Solar minimum surprisingly constant
More than half a century of observation yields new discovery
NATIONAL INSTITUTES OF NATURAL SCIENCES
Using more than half a century of observations, Japanese astronomers have discovered that the microwaves coming from the Sun at the minimums of the past five solar cycles have been the same each time, despite large differences in the maximums of the cycles.
Solar microwave observation telescopes in 1957 (top left) and today (bottom left). Fluctuations observed during 60 years of solar microwave monitoring (top right) and the solar microwave spectrum at each solar minimum (bottom right). The background is full solar disk images taken by the X-ray telescope aboard the Hinode satellite. CREDIT NAOJ/Nagoya University/JAXA
In Japan, continuous four-frequency solar microwave observations (1, 2, 3.75 and 9.4 GHz) began in 1957 at the Toyokawa Branch of the Research Institute of Atmospherics, Nagoya University. In 1994 the telescopes were relocated to…
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