20 Euros Cat's Eye Nebula

The Cat's Eye Nebula (NGC 6543) was among the first objects examined spectroscopically by William Huggins in 1864, confirming that nebulae could consist of luminous gas rather than unresolved stars — a result that fundamentally redirected nineteenth-century astronomy. Austria's ongoing "Beauties of the Universe" silver program has drawn consistently from objects with strong observational histories, and NGC 6543 fits that pattern precisely. Hubble imaging in the 1990s revealed its concentric shell structure to be far more complex than ground-based observation had suggested, with at least eleven nested rings of expelled stellar material.