The Cat's Eye planetary nebula is located about 4,400 light-years away, in the constellation Draco, and is one of the best-known—but also one of the most complex—nebulae of this type. This new, composite image of the nebula was created using the Hubble and Euclid space telescopes.
In general, planetary nebulae form during the final stages of the lives of stars with masses similar to that of the Sun. In other words, when the hydrogen in the core of such a star is converted into helium, its outer layers expand significantly, and as its surface temperature decreases, the visible light it emits shifts toward the red end of the spectrum. In the final stages of its life, the star becomes a red giant. However, it does not remain at this stage for long. When the helium in its core is converted into carbon and oxygen, the nuclear reactions will cease forever. The star will then eject its outer layers into space, forming an expanding cloud of gas and revealing its superheated core, which has been compressed into a white dwarf.
Euclid's images in the near-infrared and visible light reveal a halo of gas moving away from the bright central region of the nebula. This ring of gaseous material was ejected from the nebula’s parent star at an earlier stage—that is, before the main nebula we see in the center formed.
The Hubble Space Telescope, on the other hand, focused on the nebula’s core, revealing a highly complex structure consisting of multiple layers of gaseous material, filamentary structures, and denser knots—suggesting that the parent star did not eject its material in a single burst, but in several more “outbursts” over the course of thousands of years.
Credit: ESA/Hubble & NASA, ESA Euclid/Euclid Consortium/NASA/Q1-2025, J.-C. Cuillandre & E. Bertin (CEA Paris-Saclay), Z. Tsvetanov