Mysterious crowns on Venus. Scientists surprised by research results

“Coronas do not exist on Earth today; however, they may have existed when our planet was young and before plate tectonics was established,” said Gael Cascioli, lead author of the new Venus study and a scientist at the University of Maryland, Baltimore County and NASA’s Goddard Space Flight Center in Greenbelt. “By combining gravity and topographic data, we have gained important new insight into possible subsurface processes that are currently shaping Venus’ surface,” he explained in a NASA release.

Anna Gülcher, a researcher at the University of Bern in Switzerland and co-author of the study, comments: "Coronae are abundant on Venus. They are very large structures, and scientists have proposed different theories over the years about how they were formed. The most exciting thing about our study is that we can now say that there are most likely different and still active processes driving their formation. We believe that the same processes could have been at work early in Earth's history."

Similarities and Differences Between Earth and Venus

Venus, the second planet in the Solar System, is classified as a rocky planet (a terrestrial planet). It is sometimes called a twin planet to Earth. It is similar in size and mass. There are also indications that Earth and Venus may have a similar internal structure. However, Venus does not have the tectonic plates that are present on Earth. Despite this, tectonic processes do occur there (and the latest study shows that they are more numerous than we expected).

What definitely distinguishes Earth from Venus is the atmosphere. The atmosphere of Venus consists mainly of carbon dioxide and a small amount of nitrogen. It is covered with an opaque layer of sulfuric acid clouds, which reflects light well, which as a result does not allow the observation of the surface of Venus from space (in visible light). As a result, the temperature on the surface of this planet reaches 460 degrees Celsius and is higher than the temperature on the surface of Mercury (which is twice as close to the Sun). The results of studies suggest that there may have once been water on Venus, but it evaporated due to the greenhouse effect.

What are crowns on Venus?

Venus' coronae (English-language publications use the word "corona" for singular and "coronae" for plural) are huge, circular structures surrounded by rings of fractures that are widely distributed across the planet's surface. They are volcanic in origin. They are thought to form where a plume of hot, rising material from the planet's mantle rises, pressing down on the lithosphere above it (the lithosphere includes the planet's crust and the uppermost part of its mantle). They range in size from a few dozen to hundreds of miles (1 mile is 1.6 km).

In addition to the crowns, characteristic features of the Venusian landscape not found on Earth include farra, i.e. flat-topped volcanic domes 20 to 50 km in diameter and 100–1000 m high, resembling pancakes (in English farra are also called pancake domes), and arachnoids, structures composed of radial and concentric cracks resembling spider webs.

How do scientists study Venus? The importance of the Magellan probe

For years, one of the biggest barriers to studying Venus was its thick atmosphere, which made it impossible to observe in visible light. The situation improved in the 20th century thanks to the use of spectroscopy, ultraviolet and radar. In the second half of the 20th century, space missions began to explore Venus. One of the key missions was the American Magellan probe, which was launched from Earth on May 4, 1989. Its task was to map Venus using radar. It obtained images of relatively high resolution, significantly exceeding previous measurements. The data collected by the probe concerned both the topography of Venus and its gravitational field. It was this data that became the basis for the latest studies of the coronae on Venus.

Scientists have studied 75 crowns on Venus. How?

To determine the most likely scenario for Venus's corona formation, researchers created a 3D model that simulated the flow of hot material inside the planet. It was a kind of virtual experiment that tested different scenarios for corona formation. The results were then compared with data from the Magellan probe. The gravity data, which measured the strength of gravity at different points on the planet's surface, proved groundbreaking, NASA said. "This is because denser material exerts a stronger pull on nearby objects, while less dense material exerts a weaker pull. The data helped scientists detect hidden plumes of hot, less dense material rising from deep inside Venus, something that surface maps alone could not reveal," NASA said in a statement.

Of the 75 coronae studied, 52 showed signs of subterranean forces, suggesting that tectonic activity on Venus may be more widespread than previously thought. The results of the study of the coronae on Venus are published in the journal Science Advances.

NASA's Venus Exploration Plans – VERITAS Mission

Scientists studying the coronae of Venus are part of the team working on the VERITAS mission, which is set to launch a spacecraft to Venus. The earliest possible date is 2031. “VERITAS gravity maps of Venus will improve resolution by a factor of at least two to four, depending on the location. This will be a level of detail that could revolutionize our understanding of Venus’ geology and the implications for the early Earth,” said Suzanne Smrekar, co-author of the Venus corona study and VERITAS principal investigator.