Witnessing the blood-red fires of a volcanic eruption on Earth is memorable. But it would be extraordinary to see molten rock bleeding from a volcano on another planet. That’s close to what scientists have noticed on Venus: two huge, serpentine lava flows oozing from two different corners of Earth’s neighboring planet.
“When you see something like this, the first reaction is ‘wow,’” says Davide Sulcanese, a doctoral candidate at the Università d’Annunzio in Pescara, Italy, and author of a study reporting the discovery in the journal Nature Astronomy. published on Monday.
Earth and Venus were forged at the same time. Both are made of the same primordial material, and both are of the same age and size. So why is Earth a paradise full of water and life, while Venus is a scorched hell with sour air?
Volcanic eruptions tinker with the planetary atmosphere. One theory holds that centuries ago, several apocalyptic eruptions caused a runaway greenhouse effect on Venus, turning it from a temperate, swampy world into an arid desert of burnt glass.
To better understand its volcanism, scientists hoped to catch a Venusian eruption red-handed. But while the planet is known to have been smothered by volcanoes, an opaque atmosphere has prevented anyone from seeing an eruption like the ones spacecraft have spotted on Io, Jupiter’s hypervolcanic moon.
In the 1990s, NASA’s Magellan spacecraft used cloud-penetrating radar to survey most of the planet. But at the time, the relatively low-resolution images made detecting freshly molten rock a difficult task.
Using modern software to study Magellan’s data, scientists have now discovered two unequivocal lava flows: one tripping the flank of Sif Mons, a broad shield volcano, and the other snaking its way through a western part of Niobe Planitia, a flat plain pockmarked with numerous volcanic mountains.
Many planetary scientists thought Venus was bustling with eruptions. “But it’s one thing to strongly suspect it and quite another to know it,” says Paul Byrne, a planetary scientist at Washington University in St. Louis, who was not part of the new study.
Venus lacks Earth’s plate tectonics. But the similar rocky composition and similar size suggest that something is still cooking within the second planet from the Sun – and that it should be volcanically active.
There is circumstantial supporting evidence: volcanic gases linger in Venus’ sky, and the way parts of the planet glow suggests they were painted over by lava in the recent geological past.
Direct evidence of volcanic fury finally, and surprisingly, emerged in 2023, when researchers spotted a volcanic vent in ancient Magellan data that doubled in size and possibly filled with lava. Other scientists still longed for signs of an unequivocal lava flow, an almost literal smoking gun.
Mr. Sulcanese granted their wish. He found bright, river-like spots on Sif Mons and Niobe Planitia in later Magellan survey images that were not present in earlier data. After carefully ruling out other possibilities, including landslides, his team concluded that lava was the only reasonable explanation.
“Magellan is the gift that keeps on giving,” says Stephen Kane, a planetary astrophysicist at the University of California, Riverside, who was not involved in the new research.
Both lava flows are comparable in size to the output of Hawaii’s Kilauea volcano during its three-month eruption in 2018. And based on these two eruptions, the study authors estimate that there is significantly more eruptive activity than previously thought – and that this also happens. elsewhere on the planet in the present day.
“Venus is active,” says Giuseppe Mitri, an astronomer also at the Università d’Annunzio and author of the study.
More importantly, volcanically, Venus is “similar to Earth,” says Anna Gülcher, a planetary scientist at the California Institute of Technology, who was not involved in the work.
The result also complicates the preliminary detection of phosphine in Venus’ atmosphere; Phosphine is a substance that on Earth is usually associated with living things. But other explanations for its possible presence on Venus could not be ruled out. Volcanic activity can also make phosphine, but refutations of that idea have suggested that Venus simply doesn’t have enough volcanism to make it.
“Well, apparently it is,” said Dr. Kane.
The only way to find better answers—about phosphine, Venus’s volcanic cadence, its cataclysmic transformation—is to revisit the planet. Fortunately, a fleet of new spacecraft will do just that in the 2030s.
While we wait, Magellan’s memories will continue to offer unexpected gifts.
“We can start to see Venus as a living, breathing world,” said Dr. Byrne.