If you think the sun stays the same size all the time, think again. Scientists have found that when the sun is at its most active, it shrinks!
The sun is a massive, swirling ball of gas and energy. This energy generates an area of attractive and repulsive forces called a magnetic field. This field changes strength throughout the solar cycle, an 11-year pattern when the sun’s energy and magnetic field ebb and flow. When the magnetic field is at its strongest, it pulls the sun inward. This pull causes the giant ball of gas to shrink 1 to 2 kilometers.
The radius of the sun is 695,660 kilometers. But even a 1 kilometer change is important, says Alexander Kosovichev, a physicist from the New Jersey Institute of Technology. We don’t fully understand the sun’s solar cycle, he says. So every kilometer of data helps!