How we solved a centuries-old mystery by discovering a rare form of star collision
(PHYSorg.com Space & Earth)

A bright new star appeared in the sky in June, 1670. It was seen by the Carthusian monk Père Dom Anthelme in Dijon, France, and astronomer Johannes Hevelius in Gdansk, Poland. Over the next few months, it slowly faded to invisibility. But in March 1671, it reappeared - now even more luminous and among the 100 brightest stars in the sky. Again it faded, and by the end of the summer it was gone. Then in 1672, it put in a third appearance, now only barely visible to the naked eye. After a few months it was gone again and hasn`t been seen since.