Contrary to assumptions made decades ago, there may be little or no lightning in Venus’ atmosphere, according to researchers’ analysis of data collected by NASA’s Parker Solar Probe.
In 1978, the Pioneer Venus probe orbited the planet and detected what appeared to be electromagnetic waves. ”whistler” Waves hundreds of miles above the Earth’s surface. Whistlers are low-frequency radio waves that travel along magnetic field lines and ripple through the atmosphere. On Earth, they are often caused by lightning.
Astronomers have proposed that the presence of Whistler waves on Venus is evidence of lightning occurring within its clouds. But a group of researchers led by the University of Colorado Boulder is questioning that interpretation.
“Lightning on Venus has been debated for nearly 40 years.” gave an opinion Harriet George, lead author of the new study and a postdoctoral fellow in the school’s Institute of Atmospheric and Space Physics. “We hope to leverage the newly available data to help shape this discussion.”
George and her colleagues analyzed data collected by the Parker Solar Probe. The spacecraft has now completed five years of exploration to study the effects of the solar wind. The spacecraft’s path to the Sun included seven passes over Venus to perform gravity-assisted maneuvers, allowing it to accelerate to 430,000 miles per hour (690,000 km/h). This makes it the fastest man-made object in history.
During its fourth flyby in 2021, the spacecraft’s electric and magnetic field sensors detected dozens of Whistler waves on Venus. The data revealed some strange properties of the waves. The waves were descending toward the planet. On Earth, whistler waves generated by lightning typically propagate outward into space.
“The direction in which the Whistler waves are traveling indicates where they must have formed, which gives us clues about the mechanism,” George explained. register.
“If the waves were caused by lightning or some other atmospheric process, the waves would move away from Venus. The fact that the waves were traveling toward Venus means that the waves could not have been caused by lightning, but by yet another process.” “That means it must have been caused by something in the far reaches of space, perhaps in a region on the planet’s night side called the magnetic tail,” she said.
If lightning occurs frequently on Venus, as astronomers previously thought, the waves would also be accompanied by flashes, but the paper suggests that such events are rare.
“Lightning has not been detected in multiple spacecraft encounters with Venus,” the researchers wrote in their paper. published in diary Geophysical Research Letters.
“These undetected and rare optical observations are consistent with a low Venusian lightning incidence, which is inconsistent with the high incidence of Whistler-derived lightning. We present the results of Whistler’s observations and rule out lightning as a possible source.
Instead, they believe that Whistler waves are due to magnetic reconnection. In magnetic reconnection, Venus’ magnetic field lines break and recombine, releasing a jolt of energy.
Researchers need more data to figure out whether there really is no lightning on Earth, or whether there is only a small amount of lightning, and the Parker Solar Probe will fly 450 miles above Earth. It claims it will rely on data collected during its final flight. surface.
“It’s very rare for a new scientific instrument to reach Venus,” said David Malaspina, a co-author of the new study and an assistant professor in the Department of Astrophysical and Planetary Sciences at the University of Colorado Boulder. “There are not many opportunities to conduct such interesting research.®
