The discovery marks the first time ethyl alcohol, the same type in alcoholic beverages, has been observed in a comet, researchers said.
The finding adds to the evidence that comets could have been a source of the complex organic molecules necessary for the emergence of life, they said.
"We found that comet Lovejoy was releasing as much alcohol as in at least 500 bottles of wine every second during its peak activity," said Nicolas Biver of the Paris Observatory, France, lead author of a research paper published in journal Science Advances.
Comets are frozen remnants from the formation of our solar system. Scientists are interested in them because they are relatively pristine and therefore hold clues to how the solar system was made.
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Most orbit in frigid zones far from the Sun. However, occasionally, a gravitational disturbance sends a comet closer to the Sun, where it heats up and releases gases, allowing scientists to determine its composition.
Comet Lovejoy (formally catalogued as C/2014 Q2) was one of the brightest and most active comets since comet Hale-Bopp in 1997.
They observed a microwave glow from the comet using the 30-meter diameter radio telescope at Pico Veleta in the Sierra Nevada Mountains of Spain.
The advanced equipment was capable of analysing a wide range of frequencies simultaneously, allowing the team to determine the types and amounts of many different molecules in the comet despite a short observation period.
Discovery of complex organic molecules in Lovejoy and other comets gives support to this hypothesis.
"The result definitely promotes the idea the comets carry very complex chemistry," said Stefanie Milam of NASA's Goddard Space Flight Centre in Greenbelt, Maryland, a co-author on the paper.