Ingredients for life on Earth may have been delivered by comets, study says

Scientists know that the ingredients necessary to form life appeared on Earth early in its history, but they're still trying to figure out exactly how that happened. A new study suggests that comets were the cosmic messengers depositing crucial elements like phosphorus on Earth billions of years ago.

"Life appeared on Earth about 4 billion years ago, but we still do not know the processes that made it possible," said Víctor Rivilla, lead study author and researcher at the Arcetri Astrophysical Observatory, part of Italy's National Institute for Astrophysics, CNN reports.

In order to determine how phosphorus arrived on Earth, scientists needed to retrace its journey back through space. Two tools enabled the search: the Atacama Large Millimeter/submillimeter Array of telescopes in Chile and the European Space Agency's Rosetta spacecraft.

The telescope array, known as ALMA, was able to peer into a region of star formation called AFGL 5142. In this region, stars are born from massive clouds of gas and dust -- and it's here that some of the key building blocks of the solar system, as well as life, can be found. Using the telescope array, astronomers spotted the origin of molecules like phosphorus monoxide.

The molecules containing phosphorus are made in the wake of massive stars as they form. Young stars release gas flows that carve pathways through clouds in interstellar space. Phosphorus builds up on the walls of these pathways as the stars release radiation, and phosphorus monoxide is created in abundance.