The Atacama Desert has a stark and beautiful landscape that mirrors the mysterious celestial objects that the ALMA observatory is investigating. This Chilean region is a quiet, peaceful place where flamingos swarm in salt fields while the sun rises over volcanoes in the distance. It’s no wonder that the area is called the Valley of the Moon. It doesn’t just appear to be a unique location — scientific evidence shows that the soil is so dry that it is comparable to Martian land. Here, in the world’s driest desert, on the Chajnantor plateau, the ALMA observatory scans the sky to learn about the universe.
A Prime Location for Observing the Sky
ALMA stands for Atacama Large Millimeter/submillimeter Array, but the acronym also spells “alma,” the Spanish word for soul. An international consortium of countries built the observatory, which includes 66 antennae that make up 6,492 square meters of total surface area of radio wave data collection, according to ALMA’s website. Several geological factors make Atacama the perfect place to observe the universe:
- Lack of humidity. With no clouds or moisture to get in the way, Atacama has some of the world’s clearest skies, according to Space.com.
- High altitude. At an altitude of 16,570 feet above sea level, ALMA is one of the highest instruments on Earth. It’s located so high that there is minimal light distortion from the atmosphere.
- Minimal light pollution and interference. The region is not overly developed, which helps astronomers observe space without any interference from other electronics or infrastructure such as city lights.
The desert skies are so clear and the antennas are so powerful that the images obtained at ALMA are 10 times more detailed than the Hubble Space Telescope images, according to the ALMA website. The atmospheric conditions are ideal for transparency and stability at millimeter and submillimeter wavelengths. Space.com says ALMA is the world’s most powerful observatory for studying the universe at these wavelengths.
ALMA’s capabilities are world-renowned, but it’s not a place where tourists can go peer through a telescope to see the stars. The instruments at ALMA observe long waves of invisible light, a portion of electromagnetic spectrum that reveals the dark universe. Interestingly, the region’s indigenous people were observing dark space long before the observatory was built. According to ALMA’s website, while some cultures looked at the stars that formed constellations, Andean cultures looked at the dark shapes between constellations, just like the dark universe that ALMA is currently investigating with the most powerful telescopes.
Between the Stars
The cold universe isn’t picked up by optic telescopes, but ALMA’s telescopes are designed for the specific purpose of viewing that mysterious portion of the universe. This helps scientists observe ancient, distant planets and stars that could help us understand how these celestial objects are formed. The location also has the perspective of the southern sky, which includes the center of the Magellanic Clouds and the center of the Milky Way. ALMA’s high resolution enables scientists to find clues about the universe, such as a 2018 report in Astronomy & Astrophysics. Scientists detected cloudlets surrounding Sagittarius A*, the supermassive black hole at the center of the Milky Way.
It’s usually difficult for scientists to observe these longer waves in the electromagnetic spectrum because water vapor in Earth’s atmosphere absorbs these waves, but that’s not an issue in ALMA’s dry, high location. According to the New York Times, 70 percent of the world’s professional astronomy observatories are located in Chile, mostly in Atacama. ALMA has an array of the most powerful telescopes in the best possible location.
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