The Eye Nebula (NGC 6656) is not measured in light-years. Light-years are a measure of distance, while the Eye Nebula is a planetary nebula, which is a cloud of gas and dust ejected from a dying star.

Here's why we don't measure it in light-years:

* Size: The Eye Nebula is relatively small compared to the vast distances measured in light-years. It spans a few light-months across, not years.

* Not a distance: Planetary nebulae are objects within our galaxy, not points of light so distant that we measure them in light-years.

Instead, we describe its size in astronomical units (AU). One AU is the average distance between the Earth and the Sun. The Eye Nebula has a diameter of about 0.8 light-years, which is about 50,000 AU.