The Sun’s Sleepy Phase Is Surprisingly Consistent | Space
Sixty years of data reveal that, while the maximum level of solar activity can vary drastically, one measure indicates it always returns to the same quiet minimum.
The sun goes through an 11-year cycle of activity — at maximum, there are more sunspots and solar action as the sun’s magnetic field curls and twists, sending charged particles flying out (sometimes toward Earth). At minimum, the sun’s face is smooth, with fewer sunspots and less activity.
The sun’s activity is also reflected in the amount of microwave radiation it releases — and that microwave level and the specific bands of radiation released have remained the same during the past five solar minimums, according to new research. [Take the Sun Quiz! Test Your Solar Smarts]
Researchers began continuously monitoring the sun’s microwaves in 1957, using a telescope at the Toyokawa Branch of Nagoya University in Japan, according to a statement describing the new work. That telescope was relocated to the National Astronomical Observatory of Japan’s (NAOJ) Nobeyama campus in 1994, but it has kept its sensors fixed on the sun.