A mysterious whiff of an unstable chemical in the skies of Venus may not be a sign of life but the result of explosive volcanic eruptions, a new study finds.

Last year, scientists reported detecting signs of the molecule phosphine in the clouds of the second rock from the sun. 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 made in factories and is found near certain kinds of microbes. As such, researchers suggested phosphine on Venus might be a hint of life on that hellish world in a hotly debated hypothesis. One opposition camp has questioned whether or not phosphine was definitely seen, while another debates whether life is the only possible origin for phosphine on Venus.

Now, a pair of planetary scientists suggest explosive volcanic eruptions could also spew phosphine into the Venusian atmosphere. “We may be witnessing active volcanism on Venus,” study lead author Ngoc Truong, a planetary scientist at Cornell University in Ithaca, New York, told 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.

The scientists found that volcanism on Venus could potentially bring small amounts of phosphorus-loaded compounds known as phosphides from deep in the mantle layer of the planet to the surface. Explosive volcanic eruptions could then spew these phosphides — in the form of volcanic dust — into the atmosphere, where the chemical could react with sulfuric acid to form phosphine.

In order 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.