Over four hundred years ago, famed astronomer Johannes Kepler witnessed a bright new star light up the sky which, unbeknownst to him, was actually the remnants of a star that had exploded tens of thousands of years prior. But the supernova's remains are still active to this day, and scientists have been able to use a specially designed X-ray telescope at the Chandra observatory to monitor its activity. After more than 200 hours of observation in 2006, a composite image of Kepler's lingering form has been created, showing the varying energy levels of its X-ray emissions. If you're concerned about the effects that Kepler's stellar explosion may have on our planet, worry not — the remnants are estimated to be at least 16,000 light years away.