Jupiter’s Great Red Spot continues to baffle astronomers

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Jupiter’s Great Red Spot is an anticyclone swirling around a center of high atmospheric pressure on the gaseous giant for more than 150 years and continues to baffle astronomers globally.

Said to have tumultuous winds peaking at about 400 mph, the gigantic storm in Jupiter is twice as wide as Earth and NASA says that the mystery surrounding the Great Red Spot is mostly Jupiter’s fault. The reason being Jupiter’s clouds obstruct clear observations of its lower atmosphere. Some studies have investigated areas in Jupiter’s lower atmosphere, but orbiting probes and telescopes studying the Great Red Spot can only see clouds scattered high in the atmosphere.

The gaseous behemoth of a planet packs a liquid ocean of hydrogen around its core, and the atmosphere consists mostly of hydrogen and helium. With no solid ground to weaken storms, the Great Red spot continues unabated.

Studies have suggested that Jupiter’s upper atmosphere has clouds consisting of ammonia, ammonium hydrosulfide, and water. However, scientists are not sure exactly how or even whether these chemicals are responsible for the colours like those present in the Great Red Spot.

Trapped between two jet streams, the Great Red Spot is an anticyclone swirling around a center of high atmospheric pressure that makes it rotate in the opposite sense of hurricanes on Earth. Credits: NASA/JPL/Space Science Institute
Trapped between two jet streams, the Great Red Spot is an anticyclone swirling around a center of high atmospheric pressure that makes it rotate in the opposite sense of hurricanes on Earth.
Credits: NASA/JPL/Space Science Institute

Further, scientists also say that these chemicals only form part of the atmosphere indicating that there are other chemicals present that play roles that are yet to be known.

Researchers from NASA – Mark Loeffler and Reggie Hudson – have been performing laboratory studies to investigate whether cosmic rays, one type of radiation that strikes Jupiter’s clouds, can chemically alter ammonium hydrosulfide to produce new compounds that could explain the spot’s color.

Ammonium hydrosulfide is unstable under Earth’s atmospheric conditions, so Loeffler makes his own batch by heating hydrogen sulfide and ammonia together. He then blasts them with charged particles, similar to the cosmic rays impacting Jupiter’s clouds.

“Our first step is to try to identify what forms when ammonium hydrosulfide is irradiated,” Loeffler said. “We have recently finished identifying these new products, and now we are trying to correlate what we have learned with the colors in Jupiter.”

Other experts agree with the leading theory that deep under Jupiter’s clouds, a colorless ammonium hydrosulfide layer could be reacting with cosmic rays or UV radiation from the sun. But Amy Simon, an expert in planetary atmospheres at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said many chemicals turn red under different situations. “That’s the problem,” she said. “Is it turning the right color red?” Under the right conditions, ammonium hydrosulfide might be.

With the Great Red Spot and other reddish parts of Jupiter, coloring may result from multiple factors, as opposed to just ammonium hydrosulfide. “Ideally, what you’d want is a mixture with the right components of everything that you see in Jupiter’s atmosphere at the right temperature, and then irradiate it at the right levels,” Simon said. Ultimately, Simon and Loeffler said solving the Great Red Spot’s mystery will take more experiments combining chemicals under the right temperatures, light exposures and radiation doses. “What we are trying to do is design lab experiments more realistic to Jupiter’s atmosphere,” Simon said.