February 19 is the birth anniversary of Renaissance-era mathematician and astronomer Nicoalus Copernicus. I wrote an article summarizing his life earlier this afternoon for my A Stamp A Day blog and then remembered I had one Copernicus-related postcard. The card pictures Copernicus’s heliocentric diagram of the Solar System presented in a work published shortly before his death in May 1543. He was born in 1473 … Continue reading Copernicus’s Toruń