Earth's closest star 'dimmest it's been for a century'
The sun is the dimmest it has been for almost a century, scientists say.
Leading astronomers admit they are baffled why the Earth's closest star has gone so quiet - and when it will burst back into life.
The sun normally goes through an 11-year cycle of activity. At its peak - a period known as the solar maximum - the sun is covered with dozens of sun spots as it spits out vast flares and balls of superheated gas the size of planets.
At the other end of the cycle, during the solar minimum, it is calm with relatively few sun spots and few eruptions. Last year, scientists assumed the sun was about to become more active after a quiet few years.
But instead it has hit a 100-year low in sunspot activity, a 50-year low in solar wind pressure and a 55-year low in radio emissions. The observations have intrigued astronomers who are studying new images at the UK National Astronomy Meeting this week.
Natural cycles of the sun directly affect our climate. Between 1645 and 1710, the sun went through an unusually quiet spell which some believe triggered a mini Ice Age.
Some climate change sceptics have claimed the warming of the Earth in the last 100 years is the result of solar activity. However, studies have shown the sun's activity has been decreasing since 1985 while the Earth's temperature has risen sharply.
Most climate scientists believe the rise in temperatures since the 1970s is likely to be caused by the release of greenhouse gases which trap heat around the Earth.
Dr Jim Wild, of Lancaster University, said: 'Over the last couple of years the sun has been getting dimmer. In terms of visible brightness it is an incredibly small drop. But in terms of extreme ultraviolet radiation, it has dropped by a few per cent.
'The accepted view is solar brightness has some effect on climate, but it looks like the sun has been dimming.
'Despite that we are still seeing temperatures increase in general. This is not going to save us from climate change.'
The sunspot cycle is driven by the movement of complex magnetic fields.
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