Add Yahoo as a preferred source to see more of our stories on Google. The Sun's activity levels fluctuate on an 11-year cycle. (Javier Zayas Photography/Moment/Getty ...

Scientists decode Johannes Kepler’s 417-year-old sunspot drawings, solving a long-standing mystery about solar cycles and the ...

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. These processes follow the ...

During strong cycles, the sun’s total brightness at the solar maximum is about 0.1% higher than during its solar minimum, but when averaged out over the industrial period, the sun’s total brightness ...

In 1607, Johannes Kepler projected an image of the Sun onto a piece of paper and spotted a dark smudge. He thought he was ...