Atacama Large Millimeter/submillimeter Array (ALMA)

The Atacama Large Millimeter/submillimeter Array (ALMA) is a radio observatory of 66 high-precision antennas on the Chajnantor Plateau, 5,000 meters up in Chile’s Atacama Desert. It observes at millimeter and submillimeter wavelengths, where cold gas and dust glow: the raw material of stars and planets. ALMA is a partnership of ESO, the US National Science Foundation and Japan’s NINS, with Canada, Taiwan, South Korea and Chile. It began science observations in 2011 and has been fully operational since March 2013, at a cost of about US$1.4 billion.

Flagship instruments

• 66 antennas that work together as one interferometer, with a support facility at 2,900 meters.
• Wideband Sensitivity Upgrade (WSU): will first double, and eventually quadruple, the system bandwidth. Doubling alone makes continuum imaging about three times faster.

Recent results

ALMA’s 2014 image of the HL Tauri disk, with its concentric rings and gaps, became the emblem of planet formation in action. In 2026 that picture got a direct test: Elias 2-24 b, the youngest exoplanet yet found, sits in a gap of its star’s disk and was confirmed with ALMA alongside Keck and the VLT. ALMA also showed that the “Shadow Blaster” galaxy, the likely source of an IceCube neutrino, lies behind a strong gravitational lens. In July 2026 the observatory passed 5,000 refereed scientific publications.

What to watch, 2026-2030

• October 2026: the Cycle 13 observing season begins.
• By 2030: the first elements of the Wideband Sensitivity Upgrade, expected “later this decade”.

Why scientists are converging here

ALMA turned planet formation from theory into images, and the newest results link disk gaps directly to growing planets. With faster imaging coming from the upgrade, it remains the main tool for watching stars and planets assemble, and a natural partner to infrared telescopes such as the Keck Observatory and the VLT.