NGC 2392：双层的行星状星云
2020 February 16 NGC 2392: Double-Shelled Planetary Nebula Image Credit: NASA, ESA, Hubble, Chandra; Processing & License: Judy Schmidt Explanation: To some, this huge nebula resembles a person’s head surrounded by a parka hood. In 1787, astronomer William Herschel discovered this unusual planetary nebula: NGC 2392. More recently, the Hubble Space ...