By Jonny Lupsha, Wondrium Staff Writer
Scientists looking for alien life have turned their telescopes from Venus to Jupiter. Venus’s atmosphere holds far too little water to support any kind of microbial life, despite a recent discovery of molecules that suggested otherwise. Jupiter, a gas giant, holds atmospheric potential.
A new study has concluded that Venus’s atmosphere is simply too devoid of water molecules to house even the toughest known microbial life on Earth. Jupiter, our solar system’s largest gas giant, has a layer of clouds that hold enough water. While that doesn’t mean that microbial life definitely exists on Jupiter, the planet does have the proper water requirements.
Jupiter’s distance from the Sun is 5.2 times that of Earth. In her video series A Field Guide to the Planets, Dr. Sabine Stanley, a Bloomberg Distinguished Professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins University, said Jupiter’s changing appearance is just one of its atmosphere’s wonders.
Giant Planet, Colossal Storms
“At a planetary scale, the most striking features of Jupiter’s atmosphere are the white and brownish-red bands and giant storms,” Dr. Stanley said. “We perceive these colors because of the tiny smattering of heavier elements that are mixed in with the hydrogen and helium.
“Compounds made from these heavier elements can produce the vibrant colors we see, helping us to distinguish features and motions in Jupiter’s atmosphere.”
One example of this, according to Dr. Stanley, is that the white regions in Jupiter’s horizontal bands get their color from ammonia clouds. Meanwhile, other bands are brownish-red because they’re full of sulfur-rich compounds. Like other planets, Jupiter is hotter towards its center and cools towards space. So as hot materials rise and cool, gas clouds form at the point in the atmosphere in which they reach their dew points.
“When we look at Jupiter, different cloud bands therefore show us different altitudes in the atmosphere and different temperatures,” Dr. Stanley said. “The white ammonia bands occur at higher altitudes and are cooler; these white clouds are the tops of rising hot plumes from the deep interior.
“Warmer and lower in the atmosphere are the sulfur-rich brownish-red bands, which occur where cooler material is sinking back into the interior at lower altitudes.”
The Eye in the Sky
Relatively regular horizontal bands of white and brownish-red circle Jupiter, which is a common feature of rapidly rotating fluids. Just like the jetstreams of Earth, Jupiter’s rotation organizes the motion of its atmosphere, although in Jupiter’s case it results in those colorful bands.
“One obvious deviation from the banded structure is Jupiter’s Great Red Spot, a giant oval storm at a latitude of 22 degrees south,” Dr. Stanley said. “The Great Red Spot is similar to the location of Madagascar on Earth, except the Great Red Spot is the size of all of Earth. The storm has an oval shape, with fastest winds on its outer edge swirling about the center at over 250 miles per hour.”
Continuously observed since at least the 1830s, there’s a chance that the Great Red Spot may have been observed in the late 1600s. However, it has been shrinking, and could disappear in another 70 years, if it continues to shrink at its current rate.
In 1995, the Galileo probe taught us plenty about Jupiter. It fell through 400 kilometers of atmosphere in three minutes, then opened a parachute and took measurements for an hour, which it sent back to Earth. It was finally crushed by an atmospheric pressure of 22 bars.
“More details on the depths of the atmosphere came in 2017 and 2018, when Juno mission scientists determined that the Great Red Spot is about 350 kilometers deep,” Dr. Stanley said. “For comparison, that’s 20 times the depth of a major hurricane on Earth. Moreover, Juno scientists determined that the banded jet streams extend down to a whopping 3,000 kilometers.”
Somewhere between the upper atmosphere and Jupiter’s “fuzzy core” of heavy elements, hydrogen, and helium, the water conditions are just right for microbial life.