Highly Alcoholic Comet Offers Clues to How the Solar System Formed Billions of Years Ago

Scientists have discovered that a comet released an abnormally large amount of alcohol into space as it passed by Earth in December 2018.

When Comet 46P/Wirtanen shot by our planet two-and-a-half years ago, scientists had just completed a major upgrade to a telescope at the Keck Observatory on Maunakea in Hawaii.

This allowed them to gather data on the comet using a process called spectroscopy, which can reveal important properties of any body which emits or absorbs light.

The data revealed that 46P/Wirtanen "has one of the highest alcohol-to-aldehyde ratios measured in any comet to date," Neil Dello Russo, co-author of a study into the comet's composition and a cometary scientist at Johns Hopkins University, told the Keck Observatory.

This alcohol is not something you'd want to drink, though. The study, titled "First Comet Observations with NIRSPEC-2 at Keck," and published in the Planetary Science Journal, identifies the alcohol present in the comet as methanol, or CH3OH.

This is not the same as the alcohol found in alcoholic beverages, which is ethanol, or C2H5OH. Methanol can cause blindness and death, even in relatively small doses.

Still, Dello Russo said the methanol present in the comet tells researchers about how carbon, oxygen, and hydrogen molecules were distributed in the early solar system.

The study states that the methanol/formaldehyde abundance ratio in 46P/Wirtanen is "closer to the highest measured values in comets."

46P/Wirtanen
A NASA photo shows the comet 46P/Wirtanen, which made its closest approach to Earth on December 16, 2018. NASA

The observations are important because they will help scientists decide whether or not to send a spacecraft to 46P/Wirtanen to get even more insight.

In a statement, the Keck Observatory described comets as relics of the cosmic past, because they contain the original minerals the solar system was made from.

Greg Doppmann, a staff astronomer at the observatory, said: "Comet studies like this are exciting because they serve as a launchpad for answering the million dollar question—are we alone?

"The organic compounds on comets tell us what ingredients formed our solar system and served as precursors to life."

The alcohol is not all the scientists found. Normally, when comets travel closer to the sun, particles in their centers heat up, turn to gas, and produce a coma—a cloak of gas and dust that surrounds and trails behind the comet as it travels through space.

But with 46P/Wirtanen, researchers discovered that the temperature measured for water gas in the comet's tail did not decrease significantly as it traveled away from the comet's core.

This suggests that something is heating up the water gas—but scientists are not too sure what.

One possible explanation is that sunlight could be ionizing some of the atoms in the coma, releasing super-charged electrons that transfer heat to the coma's water gas.

Another is that solid chunks of ice may by flying off the comet, which heat and turn to gas away from the core.

Comet
A stock photo shows a comet flying through space. Comets often leave trails because their material is heated up by the sun. solarseven/Getty