Life’s building blocks found in ‘primitive’ galaxy Read time: 3 minutes The basic building blocks for life may already have been around when the universe was still young. Living things consist of organic molecules. Organic molecules consist of various atoms, like hydrogen, carbon, oxygen and nitrogen. From these atoms, you can build all kinds of organic molecules: simple ones with just a few atoms, or very complex ones with dozens of atoms. But without large numbers of the right atoms (especially carbon, oxygen and nitrogen) it is very hard to build organic molecules. That’s why astronomers believed that complex organic molecules couldn’t form in the very first galaxies. Back then, when the universe was still young, it consisted almost solely of hydrogen and helium. Hydrogen and helium are the two simplest atoms in nature. Large amounts of heavier atoms like carbon, oxygen and nitrogen, were only produced at a later stage, in the interiors of stars. But ALMA has now detected complex organic molecules in a small galaxy close to our Milky Way. The galaxy is known as the Large Magellanic Cloud. Just like the very first galaxies in the universe, it has a very ‘primitive’ chemical makeup, with only small amounts of heavy atoms. So, it was a surprise to find complex organic molecules in the Large Magellanic Cloud – molecules with funny names like methanol, dimethyl ether and methyl formate. Apparently, complex organic molecules can also form when only small amounts of heavy atoms are available. If that is true for the Large Magellanic Cloud, it was probably also true for the very first galaxies in the universe, which also had a ‘primitive’ chemical makeup. Complex organic molecules are the basic building blocks of life, so the discovery indicates that life may have formed earlier than most astronomers would expect. What? The Large Magellanic Cloud is one of two ‘satellite galaxies’ of our own Milky Way Galaxy. (The other one is the Small Magellanic Cloud.) The Large Magellanic Cloud is some 170,000 light-years away. On a clear night, it is easily visible from the southern hemisphere, as a nebulous patch of light. The satellite galaxy contains many star-forming regions: hot clouds of gas and dust where new stars are born. In one of those stellar nurseries, known as N113, ALMA detected the faint millimeter radiation from complex organic molecules. Who? The discovery of complex organic molecules in the Large Magellanic Cloud was made by a large international team of astronomers from the United States, Japan, the United Kingdom and Germany. The team was led by Marta Sewilo of NASA’s Goddard Space Flight Center. Marta and her colleagues published their discovery in The Astrophysical Journal Letters, a professional magazine of astronomy. ALMA URL