Euclid e Hubble insieme per la nebulosa Occhio di Gatto

For this month’s ESA/Hubble Picture of the Month, we turn our gaze to one of the most visually intricate remnants of a dying star: the Cat’s Eye Nebula, also known as NGC 6543. This extraordinary planetary nebula has captivated astronomers for decades with its elaborate and multilayered structure. Observations with ESA’s Gaia mission place the nebula at a distance of 4 400 light years away. Planetary nebulae, so-called because of their round shape when viewed through early telescopes, are in fact expanding gas thrown off by stars in their final stages of evolution. It was the Cat’s Eye Nebula itself where this fact was first discovered in 1864 — examining the spectrum of its light reveals the emission from individual molecules that’s characteristic of a gas, distinguishing planetary nebulae from stars and galaxies. The NASA/ESA Hubble Space Telescope also revolutionised our understanding of planetary nebulae; its detailed images showed that the simple, circular appearance of a planetary nebula seen from the ground belies a very complex morphology. This was particularly true of the Cat’s Eye Nebula, where Hubble’s images in 1995 revealed never-before-seen structures that broadened our understanding of how planetary nebulae come to be. In this new image, Hubble captures the very core of the billowing gas with the High Resolution Channel sub-instrument on its Advanced Camera for Surveys (ACS). This instrument is optimised for capturing very sharp images of fine details in a small area, such as the complex features at the heart of the Cat’s Eye Nebula. The data reveal a tapestry of concentric shells, jets of high-speed gas and dense knots sculpted by shock interactions, features that appear almost surreal in their intricacy. These structures are believed to record episodic mass loss from the dying star at the nebula’s centre, creating a kind of cosmic “fossil record” of its final evolutionary stages. Part of these data were also used in a previo