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Astronomers discover a giant cloud that has been looming over Venus for 35 years

The atmospheric phenomenon has never been seen anywhere else in the Solar System.

NASA

Venus is often referred to as Earth’s hotter, more sinister sister. The two planets may be similar in size, mass and density, but Venus is way more intense.

Although it is the second closest planet to the Sun, Venus is actually the hottest planet in our Solar System. Venus’ atmosphere is mostly made up of carbon dioxide, and its surface is extremely dry.

Scientists recently discovered another feature to this hellish world, a giant cloud has been lurking over the planet for the past 35 years completely undetected.

The discovery was detailed in a study published this week in the Geophysical Research Letters.

This animation shows the lower clouds on Venus, which are approximately 50 kilometers above the planet's surface.Javier Peralta/JAXA-Planet C team.

In 2016, the Japanese Space Agency's (JAXA) Akatsuki, which has been orbiting Venus for nearly 10 years now, first spotted what appeared to be an atmospheric wave extending over the scorching hot planet. Follow up observations of the strange phenomenon were conducted using NASA's Infrared Telescope Facility in Hawaii, probing the middle and lower layers of Venus' atmosphere.

“If this happened on Earth, this would be a frontal surface at the scale of the planet, and that’s incredible,” Pedro Machado, a researcher at Instituto de Astrofísica e Ciências do Espaço (AI) in Portugal, and one of the authors behind the new study, said in a statement.

The giant cloud extended as far as 4,700 miles across the equator at altitudes between 30 and 35 miles above the surface. Further observations revealed that this cloud has been raging on since 1983, swiping across the entire planet in a mere five days at a speed of 205 miles per hour.

A cloud of this type of magnitude has never been observed before in the Solar System. The team of researchers behind the discovery created computer simulations of the atmospheric phenomenon, but the mechanism that started it and maintained it for the past 35 years remains unknown.

Different atmospheric waves have been found on Venus before, namely the bow-shaped 'Y wave' that extended over 10,000 kilometers long, but this is the first one to be discovered at low altitudes.

This region of the planet is where Venus traps heat, and is responsible for the planet's scorching hot temperatures. Venus' dense atmosphere traps heat the same way greenhouses gases do on Earth, which is why Venus also serves as an eerie look into our planet's future.

Temperatures on Venus reach 870° F, that's hot enough to melt lead.

Therefore, by observing this giant cloud, scientists might get a better understanding of Venus' atmosphere and its interaction with the planet's surface.

"This atmospheric disruption is a new meteorological phenomenon, unseen on other planets. Because of this it is yet difficult to provide a confident physical interpretation,"Javier Peralta, a researcher at JAXA, and lead author of the new study, said in a statement. "But we do not have doubts that its cyclical effects over the clouds’ properties and distribution of atmospheric aerosols are key pieces missing to complete the complex puzzle of Venus.”

Astronomers will conduct further observations of the giant cloud hoping to get a better understanding of the mechanism that governs its cycle. However, they believe that it may be the physical manifestation of an atmospheric Kelvin type wave.

Kelvin waves are a type of atmospheric gravity waves.

Abstract: Planetary‐scale waves are thought to play a role in powering the yet unexplained atmospheric superrotation of Venus. Puzzlingly, while Kelvin, Rossby, and stationary waves manifest at the upper clouds (65–70 km), no planetary‐scale waves or stationary patterns have been reported in the intervening level of the lower clouds (48–55 km), although the latter are probably Lee waves. Using observations by the Akatsuki orbiter and ground‐based telescopes, we show that the lower clouds follow a regular cycle punctuated between 30°N and 40°S by a sharp discontinuity or disruption with potential implications to Venus's general circulation and thermal structure. This disruption exhibits a westward rotation period of ∼4.9 days faster than winds at this level (∼6‐day period), alters clouds' properties and aerosols, and remains coherent during weeks. Past observations reveal its recurrent nature since at least 1983, and numerical simulations show that a nonlinear Kelvin wave reproduces many of its properties.
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