Cycle 24 - time to panic

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Nugget
Number: 99
1st Author: Leif Svalgaard
2nd Author: and Hugh Hudson
Published: 13 April 2009
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Contents

Introduction

We're in an extended period of minimal solar activity (see Nugget 91 for a previous look at this issue - without flares, RHESSI is missing its most important observational work, and there has not been even a C-class flare yet this year. Will sunspots and flares ever return? How unusual is this behavior? In this Nugget we conclude that it is too soon to panic, but that certainly we're seeing an unusually diminished level of activity.

F10.7 and other indices

'Figure 1: The F10.7 index for the last 24 months (red) and the average variation, month by month since the peak of the corresponding maximum, for the four previous cycles in the record.
'Figure 2: Three key indices of solar activity, showing the current minimum period from 2008 to the time of writing (April 11, 2009).

This plot comes from a Web page that is updated daily.


daily view

Counting the new and old spots

Historical fact

Conclusions

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