What can the water in Jupiter’s atmosphere teach scientists about the planet’s composition? This is the goal of a study recently published in the *Proceedings of the National Academy of Sciences*. A team of scientists examined the distribution of water in Jupiter’s atmosphere. This study has the potential to help scientists better understand Jupiter’s atmospheric dynamics, composition and evolutionary history.
For the study, researchers used a series of computer models to simulate Jupiter’s water cycle, particularly in its mid-latitudes. This came after NASA’s Juno spacecraft, which is currently orbiting Jupiter and some of its moons, observed irregularities that could extend deep into Jupiter’s atmosphere. Using the models to explain these irregularities, the researchers suggest that Jupiter’s high rotation speed could cause water to rain through its atmosphere into the layers beneath the tops of primary clouds. They suggest that this causes precipitation (moisture) to increase with depth. As for rotation, although Earth takes 24 hours to rotate once, Jupiter only takes 10 hours to do so, despite being about 318 times more massive than Earth.
These findings could not only reveal more about Jupiter’s atmosphere, but also shed light on how water might have gotten to Earth, since Jupiter has long been thought to be the first planet to form in the solar system. This is because Jupiter’s immense gravity may have diverted water-rich asteroids to Earth, or its migration into the inner solar system may have redistributed the protoplanetary disk that formed Earth and the other rocky planets.
“While we focus on Jupiter, we are ultimately trying to develop a theory of water and atmospheric dynamics that can be broadly applied to other planets, including exoplanets,” said Dr. Huazhi Ge, a postdoctoral researcher at the California Institute of Technology and lead author of the study.
As of this writing, more than 6,000 exoplanets have been confirmed by NASA, with about a third of them being gas giants like Jupiter. Therefore, the largest planet in our solar system has served and should continue to serve as a suitable analogue for the study of exoplanets and their dynamic atmospheres. While Jupiter orbits about 778 million kilometers (484 million miles) from our Sun and takes nearly 12 years to complete an orbit, several of the confirmed gas giant exoplanets have been observed to orbit much closer and require only days to complete an orbit, called hot Jupiters and ultrahot Jupiters.
An example of a hot Jupiter is HD 189733 b, which is located about 64.5 light-years from Earth and is estimated to orbit its star in just 2.22 days. For comparison: Mercury is the closest planet to the sun in our solar system and takes 88 days to complete one orbit. Due to its extremely close orbit, HD 189733 b’s atmosphere is very dynamic, including supersonic winds of up to 2 kilometers per second (7,200 kilometers per hour/4,474 miles per hour) and glass rainstorms.
Despite these results, it is important to note that water vapor makes up about 0.25 percent of Jupiter’s atmosphere, being largely dominated by hydrogen (~89 percent) and helium (~10 percent). But its atmosphere contains trace gases, including methane, ammonia, neon and argon, to name a few. Still, these findings could provide insights into the formation and evolution of the solar system, including how water got to Earth, which is the reason for life as we know it on our little blue world.
What new insights into Jupiter’s atmospheric water distribution will researchers gain in the coming years and decades? Only time will tell, and that’s why we do science!
As always, keep up the science and keep looking up!
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