Tripping the light fantastic to the surface of the Sun

Despite having a lousy record for accurately predicting the weather on Earth even a few days ahead, European and American scientists have set themselves a new goal: forecasting the weather on the Sun.

There is a reason for their apparently obscure aim. After a year of careful observation, using the orbiting Soho (Solar and Heliospheric Observatory) spacecraft, they have discovered that the Sun's surface is a churning mass with its own "rivers" of superheated electrically charged gases, or plasma, flowing at a temperature of 5,800C.

The swirling movement of these streams causes sunspots - cooler areas (just 3,800C) on the surface, which show up as dark patches - and solar storms. And these affect the weather, and even communications, on Earth.

Although the Sun's surface temperature seems unimaginable, the temperature is hundreds of times greater at its core, where the energy that powers the star (and in turn, warms the Earth) is produced. There, the immense gravitational forces generated by the mass of the Sun crush together single protons, each one originally the nucleus of an interstellar hydrogen atom, to form a helium nucleus.

Surplus energy is thrown off and eventually reaches us as sunlight. Millions of tons of hydrogen are consumed every second in this process - although the Sun is expected to burn for another 5 billion years or so, being about halfway through its life.

But the light particles (or photons) generated in the fusion process do not stream directly from the heart of the Sun to its surface and then out into space. The core is so dense that the photons must take an atomic Dodgem ride to the surface, bouncing off the atoms in their way as they rush outwards.

Scientists have calculated that it can take a single photon several years to reach the surface of the Sun. From there, however, it enjoys an uninterrupted journey outwards. The tiny proportion which reaches us takes just eight minutes to travel from the Sun's surface to the Earth, 93 million miles (149 kilometres) away.

Long-term variations in the Earth's temperature may be linked to sunspots, while solar storms, which can throw out flares of plasma millions of kilometres into space, can cause radio interference, damage telecommunications satellites and even knock out power stations.

The new data emerged from observations carried out jointly by the European Space Agency (ESA) and Nasa, the United States space agency.

"We have detected motion similar to the weather patterns in the Earth's atmosphere," said Jesper Schou, of Stanford University, California.

The joint European and US team also discovered that the surface of the Sun is slowly moving: the outer layer, to a depth of about 15,000 miles, is flowing at about 50 miles per hour from the Sun's equator to its poles. On that basis, it would take almost two years for any area of plasma to journey from the equator to the poles.

Studying the patterns might make it possible to predict them - giving valuable warnings about looming solar changes.

The observations were carried out by Soho, which is studying the Sun from a spacecraft about 1 million miles from Earth. On board Soho is an instrument which can effectively measure sound waves inside the Sun. "These techniques allow us to peer inside it, much as a doctor can look inside a pregnant woman using ultrasound," Professor Schou said.

The team was astonished to find a complex pattern of streams and currents under the surface. "What we have here is an inroad into understanding the solar cycle, the 11-year cycle of sunspots that has been puzzling us for centuries," said Craig DeForest, of Stanford University.

One stream circles the poles, while a series of others migrates towards the solar equator. By terrestrial standards they are huge: "You can fit almost 100 Earths inside this jetstream," Professor Schou said.

The belts also rub against slower-moving plasma inside the Sun. "That's where the sunspots form," said Professor Douglas Gough, of Cambridge University. The same processes could also underlie solar flares and storms. Last week a flare shot out of the Sun - although scientists say there is no risk to the Earth.

Professor Gough said the streams, which generate huge magnetic and electrical fields, create opposing forces which eventually must find an escape. "Think of them like elastic bands," he said. The bands are twisted and pulled by the motion: "then it slips. It either snaps, or it contracts and shoots out material like a slingshot".

The scientists compared the solar "rivers" to atmospheric currents on Earth. "We are just beginning to understand how the Earth's atmosphere operates," Professor Gough said. "Now we are getting tremendous and interesting details from the Sun."

Professor DeForest said that knowing this could help scientists to predict sunspot activity. "We can predict where on the Sun these things arise."

He compared it to meteorology - which allows prediction of general weather patterns, but not of localised events. In the same way, the Soho findings will make it easier to predict trends, but it will not be possible to predict where an individual sunspot will arise - "just like it's not easy to predict where a thunderstorm will break out".

However, knowing the right area might add a few days to the warnings that are now given when a solar storm is coming. And that, in turn, could mean an easier time back on Earth - even if it is raining.

