re: Yo, R.L. -- and Nick . . .
Yes, the sunspot record for solar observations are merely a few hundred years old, but, from Tom's post:
Sunspot observations stretch back to the early 17th century, when the telescope was invented. To extend the data farther back in time, Usoskin's team used a physical model to calculate past sunspot numbers from levels of a radioactive isotope preserved in ice cores taken from Greenland and Antarctica.
Didn't know about the 1800's sighting. Were auroras recently seen as far south as Hawaii? Last I heard was last weeks, where they were expected to extend as far south as Florida.
And how does our Borealis-counter look down Australia-way? Admittedly, I haven't been checking. Know of any good pics out there, Nick?
Cheers,
Dan