A typical day for Professor David
The Wolf sunspot number
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When the clouds are gone, the professor David can
finally draw the Sunspots. Indeed
the SIDC
at the ROB, day after day observe,
count and follow the evolution of the different Sunspots, thus
producing a variable
called the "Wolf Sunspot number". Our department has been providing the
observatory with daily
observations of the photospheric solar disk for thirty years. The
observation consists
in drawing the position of Sunspots and groups of spots on the
cardboard. The Wolf Sunspot
number is calculated by multiplying by ten the number of groups and
adding to it
the number of Sunspots. The Wolf number varies in a periodical way
during a cycle of 11 years,
ranging between 0 and 150 (or more) according to the intensity of the
solar activity. One can see here the scientist in action, who starts drawing the Sunspots and the plages on the cardboard. This work requires lots of patience and precision. |
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