Astronomy Picture of the Day

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 Telescope imaged the nebula in visible light, The featured image of the nebula shows gas clouds so complex they are not fully understood. NGC 2392 is a double-shelled planetary nebula, with the more distant gas having composed the outer layers of a Sun-like star only 10,000 years ago. The outer shell contains unusual light-year long orange filaments. The inner filaments visible are being ejected by strong wind of particles from the central star. The NGC 2392 Nebula spans about 1/3 of a light year and lies in our Milky Way Galaxy, about 3,000 light years distant, toward the constellation of the Twins (Gemini).