"Something unexpected is happening on the Sun. 2013 was supposed to be the year of 'solar maximum,' the peak of the 11-year sunspot cycle. Yet 2013 has arrived and solar activity is relatively low. Sunspot numbers are well below their values from 2011, and strong solar flares have been infrequent," the space agency wrote in a statement.
The above picture, taken on Feb. 28, shows the surface of the Sun facing the Earth. You'll notice there are only few visible sunspots (those black dots on the lower half of the sun). Typically the sun would be covered in these spots coinciding with the active phase of its solar peak, NASA says.