Scientists Warn Sun Will “Go to Sleep” in 2030, Could Cause Temperatures to Plummet
Around 500 astronomers and space scientists gathered at Venue Cymru in Llandudno, Wales, from 5-9 July, for the Royal Astronomical Society National Astronomy Meeting 2015 (NAM2015, Cyfarfod Seryddiaeth Cenedlaethol 2015). The conference is the largest regular professional astronomy event in the UK and saw leading researchers from around the world presenting the latest work in a variety of fields. Science writer and editor Kulvinder Singh Chadha presents his fourth and final report from the last day of the event:
The two-hearted Sun beckons new ‘mini ice-age’
Like the enigmatic, eponymous character from Doctor Who our Sun may have two hearts. A new model of the Sun’s interior is producing predictions of its behaviour with unprecedented accuracy; predictions with interesting consequences for Earth. Professor Valentina Zharkova of Northumbria University presented results for a new model of the Sun’s interior dynamo in a talk at NAM2015.
Our Sun has an approximately 11-year activity cycle. During peak periods, it exhibits lots of solar flares and sunspots. Magnetic bubbles of charged particles (coronal mass ejections) may burst from the surface during this period, streaming material into space. These ejections can affect satellites and powerlines on Earth. During lull periods, such activity may almost stop altogether. But the 11-year cycle isn’t quite able to predict all of the Sun’s behaviour — which can seem erratic at times. Zharkova and her colleagues (Professor Simon Shepherd of Bradford University, Dr Helen Popova of Lomonosov Moscow State University, and Dr Sergei Zarkhov of Hull University) have found a way to account for the discrepancies: a ‘double dynamo’ system.
The Sun, like all stars, is a large nuclear fusion reactor that generates powerful magnetic fields, similar to a dynamo. The model developed by Zharkova’s team suggests there are two dynamos at work in the Sun; one close to the surface and one deep within the convection zone. They found this dual dynamo system could explain aspects of the solar cycle with much greater accuracy than before — possibly leading to enhanced predictions of future solar behaviour. “We found magnetic wave components appearing in pairs; originating in two different layers in the Sun’s interior. They both have a frequency of approximately 11 years, although this frequency is slightly different [for both] and they are offset in time,” says Zharkova. The two magnetic waves either reinforce one another to produce high activity or cancel out to create lull periods.
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