Some Thoughts on the Sun's Recent Outbursts

on Sun, 2 Nov 2003 18:45:39 GMT, Henry Spencer sez:
` In article ,
` Bruce Hoult wrote:
` How many cycles have we actually observed, anyway, to be so sure of this
` 11 year cycle? I wasn't yet around at the time, but I thought it was
` only discovered in the 50's?

` While we have detailed solar data only from the last half-century or so,
` the 11-year cycle of sunspot activity was discovered in 1843, and there is
` usable historical data from somewhat before that.

Cycles can also be detected in isotope ratios in ice cores, which,
while admittedly rather secondary evidence, can be argued to be
due to solar activity, somewhat convincingly as they line up for
the cycles we do have independent data for. Not sure how far
back these have been mapped, but it's quite a ways...


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Pete Vincent
Disclaimer: all I know I learned from reading Usenet.

Allen Thomson wrote:
Bruce Hoult wrote


How many cycles have we actually observed, anyway, to be so sure of this
11 year cycle? I wasn't yet around at the time, but I thought it was
only discovered in the 50's?


We're pretty sure about it, because useable observations go back a few
centuries:

Have similar cycles been observed on other stars?

In article ,
Ian Stirling wrote:
We're pretty sure about it, because useable observations go back a few
centuries:

Have similar cycles been observed on other stars?

Yes, although less directly since we can't actually resolve sunspots
on them.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |