The Andromeda Galaxy is a spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31 ...

The two keys to Edwin Hubble 's breakthrough discovery were forged by others in the 1910s. The first key, the period-luminosity scale discovered by Henrietta Leavitt, allowed astronomers to calculate ...

The Andromeda Galaxy is the closest large spiral galaxy to our own Milky Way galaxy. Excluding the Large and Small Magellanic Clouds — both visible from Earth’s Southern Hemisphere — the Andromeda ...

Cepheids are rare variable stars with periods ranging from about 1 to 120 days. Their light curve — a chart showing brightness over time — is characterized by rapid brightening followed by slow ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. M31, the spiral galaxy in Andromeda, with its two companion ...

Andromeda is the nearest major galaxy to the Milky Way, yet every view of it is ancient. The light reaching Earth tonight began crossing intergalactic space about 2.5 million years ago. That journey ...

The famed Andromeda Galaxy, or M31, draws attention at public star parties not only because it is the nearest major member of the Local Group to our Milky Way, but also because most people are aware ...

"Beyond the Milky Way lie billions of other galaxies, drifting a few million light years from one another like lily pads floating on the surface of a pond." — Timothy Ferris in Seeing in the Dark A ...

In the years following the launch of NASA's Hubble Space Telescope, astronomers have tallied over 1 trillion galaxies in the universe. But only one galaxy stands out as the most important nearby ...