The Helix Nebula [NGC 7293] was discovered by the German astronomer, Karl Ludwig Harding (1765 - 1834), probably before 1824. Located in the constellation Aquarius, it is one of the closest planetary nebulas to Earth. It is believed that the remnant of the central stellar core, or planetary nebula nucleus (PNN), will become a white dwarf star. The PNN is so energetic that the expelled, and expanding, gases fluoresce. The nebula is 2.5 light-years across, with the outer ring expanding at about 40 km/s, and the inner at 32 km/s.
Type: Planetary nebula
Designations: NGC 7293, Caldwell 63
Visual magnitude: 7.6v
Estimated age: 10,600 (+2,300, or -1,200) years
Distance from Earth: 694.7 light-years