Could Friday's solar eclipse solve the sun's biggest mystery? Spectacle may help reveal why the corona is hotter than the surface

  • A team of scientists is travelling to Svalbard to observe the solar eclipse
  • They will use an array of instruments to look at the sun's corona
  • This is plasma around the sun that can only be seen during a total eclipse
  • They hope to work out why the corona is 300 times hotter than the surface
  • Friday's eclipse will peak in the UK at about 9.35am GMT

By JONATHAN O'CALLAGHAN FOR MAILONLINE

Published: | Updated:

Why is the sun’s corona - the aura of plasma that surrounds it - so much hotter than its surface?

That is one of greatest solar mysteries, but astronomers will be hoping to find an answer on Friday - by observing the total solar eclipse from the North Pole.

The plasma of the sun is only visible during a total eclipse, so the scientists will use this unique opportunity to try and solve the puzzling phenomena.

And in an amazing coincidence, the eclipse will occur over the North Pole on the same day the sun comes into view after six months of polar night - an event which happens only once every 500,000 years.

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Shown is an image of 1999's solar elcipse from France, with the corona visible around the edges

A team of scientists is travelling to Svalbard to observe the solar eclipse. They will use an array of instruments to look at the sun's corona . This is plasma around the sun that can only be seen during a total eclipse. Shown is an image of 1999's solar elcipse from France, with the corona visible around the edges

The team of scientists will be working at an old observatory on Svalbard, midway between continental Norway and the North Pole.

They are travelling to this region to ensure they see totality - 100 per cent of the sun being covered by the moon during the eclipse.

For observers in other regions, such as the UK, less than 90 per cent of the sun will be covered.

The team at Svalbard, led by Professor Shadia Habbal, Professor of Solar Physics at the University of Hawaii, will include scientists from Aberystwyth University in Wales.

They are Joe Hutton and Nathalia Alzate from the Solar System Physics Group at the Department of Physics at Aberystwyth University.

They will join scientists from the US, Czech Republic and Germany as part of the 'Solar Wind Sherpas'.

Up to 14 specially adapted cameras will be used to photograph the sun in different frequencies during the eclipse, capturing images of the plasma from the corona.

In so doing, they will hope to solve the sun’s greatest mystery. 

The temperature of the sun is known to be around 6,000°C (10,800°F), but for some reason the corona is around 1,000,000°C (1,800,000°F), and even reaches 2,000,000°C (3,600,000°F) in some areas.

This factor of 300 difference would be akin to the flame of a fire being 300 times colder than the air around it - but why this is occurring is unknown.

One potential reason could be magnetic forces on the sun, with superheated gas creating a strong magnetic field and funnelling energy into the corona, but this has not yet been confirmed.

The team of scientists worked at an old observatory on Svalbard, midway between continental Norway and the North Pole (shown with the red marker). They travelled to this region to ensure they saw totality - 100 per cent of the sun being covered by the moon during the eclipse

The team of scientists will be working at an old observatory on Svalbard, midway between continental Norway and the North Pole (shown with the red marker). They are travelling to this region to ensure they see totality - 100 per cent of the sun being covered by the moon during the eclipse

OBSERVING THE ECLIPSE: HOW TO STAY SAFE WHEN VIEWING THE SUN 

Astronomer Gemma Lavender from All About Space magazine

Do you need special equipment to look at the eclipse? 

'It’s all too easy to look at the sun when an eclipse is happening, but you should never look at the eclipse with naked eyes, binoculars or a telescope without filters - otherwise you run the risk of permanently damaging your eyesight.

'That’s not to say that you can’t watch the eclipse on Friday - but you should ensure that you have the right equipment that will provide you with the right amount of protection.

'Dedicated telescopes such as solar telescopes can allow you to observe the eclipse with absolutely no risk. However, unless you already own one, know somebody who does or are looking to get into solar astronomy, they can be a massive investment of several hundred pounds.

'There are cheaper ways to observe the eclipse, though.'

Are solar glasses fine to use?

'Many people buy solar glasses or viewers to watch the eclipse. These can be bought quite cheaply from telescope dealers.

'They work by employing a Mylar film that blocks out over 99 per cent of the sun’s light, allowing you to view the eclipse safely.

'Before using them though, you should make sure that they are not damaged in any way and you should ensure that you have bought them from a reputable dealer. If you’re in doubt, don’t use your viewers at all.'

