You are here

Rudolf Wolf

July 7, 2016

The Sun has been exceptionally quiet for most of this year, with few sunspots marking its surface. In fact, the number of sunspots peaked more than two years ago. It’ll probably bottom out in about three more years — completing another cycle of magnetic activity.

The man who was the first to precisely plot the solar cycle was born 200 years ago today. Rudolf Wolf was born in Switzerland, and became one of Europe’s leading astronomers.

In the 1840s, Wolf became fascinated with the findings of another astronomer, who’d spent years counting sunspots. He found that the number of spots seemed to vary over a period of about a decade.

Wolf began counting sunspots himself — something he did for almost half a century. He also tracked down records of sunspots as far back as 1610. From that, he found that, on average, the number of sunspots peaked every 11 years. And later, Wolf was one of several astronomers to notice a link between spots on the Sun and auroras and other magnetic events on Earth.

At first, colleagues belittled Wolf’s idea of a solar cycle. But Wolf was able to stand behind his claims in part because he was an expert on statistics and probability, so he knew the numbers were solid.

The objections have long since melted away. Today, the sunspot cycle is much better understood. It reaches a peak when the Sun’s magnetic field becomes twisted and tangled, creating dark storms on the surface — storms that peak roughly every 11 years.

Script by Damond Benningfield

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.