Scientists at the University of Warwick and the University of Durham in England have linked the very first historical illustration of sunspots, recorded in Medieval England in 1182, with the appearance of the aurora borealis 5 days later in Korea.
Professor F. Richard Stephenson, Department of Physics, University of Durham, was the first astronomer to discuss the earliest known drawing of sunspots, which appears in The Chronicle of John of Worcester and predates the invention of the telescope by almost 500 years.
This medieval chronicle, which covers the historical period from earliest times to AD 1140, contains a number of records of celestial phenomena. These include aurorae, comets and meteor showers, as well as eclipses of the Sun and Moon.
One of the most interesting of these reports is a description of two sunspots that were seen on December 8 in AD 1128 from Worcester in England. In the manuscript that contains this account, the Latin text is accompanied by a colorful drawing that shows two large sunspots on the face of the Sun. This drawing appears to be the earliest known illustration of sunspots.
Sunspots were recorded in China more than 1,000 years beforehand, but no Chinese drawing depicting discrete solar spots exists until about AD 1400, and no subsequent illustration of sunspots survives until after the invention of the telescope almost 200 years later.
Dr. David M. Willis, Space and Astrophysics Group, Department of Physics, University of Warwick, noted that the scientific importance of this observation of two sunspots on December 8 in AD 1128 is increased by an observation of the aurora borealis (northern lights) recorded in Korea only five days after the sunspots, on December 13.
This observation of a red light in the nighttime sky from Songdo (the modern city of Kaesong) was recorded in the Koryo-sa, the official Korean chronicle of the time.
A delay of five days is typical of the average delay between the occurrence of a large sunspot group near the center of the Sun's face and the subsequent appearance of the aurora borealis in the night sky at relatively low latitudes. Observations of this type help scientists to understand how solar activity has changed over historical time.
[Contact: Dr. David M. Willis, Professor F. Richard Stephenson, Peter Dunn]