👁️ Image of the Month: zoom into the cosmic eye

For this ESA/Hubble Image of the Month, the Hubble Telescope teams up with ESA's Euclid to offer a new view of the visually most complex remnants of a dying star known as the Cat's Eye Nebula, first discovered in 1864 and located about 4,300 light-years from Earth.

Although Euclid is primarily designed to map the distant Universe, it observed the Cat's Eye Nebula as part of its deep imaging surveys.


In the wide-field image obtained by the Euclid space telescope, observing in visible and near-infrared light, the Cat's Eye Nebula appears surrounded by an extended halo of gas ejected by the central star during successive phases of mass loss. These structures correspond to layers of matter expelled during the final stages of stellar evolution.

The observation over such a wide field also reveals numerous very distant galaxies in the background. Their presence is a reminder that modern astronomical surveys allow the simultaneous study of stellar evolution processes in our Galaxy and the distribution of galaxies on a cosmic scale.

Two image processing specialists, Jean-Charles Cuillandre and Emmanuel Bertin, both astronomers at the Observatoire des Sciences de l'Univers de Paris-Saclay and members of the Department of Astrophysics at CEA Irfu, produced this image. Its production is part of the science communication efforts led by ESA and the Euclid Consortium, to accompany the key milestones of the Euclid mission and its large sky survey.

The nebula is highlighted thanks to the combined views of the Hubble Space Telescope (NASA/ESA) and Euclid (ESA), revealing the remarkable complexity of stellar death.


The image on the left, from combined observations by the Euclid and Hubble Space Telescopes, shows the Cat's Eye Nebula and the vast envelope of gas surrounding it. This material comes from the outer layers of a Sun-like star, expelled when it entered the final phase of its evolution. During this stage, the star gradually loses its envelope through stellar winds, forming an extended halo of gas around it.

The white box indicates the central region of the nebula, shown in detail in the image on the right obtained by Hubble. It shows several nested shells and bubbles of gas, shaped when fast stellar winds collided with layers of matter ejected earlier. The intense radiation from the central star heats and ionizes this gas, causing it to glow and revealing the complex structure of this planetary nebula, a brief stage in a star's evolution before it becomes a white dwarf.