Messier 91 (M91)

The faintest barred spiral of the Virgo set, once lost because Messier misplotted it.

Core Principles & Analysis

• Its position error kept astronomers hunting for it until William Herschel's son matched it in 1783.
• It lies at the opposite end of the Markarian Chain from M84.
• A supernova was recorded in it in 2020.

Specifications & Metrics

• GALAXY TYPE: Barred spiral (SBb)
• DISTANCE: ~63 million light-years