Speculations about lightning on Venus have been around for a long time. Scientists have argued for and against the possibility of lightning on the runaway greenhouse planet.
Now, findings from a recent study suggest that this phenomenon is a rarity.
Venus is one of the four terrestrial planets and the second planet from the Sun. It is the hottest planet in the solar system with temperatures that can melt lead, making it unable to support life.
In a new discovery about the cloud-swaddled planet, researchers from the University of Colorado Boulder have determined that lightning would be rare on Venus if it exists at all.
The team came to this conclusion by analyzing data obtained from NASA’s Parker Solar Probe, which is the first spacecraft to touch the sun.
Harriet George, lead author of the published paper and a postdoctoral researcher at the University’s Laboratory for Atmospheric and Space Physics, explained the findings.
“There’s been debate about lightning on Venus for close to 40 years. Hopefully, with our newly available data, we can help to reconcile that debate,” said George.
The Parker Solar Probe is a space mission designed to explore the Sun. Since its launch in 2018, the mission spacecraft has leveraged advanced technology and autonomy to withstand the radiation and heat from the sun.
How can a spacecraft that is designed for solar exploration observe Venus? Well, it already has. The Parker Solar Probe passed by Venus in February 2021, approaching within 2,400km.
Using the PSP/FIELDS Experiment, a set of electric and magnetic field sensors on the spacecraft, the scientists were able to analyze the planet’s atmospheric conditions.
The Parker Solar Probe detected whistler waves in the thick, cloudy atmosphere of Venus. If whistlers are restricted to Earth, why were they found in Venus?
The researchers sought answers by analyzing the data obtained from the flyby. Interestingly, they found disruptions in the weak magnetic field of Venus. These disruptions are called magnetic reconnection and can have explosive effects.
Further analysis of the whistlers revealed that they move downward rather than upward and out of the atmosphere. According to David Malaspina, a co-author of the study, this finding is different from what “everybody had been imagining for the last 40 years.”
Whistler waves are very low-frequency electromagnetic waves that are produced by lightning. As the name implies, they make whistling tones that are audible enough to be picked up by the headphones of the radar operators.
Although whistler waves are common on Earth, they rarely occur on Venus. They were first detected in 1978 by NASA’s Pioneer Venus spacecraft. Some scientists have relied on their existence over the years to argue that Venus might have lightning.
The number of whistler waves picked up on Venus so far suggests that the planet records seven times more lightning strikes than Earth. This is based on the assumption that the whistler waves were caused by lightning.
To get answers, the scientists now look forward to the next time the Parker Solar Probe will pass by the planet. There are already five flybys, and there are two more to go.
“Parker Solar Probe is a very capable spacecraft. Everywhere it goes, it finds something new,” George said.
Finally, the findings from this study are not enough to completely eliminate the chances of lightning existing on Venus. Scientists believe that the analysis of additional whistler wave data will provide more insights sufficient to make a full refutation.
Parker Solar Probe is expected to fly by Venus for the last time in November 2024.
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