Inbound interstellar comet Borisov has a toxic tail

The space rock isn't from around here, but the poisons it carries are.

Eric Mack Contributing Editor
Eric Mack has been a CNET contributor since 2011. Eric and his family live 100% energy and water independent on his off-grid compound in the New Mexico desert. Eric uses his passion for writing about energy, renewables, science and climate to bring educational content to life on topics around the solar panel and deregulated energy industries. Eric helps consumers by demystifying solar, battery, renewable energy, energy choice concepts, and also reviews solar installers. Previously, Eric covered space, science, climate change and all things futuristic. His encrypted email for tips is ericcmack@protonmail.com.
Expertise Solar, solar storage, space, science, climate change, deregulated energy, DIY solar panels, DIY off-grid life projects, and CNET's "Living off the Grid" series Credentials
  • Finalist for the Nesta Tipping Point prize and a degree in broadcast journalism from the University of Missouri-Columbia.
Eric Mack
2 min read

The first interstellar comet: c/2019 Q4

Gemini Observatory/NSF/AURA

The first comet seen visiting our solar system from another star system isn't coming bearing gifts. What comet 2I/Borisov is bringing our way, though, is toxic gas that can be produced from cyanide compounds.

Astronomers reported in a recent issue of the Astrophysical Journal Letters that they'd detected CN gas, which is a molecule of one carbon atom and one nitrogen atom linked together, in the comet's atmosphere.

The discovery doesn't mean intergalactic aliens have launched a cometary canister of tear gas across the cosmos. Rather, it shows that comets from beyond the solar system could be quite similar to the local ones we see all the time, which also bring CN gas with them. 

"We could have expected to observe a very different composition, since we don't know the origin and history of this object, which probably wandered for millions of years between the stars before reaching us," the University of Liege's Emmanuël Jehin explained in a statement. "This would indicate that the physical and chemical processes of formation of these small bodies, which are the building blocks of planets and perhaps the source of water and organic material on Earth, would be very common in the galaxy."

The pungent, poisonous gas has been spotted trailing other comets. When Earth was set to drift through the tail of Halley's comet over a century ago, The New York Times quoted a French astronomer saying the comet's tail could "possibly snuff out all life on the planet."

That obviously didn't happen then, as Earth's atmosphere is significant and able to easily disperse the toxic tail of one space rock. 

There's far less to worry about this time around because comet Borisov won't be coming particularly close to Earth and will stay beyond the orbit of Mars as it passes through the solar system.  

So it's definitely OK to breathe easy as it comes closer over the next several weeks.