On the Road Back from ALMA: A Glimpse into the Universe’s Secrets
- Abbas Mokhtarzadeh
- Aug 6
- 3 min read
On the Road Back from ALMA: A Glimpse into the Universe’s Secrets
December 2022
As we journeyed back from our ACEAP expedition, one stop continued to echo in our minds: the ALMA Observatory; a stunning array of radio telescopes perched high on Chile’s Chajnantor Plateau. This site, among the highest and driest on Earth, offers ideal conditions to observe the cold and distant universe, capturing invisible signals that reveal the origins of stars, galaxies, and perhaps life itself.
APEX: A Path to the Stars
Nearby stands APEX (Atacama Pathfinder Experiment), a 12-meter single-dish submillimeter telescope located at over 5,100 meters elevation. Built using a prototype ALMA antenna, APEX observes similar wavelengths and helped pave the way for ALMA’s full array. Despite its solitary design, APEX is a scientific powerhouse in its own right, contributing to discoveries about molecular clouds, star birth, and galactic evolution.
Learn more: https://www.eso.org/public/teles-instr/apex/
The Atacama: A Natural Window into the Cosmos
The Atacama Desert, stretching across northern Chile, is Earth’s ultimate natural observatory. With its extreme dryness, high altitude, and minimal light pollution, it allows telescopes like ALMA and APEX to detect the faintest cosmic whispers—signals that are lost to moisture and interference elsewhere. These rare conditions have made the region a cornerstone of 21st-century astronomy.
ALMA at a Glance
ALMA (Atacama Large Millimeter/submillimeter Array) is the world’s most powerful radio telescope, built through a global collaboration among Europe, North America, East Asia, and Chile. Operating at millimeter and submillimeter wavelengths, ALMA captures a rare “rain” of invisible cosmic light, unlocking the mysteries of the cold universe: from star and planet formation to the earliest galaxies.
With 66 high-precision antennas spread across distances of up to 16 kilometers, ALMA functions as a single, massive telescope—offering resolution sharper than even the Hubble Space Telescope.
Learn more: https://www.almaobservatory.org/en/home/
Impact Beyond Astronomy
The discoveries made at ALMA and APEX go far beyond astronomy. Their advanced technologies contribute to breakthroughs in medical imaging, climate science, and telecommunications. These observatories also fuel international cooperation and scientific education, inspiring new generations of researchers and explorers.
A Familiar Design
The ALMA dishes—like the one pictured here—share much in common with APEX:
12-meter parabolic reflector
High surface accuracy for submillimeter precision
Alt-azimuth mount with a Cassegrain focus
APEX and ALMA stand as siblings in the high desert, each extending humanity’s vision into the invisible universe.
Cerro Chajnantor: The Shining Sentinel
Looming beside the ALMA site is Cerro Chajnantor, a prominent peak rising to 5,640 meters (18,500 feet). Its name is derived from Aymara, an Indigenous Andean language: chajña meaning “to appear,” “to shine,” or “to dawn.” Thus, Chajnantor may be interpreted as “the shining place” or “place of appearance.” The mountain’s prominence and visibility likely earned it this name: fitting for a site that captures the light of the cosmos.
On our return, we were treated to another rare sight—a remolino de polvo, a swirling dust devil twisting gracefully across the desert floor, seeing in left side of radio telescope! Not a tornado, but a captivating desert phenomenon, born from the intense sun and thin air, reminding us that even in the driest place on Earth, the atmosphere is alive with motion.
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