The strange chemical upon Venus can come from volcanoes, not from life.

A mysterious breath of an unstable chemical in the sky of Venus may not be a sign of life, but the result of exploding volcanic eruptions, according to a new study.

Last year, scientists detected evidence of the phosphine molecule in the clouds of the sun's second rock. The chemical, which is made up of one atom of phosphorus and three atoms of hydrogen, should break down quickly in atmospheres that are rich in oxygen, such as those of Earth and Venus.

On Earth, phosphine is manufactured in plants and is close to certain types of microbes. As such, the researchers suggested phosphine on Venus might be a suspicion of life in this infernal world in a hotly debated assumption. One opposition camp asked whether or not phosphine has been definitively seen, while another debate whether life is the only possible cause of phosphine on Venus.

Now, a pair of planetary scientists suggest that explosive volcanic eruptions may also throw up phosphine in the Venusian atmosphere. "It is possible that we are witnessing an active volcanism on Venus," Space.com.

To see if there might be a nonbiological explanation for phosphine in the skies of Venus, the researchers analyzed lab data on phosphorus chemistry as well as calculations of volcanic and atmospheric activity.

Scientists have discovered that volcanism on Venus could potentially bring small quantities of phosphorus-laden compounds, called phosphates, to the surface of the planet's mantle. Explosive volcanic eruptions could then discharge these phosphates—as volcanic dust—into the atmosphere, where the chemical could react with sulfuric acid to form phosphine.

For phosphides to reach the altitudes necessary for the previously reported phosphine detection, the researchers suggested a Venusian outburst on a scale comparable to the Krakatau eruption on Earth in 1883 was necessary. That catastrophe was one of the deadliest and most destructive volcanic events in recorded history on Earth, destroying more than 70% of the Indonesian island of Krakatoa and its surrounding archipelago.

"The question of whether Venus is active at the volcanic level has been discussed," Truong said. "If phosphine actually exists, our research suggests that active volcanism could be a plausible means of producing phosphine on Venus."

The scientists noted that previous research, such as spikes in sulfur dioxide levels at the cloud tops of Venus and fluctuations in the amount of haze seen above these clouds, has suggested Venus might indeed possess enough ongoing volcanism to generate detectable phosphine.

"Venus looks like a volcanic planet — it has a very youthful surface, and there is evidence it has experienced substantial resurfacing recently in its history," study senior author Jonathan Lunine, a planetary scientist at Cornell University, told Space.com.

Future research will rely on the Atacama Large Millimeter/submillimeter Array (ALMA) radio network in Chile and other observatories to confirm whether Venus actually has phosphate, Truong said. In addition, "there are now three very exciting planetary missions to Venus," remarked Mr. Lunine—DAVINCI+ and VERITAS from NASA and EnVision from the European Space Agency. "I would like to look at how active volcanism and phosphine can be detected in any of these missions."

Truong and Lunine wrote about their discoveries in the journal Proceedings of the National Academy of Sciences.