe are helping solve the Coronal Heating Problem. Credit: ESA\/ATG medialab; NASA\/Johns Hopkins APL<\/figcaption><\/figure>
What does the Sun\u2019s magnetic field tell astronomers?\u00a0<\/strong><\/h2>
The Sun is a laboratory for physics.<\/p>
If you understand what\u2019s happening in the Sun\u2019s plasma, you can apply that to so many applications, from fundamental physics to fluid dynamics to plasma physics.<\/p>
A simple extension is to the photospheres of other stars, which may be hotter or cooler, dense or less dense.\u00a0<\/p>
What\u2019s next in your study of the Coronal Heating Problem?<\/strong><\/h2>
For these observations, we looked at atoms that absorbed particular colours of light in the photosphere.<\/p>
These are called absorption lines. Different atoms absorb photons of different colours at different layers of the atmosphere.<\/p>
Observing these simultaneously will help us to infer what\u2019s happening in the Sun\u2019s plasma at different layers \u2013 the photosphere, chromosphere or corona \u2013 at the same time.<\/p>
***This interview appeared in the February 2024 issue of BBC Sky at Night Magazine<\/em><\/strong><\/p> <\/body><\/html>\n***
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