Hubble has revealed the true shape of the nebula, the glowing gas shroud around an old, dying, sun-like star, the space agency reported Thursday.
The nebula's apparent ring shape is a result of perspective but the Hubble images show a more complex structure than astronomers once thought and have allowed them to construct the most precise 3-D model of the nebula.
The nebula appears to be a ring because the view from Earth is looking straight into what is actually a barrel-shaped cloud of gas, astronomers said.
"The nebula is not like a bagel, but rather, it's like a jelly doughnut, because it's filled with material in the middle," C. Robert O'Dell of Vanderbilt University in Nashville, said.
O'Dell leads a research team that used Hubble and several ground-based telescopes to obtain the best view yet of the iconic nebula.
It will continue to expand for 10,000 years, a short phase in the lifetime of the star, the astronomers said, then will become fainter and fainter until it merges with the interstellar medium.