(CNN) When scientists recently took a closer look at archival images of the surface of Venus, they discovered something new: evidence of volcanic activity on Earth’s “twin.”

NASA’s Magellan spacecraft took the pictures in the early 1990s when it was orbiting our nearest planet, which is similar to Earth in size and composition.

A new analysis of the orbiter’s perspective of a region near the Venusian equator reveals a volcanic vent that changed shape and increased dramatically in size over a period of eight months.

Images of the crater represent the first direct geological evidence of recent volcanic activity on the surface of Venus, according to the researchers. A study detailing the findings was published in the journal Wednesday Sciencesand was presented at the 54th Lunar and Planetary Science Conference in The Woodlands, Texas.

The Magellan mission became the first to image the entire surface of Venus before the spacecraft was deliberately plunged into the planet’s hot, toxic atmosphere in 1994 to collect a final set of data. But a fleet of new missions will be heading to Venus within a decade, including Truth, honestyVenus emissivity, radio science, InSAR, topography, and spectroscopy message.

Active volcanic landscape

The probe will use its instruments to unlock the secrets behind a planet similar in size to Earth covered in volcanic plains and an inhospitable atmosphere.

“I was inspired by NASA’s selection of the VERITAS mission to search for recent volcanic activity in the Magellan data,” study lead author Robert Herrick, a research professor at the University of Alaska Fairbanks and member of the Veritas science team, said in a statement.

“I really didn’t expect to be successful, but after about 200 hours of manually comparing images of different Magellan orbits, I saw two images of the same area eight months apart showing telltale geological changes caused by a volcanic eruption.”

Herrick detected changes in images of Atla Reggio, a vast highland region that includes two of Venus’ largest volcanoes, Ozza Mons and Maat Mons. Both are similar to the two largest volcanoes on Earth, Herrick said, but because they have lower slopes, the two volcanoes on Venus are more spread out.

Note that a vent on the north side of a domed volcano that was part of Maat Mons changed hands between February and October 1991.

Magellan’s image of the vent from February showed a circular vent spanning less than 1 square mile (2.2 square kilometers) with steep inner sides and areas of drained lava on the slopes.

Eight months later, the spacecraft took another image showing a very different, distorted-looking hole, nearly doubled in size and filled almost to the brim with a lava lake.

Although the differences seem obvious, the two images were taken from opposite angles and perspectives and at a much lower resolution than the images taken by the cameras on the spacecraft today.

3D mapping of Venus

Herrick worked with Scott Hensley, Veritas project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, to create computer models of the vent to determine the likely cause of the changes.

“Only two simulations matched the images, and the most likely scenario is that volcanic activity occurred on the surface of Venus during the Magellan mission,” Hensley said. “While this is just a data point for an entire planet, it confirms the presence of recent geological activity.”

Researchers believe that the pyroclastic flow Magellan witnessed in 1991 was similar to what was released by the Kilauea eruption in Hawaii in 2018.

“This was looking for a needle in a haystack with no guarantee that the needle was there,” Herrick said. “Finding a change that could be clearly confirmed as real was an absolute surprise. We were pretty sure that Venus was volcanically active, but we didn’t know if eruptions occurred every few months or years or once every 10,000 years or more. All could be The options fit with the current data. Unless incredibly lucky, we now know that the frequency is every few months or so, similar to the large family of Earth’s basaltic volcanoes like Hawaii, Galapagos Islands, Canary Islands, etc.”

While it is possible that the earthquake caused the walls of the volcanic vent to collapse, researchers believe that such activity may have also caused the eruption.

Volcanoes act like windows into the planet’s interior, allowing scientists to understand more about the factors that influence its ability to be a habitable world. Missions like VERITAS will help scientists gain a better understanding of Venus, just as Magellan did decades ago.

The new mission will be equipped with radar to create 3D global maps of Venus and capture details about its surface composition, gravitational field, and what happened in the planet’s past.

“Venus is a mysterious world, and Magellan has raised so many possibilities,” Jennifer Witten, VERITAS Deputy Associate Principal Investigator and Assistant Professor of Earth and Environmental Sciences at Tulane University in New Orleans, said in a statement. “Now that we are absolutely certain that the planet experienced a volcanic eruption only 30 years ago, this is a small preview of the amazing discoveries that VERITAS will make.”