The planetary nebula NGC 40, sometimes referred to as the "Bow tie" nebula, is located in the constellation Cepheus.
NGC 40 was discovered by William Herschel on November 25th, 1788. It is a spectacular object! This planetary lies between a 9th magnitude star 2' to its NE and two 10th magnitude stars 2-3' SW. It is a bright (magnitude 10.7), slightly oval-shaped disk, 48" across, with a conspicuous magnitude 11.5 central star. Brighter areas along the eastern and western edges mimic the appearance of the polar caps of Mars. The western "cap" seems to run off the disk. The "polar cap" effect is only visible on the best of nights.
NGC 40 is composed of hot gas around a dying star. The central star has ejected its outer layer which has left behind a hot, white dwarf core with a surface temperature about 50,000 degrees Celsius; radiation from this star heats the outer layers to about 10,000 degrees.
NGC 40 is about 3,500 light years away, and about one light-year across. About 30,000 years from now, NGC 40 will fade away, leaving only a white dwarf star approximately the size of Earth.