Hello, neighbor! See the Andromeda galaxy like never before in stunning new image from NASA’s Chandra telescope (video)

The galaxy next door to the Milky Way, Andromeda, has never looked as stunning as it does in a new image from NASA’s Chandra X-ray space telescope.

The image of the galaxy, also known as Messier 31 (M31), was created with assistance from a range of other space telescopes and ground-based instruments including the European Space Agency (ESA) XMM-Newton mission, NASA’s retired space telescopes GALEX and the Spitzer Space Telescope as well as the Infrared Astronomy Satellite, COBE, Planck, and Herschel, in addition to radio data from the Westerbork Synthesis Radio Telescope.

All these instruments observed Andromeda in different wavelengths of light across the electromagnetic spectrum, with astronomers bringing this data together to create a stunning and intricate image. The image is a fitting tribute to astronomer Vera C. Rubin, who was responsible for the discovery of dark matter thanks to her observations of Andromeda.

As the closest large galaxy to the Milky Way, at just around 2.5 million light-years away, Andromeda has been vital in allowing astronomers to study aspects of galaxies that aren’t accessible from our own galaxy. For example, from inside the Milky Way, we can’t see our galaxy’s spiral arms, but we can see the spiral arms of Andromeda.

Every wavelength of light that was brought together to create this incredible new image of Andromeda tells astronomers something different and unique about the galaxy next door.

For example, the X-ray data provided by Chandra has revealed the high-energy radiation released from around Andromeda’s central supermassive black hole, known as M31*.

M31* is considerably larger than the supermassive black hole at the heart of the Milky Way, known as Sagittarius A* (Sgr A*). While our home supermassive black hole has a mass 4.3 million times that of the sun, M31* dwarfs it with a mass 100 million times that of the sun. M31* is also notable for its occasional flares, one of which was observed in X-rays back in 2013, while Sgr A* is a much “quieter” black hole.

What connects Andromeda and Rubin?

Andromeda was chosen as a tribute to Rubin because this neighboring galaxy played a crucial role in the astronomer’s discovery of a missing element of the universe. An element that we now call dark matter.

In the 1960s, Rubin and collaborators precisely measured the rotation of Andromeda. They found that the speed at which this galaxy’s spiral arms spun indicated that the galaxy was surrounded by a vast halo of an unknown and invisible form of matter.

The mass of this matter provided the gravitational influence that was preventing Andromeda from flying apart due to its rotational speed. The gravity of its visible matter wouldn’t have been sufficient to hold this galaxy together.

Since then, astronomers have discovered that all large galaxies seem to be surrounded by similar haloes of what is now known as dark matter. This has led to the discovery that the matter which comprises all the things we see around us  —  stars, planets, moons, our bodies, next door’s cat  —  accounts for just 15% of the “stuff” in the cosmos, with dark matter accounting for the other 85%. The finding has also prompted the search for particles beyond the standard model of particle physics that could compose dark matter.

Thus, there’s no doubt that Rubin’s work delivered a watershed moment in astronomy, and one of the most important breakthroughs in modern science, fundamentally changing our concept of the universe.

June 2025 has been a brilliant month of recognition of Rubin’s immense impact on astronomy and her lasting legacy. In addition to this tribute image, the Vera C. Rubin Observatory released its first images of the cosmos as it gears up to conduct a 10-year observing program of the southern sky called the Legacy Survey of Space and Time (LSST).

Additionally, in recognition of Rubin’s monumental contributions to our understanding of the universe, the United States Mint recently released a quarter featuring Rubin as part of its American Women Quarters Program. She is the first astronomer to be honored in the series.