Largest ALMA image ever shows the molecular gas in the centre of the Milky Way

Eso_eso2603a_1024

eso_eso2603a February 25th, 2026

Credit: ALMA(ESO/NAOJ/NRAO)/S. Longmore et al. Background: ESO/D. Minniti et al.

This image shows the complex distribution of molecular gas in the Central Molecular Zone (CMZ) of the Milky Way. It was obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. This map is as long as three full Moons side-by-side in the sky, and it is in fact the largest ALMA image ever obtained. This map is part of ACES — the ALMA CMZ Exploration Survey — a project designed to understand how gas condenses into stars in the extreme and chaotic environment at the heart of our galaxy. The survey has charted the distribution of dozens of different molecules, five of which are shown here in different colours: sulphur monoxide (cyan), silicon monoxide (green), isocyanic acid (red), cyanoacetylene (blue), and carbon monosulphide (magenta). The stars in the foreground of this image were observed at infrared wavelengths (Y, Z and J filters) with ESO’s VISTA telescope as part of a different project. The actual density of stars in the CMZ is much higher than what is shown here, where we have opted to highlight the details in the molecular cloud. Note that the edges of the ALMA map appear somewhat sharp because the ALMA observations do not cover the entire rectangular area here.

Provider: European Southern Observatory

Image Source: https://www.eso.org/public/images/eso2603a/

Curator: European Southern Observatory, Garching bei München, None, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details Image Details

Image Type
Observation
Object Name
Central Molecular Zone
Subject - Milky Way
Galaxy > Component > Center/Core
Eso_eso2603a_128
 

Position Details Position Details

Position (ICRS)
RA = 17h 46m 3.5s
DEC = -28° 50’ 2.8”
Orientation
North is 58.7° CCW
Field of View
1.5 x 0.6 degrees
Constellation
Sagittarius

Color Mapping Details Color Mapping

  Telescope Spectral Band Wavelength
Cyan ALMA (Band 3) Millimeter (SO) 3.0 mm
Green ALMA (Band 3) Millimeter (SiO) 3.5 mm
Red ALMA (Band 3) Millimeter (HNCO) 3.4 mm
Blue ALMA (Band 3) Millimeter (HC3N) 3.0 mm
Magenta ALMA (Band 3) Millimeter (CS) 3.1 mm
Spectrum_ir1
Cyan
Green
Red
Blue
Magenta
Eso_eso2603a_1280
×
ID
eso2603a
Subject Category
B.5.4.9  
Subject Name
Central Molecular Zone
Credits
ALMA(ESO/NAOJ/NRAO)/S. Longmore et al. Background: ESO/D. Minniti et al.
Release Date
2026-02-25T14:00:00
Lightyears
Redshift
Reference Url
https://www.eso.org/public/images/eso2603a/
Type
Observation
Image Quality
Distance Notes
Facility
Atacama Large Millimeter/submillimeter Array, Atacama Large Millimeter/submillimeter Array, Atacama Large Millimeter/submillimeter Array, Atacama Large Millimeter/submillimeter Array, Atacama Large Millimeter/submillimeter Array
Instrument
Band 3, Band 3, Band 3, Band 3, Band 3
Color Assignment
Cyan, Green, Red, Blue, Magenta
Band
Millimeter, Millimeter, Millimeter, Millimeter, Millimeter
Bandpass
SO, SiO, HNCO, HC3N, CS
Central Wavelength
3019000, 3452000, 3410000, 2996000, 3060000
Start Time
Integration Time
Dataset ID
None, None, None, None, None
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
266.5145396, -28.8341246
Reference Dimension
11119.0, 4080.0
Reference Pixel
5560.5, 2040.5
Scale
-0.0001388888, 0.0001388888
Rotation
58.65
Coordinate System Projection:
TAN
Quality
Full
FITS Header
Notes
Creator (Curator)
European Southern Observatory
URL
https://www.eso.org
Name
Email
Telephone
Address
Karl-Schwarzschild-Strasse 2
City
Garching bei München
State/Province
None
Postal Code
D-85748
Country
Germany
Rights
Creative Commons Attribution 4.0 International License
Publisher
European Southern Observatory
Publisher ID
eso
Resource ID
eso2603a
Metadata Date
2025-09-02T12:07:33+02:00
Metadata Version
1.1
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Detailed color mapping information coming soon...

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There is no distance meta data in this image.

 

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