A September 30, 2026 edition of Astronomy Picture of the Day featured a detailed portrait of the peculiar spiral galaxy Arp 78, also known as NGC 772, located within the constellation Aries. The image credit goes to Robert Eder.

According to the accompanying explanation, the galaxy lies some 100 million light-years beyond the stars and nebulae of the Milky Way and spans an enormous 200,000 light-years. Its prominent outer spiral arm, traced by sweeping dust lanes and lined with young blue star clusters, appears overdeveloped and is thought to be amplified by galactic-scale gravitational tides. Interactions with its brightest companion, the more compact NGC 770, likely drive this effect. NGC 770 appears directly below the larger spiral as a fuzzy elliptical object embedded in faint star streams revealed in the deep exposure, contrasting with spiky foreground Milky Way stars.

The entry was produced by Jerry Bonnell, Cecilia Chirenti, Robert Nemiroff, and Keighley Rockcliffe for NASA and Michigan Technological University.