... Credit Copyright: Daniel L pez , IAC Explanation: NGC 2438 is a planetary nebula , the gaseous shroud cast off by a dying sunlike star billions of years old whose central reservoir of hydrogen fuel has been exhausted. ... Remarkably, NGC 2438 also seems to lie on the outskirts of bright, relatively young open star cluster M46 . ... This deep image of NGC 2438 highlights a previously unseen halo of glowing atomic gas over 4.5 light-years across, extending beyond the nebula's brighter inner ring. ...