These comet-like objects came into view as O'Dell used Hubble's Wide Field Planetary Camera 2 to survey the Helix nebula, located 450 light-years away in the constellation Aquarius and the closest planetary nebula to Earth -- so close that its angular size is almost half that of the full Moon.
The most visible cometary knots all lie along the inner edge of the ring, at a distance of trillions of miles from the central star. Their comet-like tails, each stretching a hundred billion miles, form a radial pattern around the star like the spokes on a wagon wheel.
The knots have just the right appearance and are at just the right distance from the dying star to be a long-sought comet cloud, much like the hypothesized Oort cloud encircling our solar system. However, each gaseous cometary "head" is at least twice the diameter of our solar system.
The left image shows the location of the area studied. The photograph on the right shows a detail.
HUBBLE FINDS THOUSANDS OF GASEOUS FRAGMENTS
SURROUNDING DYING STAR
(R. Villard. 15-4-1996)