Heart of our Milky Way revealed in new radio image

This brief video gives you a look at the new image of the Milky Way center taken in radio wavelengths. It’s the largest image the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has ever taken. Video via ALMA (ESO/ NAOJ/ NRAO)/ S. Longmore et al. Background: ESO/ D. Minniti et al.

• At the heart of the Milky Way lies an enormous cloud feature that astronomers have now imaged in great detail using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.
• The image reveals complex gas clouds spanning 650 light-years, with chemical molecules and massive star formation, orbiting the galaxy’s supermassive black hole.
• These data will help scientists study extreme star formation and better understand how galaxies evolved in the early universe.

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Complex gas structures at the Milky Way center

The space between stars is not empty. Instead, it is permeated with several forms of gas, mostly containing hydrogen. Some of these gases exist as dense regions of cold molecular clouds. On February 25, 2026, astronomers said they had imaged, in unprecedented detail, an enormous swath of clouds at the center of our Milky Way. Specifically, they captured this large image in millimeter radio wavelengths. It revealed new details of a chaotic gaseous region with massive stars that orbits the supermassive black hole in our galaxy’s center.

Astronomers call this cloud, 28,000 light-years away, the Central Molecular Zone (CMZ). It spans 650 light-years across, and if you projected it on our sky, it would be the width of three full moons.

The scientists observed it using the Atacama Large Millimeter/submillimeter Array, better known as ALMA. That’s an observatory with 66 radio telescopes located in the Atacama Desert of northern Chile.

Over 60 scientists around the world collaborated to create this treasure trove of data. They named this project ACES, short for the ALMA CMZ Exploration Survey.

The team announced their project on February 25, 2026. It will soon be published as a series of papers in the journal Monthly Notices of the Royal Astronomical Society.

The Central Molecular Zone in unprecedented detail

The clouds in the Central Molecular Zone (CMZ) are invisible to our eyes. But they shine faintly in radio wavelengths that can be detected by sensitive radio telescopes.

ALMA scanned the Central Molecular Zone, taking multiple sub-images of the 650-light-year-wide region. Then, researchers joined each sub-image together to create an enormous mosaic. In fact, it’s the largest image that the observatory has ever created.

This big, high-resolution image has uncovered details scientists have never seen before. For instance, astronomers saw a complex network of filaments, with structures that ranged in size from dozens of light-years across to gases surrounding individual stars. In addition, images in different radio wavelengths revealed the chemical makeup of the clouds, from simple molecules like silicon monoxide to complex organic molecules such as methanol, acetone and ethanol.

Katharina Immer, a project participant at the European Southern Observatory, said:

We anticipated a high level of detail when designing the survey, but we were genuinely surprised by the complexity and richness revealed in the final mosaic.

Star formation in extreme environments

This region is intriguing to astronomers because it is such an extreme environment, not unlike conditions in the early universe.

Steve Longmore, project member at the Liverpool John Moores University in the UK, said:

The Central Molecular Zone hosts some of the most massive stars known in our galaxy, many of which live fast and die young, ending their lives in powerful supernova explosions, and even hypernovas.

By studying how stars are born in the Central Molecular Zone, we can also gain a clearer picture of how galaxies grew and evolved. We believe the region shares many features with galaxies in the early universe, where stars were forming in chaotic, extreme environments.

Steve Longmore talks about the new image of the Central Molecular Zone obtained using ALMA. Video via S. Longmore.

Chemistry of molecular clouds at the Milky Way center

In cold molecular clouds, a molecule can spin at certain speeds, depending on its chemical makeup. However, when the speed changes from one to another, it emits or absorbs a specific radio wavelength of electromagnetic radiation. Plus, the value of that specific wavelength depends on the chemical composition of the molecule. As a result, by looking at the radio spectrum, astronomers can identify the chemical composition of the cloud. (This video from the National Radio Astronomy Observatory illustrates this mechanism in more detail.)

Immer has a special interest in astrochemistry. She said the molecular clouds near the center of our galaxy are more turbulent and warmer compared to those farther out. Therefore, she wondered, do stars and chemicals form differently in the Central Molecular Zone compared to outer parts of the Milky Way?

Katharina Immer talks about the new ALMA image of the Central Molecular Zone. Video via European Southern Observatory.

Future studies of the Central Molecular Zone

The data collected so far will keep astronomers busy for years. But they’re not stopping there.

Ashley Barnes, at the European Southern Observatory, said:

The upcoming ALMA wideband sensitivity upgrade, along with ESO’s Extremely Large Telescope, will soon allow us to push even deeper into this region — resolving finer structures, tracing more complex chemistry and exploring the interplay between stars, gas and black holes with unprecedented clarity. In many ways, this is just the beginning.

Bottom line: Astronomers used powerful radio telescopes to build an unprecedentedly detailed view of cold molecular gases in the center of the Milky Way.

Source: A collection of preprints listed at the ALMA Central Molecular Zone Exploration Survey website.

Via European Southern Observatory

Read more: Milky Way center: Threads of hot gas and magnetic fields

The post Heart of our Milky Way revealed in new radio image first appeared on EarthSky.