The Andromeda galaxy is the galaxy next door, a very faint, fuzzy thing in the night sky, larger than a full moon. Textbooks claim it’s visible to the naked eye. Most of us have never noticed it. Too ...

Cepheid stars have predictable brightness changes linked to their periods. This period-brightness relationship lets astronomers calculate a Cepheid's distance. Hubble found a Cepheid in the Andromeda ...

Hubble had been in space for less than two years when its Goddard High Resolution Spectrograph detected traces of boron in a not-too-distant star. At an estimated age of 14.5 billion years, the star ...

Historically, the Andromeda Galaxy (M31) was a subject of extensive debate, initially considered a "nebulous smear" and later central to the "island universe" hypothesis proposing its status as an ...

Warning: This graphic requires JavaScript. Please enable JavaScript for the best experience. The Andromeda galaxy is the galaxy next door, a very faint, fuzzy thing ...