Chile’s ALMA confirms that comets forge organic molecules in their atmospheres’

An international team of scientists working on  the Atacama Large Millimeter/sub-millimeter Array (ALMA) have released 3d composite images detailing how organic molecules are created inside the atmosphere or the comets ISON and Lemmon. 

 The 3-D images created by  the ALMA observations were produced  by combining high-resolution 2-D images of the comets with high-resolution spectra obtained from three important organic molecules — hydrogen cyanide (HCN), hydrogen isocyanide (HNC), and formaldehyde (H2CO). These spectra were taken at every point in each image. They identified not only the molecules present, but also their velocities, which provided the third dimension, indicating the depths of the cometary atmospheres.

Understanding organic dust is important because such materials are more resistant to destruction during atmospheric entry, and some could have been delivered intact to the early Earth, thereby fueling the emergence of life,” said Michael Mumma from the Goddard Center for Astrobiology. “These observations open a new window on this poorly known component of cometary organics.”

“So, not only does ALMA let us identify individual molecules in the coma, it also gives us the ability to map their locations with great sensitivity,” said Anthony Remijan from the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia.

Comet ISON (formally known as C/2012 S1) was observed with ALMA on November 15-17, 2013, when it was only 75 million kilometers from the Sun (about half the distance of the Earth to the Sun). Comet Lemmon (formally known as C/2012 F6) was observed on June 1-2, 2013, when it was 224 million kilometers from the Sun (about 1.5 times the distance of the Earth to the Sun). 


The Atacama Large Millimeter/sub-millimeter Array (ALMA) is an astronomical interferometer of radio telescopes in the Atacama desert of northern Chile.  To minimize atmospheric interference the array has been constructed on the Chajnantor plateau at an altitude of 16,500 ft. ALMA  consists of 66 12-metre (39 ft), and 7-metre (23 ft) diameter radio telescopes which work together to combine there collective power.  ALMA is an international partnership between Europe, the United States, Canada, East Asia and the Republic of Chile. At $ 1.4 billion ALMA  is the most expensive ground-based telescope in operation in the world.


This rotating 3-D ALMA map shows how HCN molecules are released from the nucleus of comet Lemmon and then spread evenly throughout the atmosphere.

If you are interested in learning more about ALMA check out Tony Beasley’s  TED Talk

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