For instance, the years 1947 and 1957 were both periods of sunspot maximum as well as being monumental UFO years.

He found that a significant percent of what he classified as the most important historical events involving large numbers of people occurred around sunspot maximum.

Therefore, the atmospheric C concentration is lower during sunspot maxima and higher during sunspot minima.

There seems to be a positive correlation between sunspot maximum and Es activity in Europe.

The sun was at sunspot maximum and static had drowned out all attempts.

It was essential, he had argued forcibly, to get his equipment installed before the peak of the current sunspot maximum.

Both forms of degradation follow the 11 year solar cycle and are a maximum at sunspot maximum although they can occur at anytime.

It had been guessed that those changes on the planet where humanity began had been caused by a coincidence of sunspot maxima.

This normally occurs close to sunspot maximum, when solar activity increases ionization levels in the upper atmosphere.

He was only seventy million miles from the sun during a period of sunspot maximum.