Simeis 147 is a supernova remnant spanning over 3 degrees of the sky. It's estimated to lie about 3000 light years from Earth, have an approximate diameter of 165 light years across, and an expansion rate of nearly 600 miles per second. The violent stellar explosion that created this object occurred about 30,000 years ago, leaving behind beautiful wisps of material and a pulsar designated PSR J0538+2817.