NGC 1535 — Planetary Nebula in Eridanus

NGC 1535, often called Cleopatra's Eye, is a small but visually striking planetary nebula in Eridanus, about 5,000 light-years away. It shows a clear two-shell structure in any decent telescope: a bright inner disc surrounding the central star, embedded in a fainter outer halo. The colour is a pronounced blue-green from doubly-ionized oxygen emission, similar in tone to the Eskimo Nebula and the Blue Snowball but with a more sharply defined boundary. At magnitude 9.6 with about 50 arcseconds across, NGC 1535 has high surface brightness and takes magnification very well.

An ideal small-telescope target. A 4-inch at 200x shows a well-defined small disc with a noticeable blue-green tint. An 8-inch at 300-400x reveals the two-shell structure clearly, the outer halo extending beyond the bright inner disc. The central star (about magnitude 12) is a glimmering challenge in 12-inch and larger scopes from steady skies. The high contrast between the bright disc and the dark sky lets you push the magnification harder than with most planetaries. Best observed November through March.

Discovered by William Herschel on 1 February 1785. The 'Cleopatra's Eye' nickname is a 20th-century invention that captures its almond-shape look in deep imaging.