Andromeda Galaxy (M31)

Nearest major galaxy to the Milky Way, on a collision course with our galaxy in roughly 4.5 billion years.

Core Principles & Analysis

• In 1923 Edwin Hubble found a Cepheid variable star in Andromeda, proving it lies far beyond the Milky Way.
• It is approaching the Milky Way at about 110 km/s, measured from the blueshift of its light.
• At 2.5 million light-years, it is the most distant object easily visible to the naked eye.

Specifications & Metrics

• GALAXY TYPE: Spiral (SA(s)b)
• DISTANCE: 2.5 million light-years
• DIAMETER: ~220,000 light-years