Sun's Solar Activity Is Weakest In A Century

Despite being at the peak of it's 11-year cycle, the Sun is at its weakest in 100 years.

Feeble solar activity has meant storms on the star's surface and coronal mass ejections (CMEs) have lacked any kind of punch.

Usually, particularly powerful CMEs can knock out satellites and disrupt power and communications on Earth but - perhaps thankfully - recent activity has had little effect.

A solar flare pictured in 2012

Leif Svalgaard of Stanford University, said: "None of us alive have ever seen such a weak cycle. So we will learn something."

Scientists believe the phenomenon is due to a decrease in pressure in the heliosphere - a kind of vast bubble surrounding the Sun reaching beyond Pluto and maintained by solar winds.

This decrease allows CMEs to expand more as they travel through space.

Nat Gopalswamy of NASA's Goddard Space Flight Centre, said: "When the CMEs expand more, the magnetic field inside the CMEs has lower strength.

"So when you have lower-strength magnetic fields, then they cause milder geomagnetic storms."

The Sun's magnetic field is currently in the process of flipping with the polarity of sunspots changing.