Explanation:  The Helix Nebula (New General Catalogue n. 7293) at 450 light years away from the Sun, in the direction of the constellation Aquarius, turns out to be one of the dying stars closest to the sun. The mass of the star progenitor is not sufficient to trigger explosive events that would lead to a dramatic death as a supernova, it only lose the most rarefied outer layers that are illuminated from the star center, in a sort of stellar decomposition. The angular size (or the one apparent in the sky) is equal to approximately half that of the full moon while the current actual dimensions whereas the cloud structure is expanding at a speed of tens of kilometers per second extends for about 1.5 years light. Due to its shape is also called Helix nebula.