APOD: 2026 January 23 - Planetary Nebula Abell 7

Good Red Friday morning, Rallypoint, and welcome to the January 23, 2026 edition of Astronomy Picture of the Day (APOD).

There are generally four classes of nebulae: H II (read "H 2") regions, supernova remnants, dark nebulae, and planetary nebulae. A H II region is an area of ionized hydrogen gas. We saw an example of a dark nebula yesterday (e.g. LDN 1622). Researchers believe that a planetary nebula forms as a star of intermediate mass (like our Sun) reaches the end of its life. The term originates from the planet-like round shape of these nebulae observed by astronomers through early (18th century) telescopes.

The first documented use of the term "planetary nebula" was in January 1779, when French astronomer Antoine Darquier de Pellepoix described the Ring Nebula (M57) as "very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". Though the modern interpretation is different, the old term is still used.

Abell 7 was first noted by American astronomer George Abell in 1955. It is 1,800 light years away and located in the constellation Lepus (The Hare). APOD has featured Abell 7 since 2013.