Heat and dust: A solar flare pushes out from the surface of the Sun, as recorded by Soho, the European/United States Solar and Heliospheric Observatory, 1 million miles from Earth

Bottom left, solar rotation rate with depth: The (false) colours represent speed; red material is rotating the fastest and dark blue the slowest. The left side of the figure shows rotation speed at the surface of the Sun. Red material at the equator is moving approximately 3,000 miles per hour faster than the blue material at the poles. The cutaway reveals rotation speed inside the Sun. The large dark-red bank is a massive fast flow of hot, electrically charged gas called plasma, beneath the solar equator

Bottom centre, variations in solar motion: This image represents the difference in speeds of areas on the surface and in the interior of the Sun. Red and yellow are faster than average, and blue is slower. The cutaway reveals speed variations in the interior. The red ovals embedded in the green areas at the poles are the newly discovered polar plasma "jet streams", each large enough to engulf two Earths

Bottom right, polar flows: The flow lines, showing the surface flow from the equator to the poles, are set over an image of the rotation speed at the surface. The cutaway represents the observed polar flow 15,000 miles beneath the surface and a hypothetical return flow 120,000 miles under the surface Photographs: Nasa

Start your day with The Independent, sign up for daily news emails
Have you tried new the Independent Digital Edition apps?
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Business Analyst - 12 Month FTC - Entry Level

£23000 - £27000 per annum: Recruitment Genius: A Business Analyst is required ...

Recruitment Genius: Chefs - All Levels

£16000 - £23000 per annum: Recruitment Genius: To succeed, you will need to ha...

Recruitment Genius: Maintenance Engineer

£8 per hour: Recruitment Genius: This is an opportunity to join an award winni...

Recruitment Genius: Telesales Executive & Customer Service - Call Centre Jobs!

£7 - £9 per hour: Recruitment Genius: Are you outgoing? Do you want to work in...

Day In a Page

Isis in Syria: Influential tribal leaders hold secret talks with Western powers and Gulf states over possibility of mobilising against militants

Tribal gathering

Influential clans in Syria have held secret talks with Western powers and Gulf states over the possibility of mobilising against Isis. But they are determined not to be pitted against each other
Gaza, a year on from Operation Protective Edge: A growing population and a compromised and depleted aquifer leaves water in scarce supply for Palestinians

Gaza, a year on from Operation Protective Edge

A growing population and a compromised and depleted aquifer leaves water in scarce supply for Palestinians
10 best trays

Get carried away with 10 best trays

Serve with ceremony on a tray chic carrier
Greece debt crisis: EU 'family' needs to forgive rather than punish an impoverished state

EU 'family' needs to forgive rather than punish an impoverished state

An outbreak of malaria in Greece four years ago helps us understand the crisis, says Robert Fisk
Gaza, a year on from Operation Protective Edge: The traumatised kibbutz on Israel's front line, still recovering from last summer's war with Hamas

Gaza, a year on from Operation Protective Edge

The traumatised kibbutz on Israel's front line, still recovering from last summer's war with Hamas
How to survive electrical storms: What are the chances of being hit by lightning?

Heavy weather

What are the chances of being hit by lightning?
World Bodypainting Festival 2015: Bizarre and brilliant photos celebrate 'the body as art'

World Bodypainting Festival 2015

Bizarre and brilliant photos celebrate 'the body as art'
alt-j: A private jet, a Mercury Prize and Latitude headliners

Don't call us nerds

Craig Mclean meets alt-j - the math-folk act who are flying high
How to find gold: The Californian badlands, digging out crevasses and sifting sludge

How to find gold

Steve Boggan finds himself in the Californian badlands, digging out crevasses and sifting sludge
Singing accents: From Herman's Hermits and David Bowie to Alesha Dixon

Not born in the USA

Lay off Alesha Dixon: songs sound better in US accents, even our national anthem
10 best balsamic vinegars

10 best balsamic vinegars

Drizzle it over salad, enjoy it with ciabatta, marinate vegetables, or use it to add depth to a sauce - this versatile staple is a cook's best friend
Wimbledon 2015: Brief glimpses of the old Venus but Williams sisters' epic wars belong to history

Brief glimpses of the old Venus but Williams sisters' epic wars belong to history

Serena dispatched her elder sister 6-4, 6-3 in eight minutes more than an hour
Greece says 'No': A night of huge celebrations in Athens as voters decisively back Tsipras and his anti-austerity stance in historic referendum

Greece referendum

Greeks say 'No' to austerity and plunge Europe into crisis
Ten years after the 7/7 terror attacks, is Britain an altered state?

7/7 bombings anniversary

Ten years after the terror attacks, is Britain an altered state?
Beautiful evening dresses are some of the loveliest Donatella has created

Versace haute couture review

Beautiful evening dresses are some of the loveliest Donatella has ever created