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Frozen cosmic fingerprints

Researchers claim to find evidence of 11th century supernovas and the solar cycle in an ice core

Analyzing the composition of an Antarctic ice core, Japanese researchers say they have found the chemical fingerprints of two well-known supernovas from the 11th century, as well as evidence of an 11-year solar cycle from the same century.  

“This is one of the first times that a distinct 11-year solar cycle has been observed for a period before the landmark studies of sunspots by Galileo Galilei with his telescope,” Yuko Motizuki of the RIKEN Nishina Center for Accelerator-Based Science in Wako, Japan, and his colleagues assert in an article posted online February 20 ( The findings, the team adds, “have significant consequences” for dating ice cores, discovering previously unknown supernovas in the Milky Way and revealing the history of the solar cycle.

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