'Something unexpected' is happening on the Sun, Nasa has warned.
This year was supposed to be the year of 'solar maximum,' the peak of the 11-year sunspot cycle.
But as this image reveals, solar activity is relatively low.
'Sunspot numbers are well below their values from 2011, and strong solar flares have been infrequent,' the space agency says.
The image above shows the Earth-facing surface of the Sun on February 28, 2013, as observed by the Helioseismic and Magnetic Imager (HMI) on NASA's Solar Dynamics Observatory.
It observed just a few small sunspots on an otherwise clean face, which is usually riddled with many spots during peak solar activity.
Experts have been baffled by the apparent lack of activity - with many wondering if NASA simply got it wrong.