How can you use a telescope to observe the eclipse?

'If you own a telescope, then there are several ways for you to observe the eclipse.

'If you don’t own them already, it is possible for you to buy a solar filter, which covers the aperture of your telescope to ensure that you can observe the sun safely.

'They are found to be made of glass or as with the solar glasses, Mylar film. It is possible to make a solar filter using Mylar sheets but caution is advised while making your own solar filter - any scratches or pinholes will lead to dangerous amount of sunlight entering your eyes.

'You should also avoid relying on eyepiece filters - they cannot handle the sun’s light. 

'Telescope projection is also a safe way to observe the eclipse. By using two large, white pieces of card, you can project the eclipse’s image onto one piece, while using the other to fit around your telescope’s tube to act as a mask to shield your eyes from the sun.

'Focusing your telescope’s eyepiece, while holding the second card away, which projects the image, will enable you to show the eclipse to a large group of people safely.

'You should not use a cheap, plastic telescope for telescope projection and ensure that your finderscope has its cap on.

'Never look at the eclipse whilst lining up your telescope with the sun and never leave your telescope unattended. You should also ensure that your instrument doesn’t overheat.'

Can you use household items to view the eclipse? 

'If you don’t have a standard telescope or have forgotten to buy a solar viewer, then there are several household items you can use so that you don’t miss out on seeing this fantastic event.

'Using a piece of card, or anything that has small holes punched into it, you can project the eclipse onto another piece of card. This is certainly one of the safest ways of viewing the eclipse since you don’t need to look at the sun at all.

'A washing up bowl or bucket can also be lined with a black bin liner and then filled with water to make a reflective surface to safely watch the eclipse.

When and where will the eclipse be visible? 

'The eclipse will begin in the morning. For observers in the UK, the eclipse starts at 8.30am, peaks at 9.35 am and ends at 10.41am, so you should make sure that you know where the Sun rises from your location.

'The total solar eclipse - that’s 100 per cent of the Sun’s surface covered by the Moon - is visible from the Faroe Islands and Svalbard but if you are unable to get to these locations, many are able to see a substantial partial eclipse - for instance, Scotland will see around 90 per cent of the Sun’s disc covered by the moon.'

How dark will it get in the UK?

'In London and even in places where there's 90 per cent sun coverage, we're not really going to notice any changes in brightness because there's still a portion of the sun's surface uncovered.

'It'll be like there's a cloud passing over the Sun - you know it's cloudy but it's still light.' 

Observations took place from the Kjell Henriksen Observatory Longyearbyen in Svalbard, pictured. In an amazing coincidence, the eclipse occurred over the North Pole on the same day the sun came into view after six months of polar night - an event which happens only once every 500,000 years.

Observations will take place from the Kjell Henriksen Observatory Longyearbyen in Svalbard, pictured. In an amazing coincidence, the eclipse will occur over the North Pole on the same day the sun comes into view after six months of polar night - an event which happens only once every 500,000 years.

Data and images taken during the eclipse will be used to try and develop a mathematical model to understand this difference in temperature.

'The difference between the temperature of the sun and that of the sun’s corona is one of the great mysteries of astronomy,’ said Dr Huw Morgan, a Reader at the Solar System Physics Group at Aberystwyth University, who is overseeing the team’s work from the UK.

‘A total eclipse gives us an unique opportunity to measure the corona of the sun is so much detail and collect data that will enable us to better understand this difference.' 

The temperature of the sun's surface (shown ion this Nasa image) is known to be around 6,000°C (10,800°F), but for some reason the corona is around 1,000,000°C (1,800,000°F), and even reaches 2,000,000°C (3,600,000°F) in some areas, a factor of about 300

The temperature of the sun's surface (shown ion this Nasa image) is known to be around 6,000°C (10,800°F), but for some reason the corona is around 1,000,000°C (1,800,000°F), and even reaches 2,000,000°C (3,600,000°F) in some areas, a factor of about 300

He also added that studying the corona could help protect satellite-based communication systems from solar storms, which can be affected by coronal mass ejections - huge eruptions of material - from the sun.

But he noted that the conditions were 'cold' - and also potentially dangerous. 

‘All the team have had to do safety training, including polar bear training,’ Dr Morgan told The Guardian.

‘They will have a guard with a rifle. I hope they come back in one piece.’

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