Latest news with #gasgiants
Yahoo
23-06-2025
- Science
- Yahoo
What would happen if you tried to land on a gas giant?
Our solar system contains three types of planets. Between the four terrestrial planets–Mercury, Venus, Earth, and Mars–and the distant ice giants of Neptune and Uranus, sit two gas giants: Saturn and Jupiter. These planets are mostly composed of hydrogen and helium gas. Researchers now appreciate that gas planets are more complex than first thought. New findings have implications for our understanding of how these planets formed and will help design future missions to potentially visit them. Gas giants originate from one of two processes. The first method is called core accretion, explains Ravit Helled, a professor of theoretical astrophysics at the University of Zürich. This starts with the birth of a new star, when molecular clouds collapse under gravitational pressure. Whorls of gas–called protoplanetary disks–start to spin around these new stars. Within these gas disks will be heavier particles–dust, rock, or any elements heavier than helium. These particles can clump together and then suck in gas from the surrounding disk, forming a giant planet mainly composed of gas. A second method that may form gas giants called disk instability–this is a newer theory that still causes some controversy among planetary theorists. According to this idea, when massive protoplanetary disks cool down, they become unstable and can produce clumps of rock and gas that evolve into gas giants. Importantly, this proposed formation process happens much more quickly than core accretion. Helled says that Saturn and Jupiter likely formed via core accretion, but that disk instability may 'explain very massive planets at large orbits or giant planets around small mass stars.' Regardless of how they form, the structure of gas giants is nothing like that of terrestrial planets like Earth. Jupiter and Saturn don't have a surface in the same way Earth does. Instead, their atmosphere simply gets thinner until there isn't enough density left to call the surrounding air part of the planet anymore. 'There is no location where you can say, okay, this is where the planet stops,' says Helled. A spaceship attempting to 'land' on Jupiter's 'surface' would have to overcome some significant obstacles. Once you enter the cloud of gas that roughly marks the beginning of a giant like Jupiter, temperature and pressure steadily increase as your head toward the planet's core, and gaseous hydrogen and helium morph into liquid form. While our solar system's gas giants are far from the sun, the core of a gas giant is likely to be incredibly hot–Jupiter's is estimated at around 43,000 degrees Fahrenheit. You'd also have to pass through the thick clouds of ammonia found in Jupiter's upper atmosphere. If you make your ship from tough stuff–tougher than any known substance on Earth–that could survive these conditions, it might make it to a gas giant's core. What it would find there in the alien murk is still unclear. 'For decades, it was assumed that there was a defined core,' says Helled. Recent probe missions, like Juno and Cassini, have orbited Jupiter and Saturn, respectively. The information these probes sent back has changed that view. 'We now think that they have what we call fuzzy or diluted cores,' says Helled. This means that there isn't a clear transition point between the upper layers of liquid gas and liquid hydrogen and helium and the planet's core. In truth, Juno and Cassini's data has revolutionized our understanding of these planet's structures. Helled explains that they likely have complex heat and composition gradients. Jupiter is famously wracked with massive storms, like the Great Red Spot, which produces winds up to 425 mph (640 km/h). Some of these shifts can produce dramatic phenomena. Jupiter and Saturn likely have regions in which helium gas separates from hydrogen. Here, the helium becomes a rain of droplets that pour towards the planet's core. These insights can reveal more about our solar system's giants, as well as similar planets outside our solar system. 'Now we realize that some of the simple assumptions that we've made to model these planets are wrong, and we need to modify the models,' says Helled. This story is part of Popular Science's Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you've always wanted to know? Ask us.
The Guardian
10-06-2025
- Science
- The Guardian
Astronomers left puzzled by high-altitude clouds forming on young planet
Should humans ever venture to a particular planet that circles a sun-like star in the constellation of the fly, they would do well to keep an eye on the weather. The thick slabs of cloud that blot the planet's skies are mostly made from mineral dust, but astronomers suspect there may be iron in them, too, which would rain down on the world below when the clouds break. Astronomers spotted the high-altitude clouds when they trained the James Webb space telescope (JWST) on the young star system, which lies 307 light years away in the deep southern sky. The star, YSES-1, is a newbie by cosmic standards, a mere 1m years old compared with the 4.6bn-year-old sun. The star is circled by two gas giants, both still forming and both larger than Jupiter, the biggest planet in the solar system. Dr Kielan Hoch, an astrophysicist at the Space Telescope Science Institute in Baltimore, Maryland, said the planetary system's youth made it a prime target for astronomers to learn more about the early evolution of planets around faraway stars. 'There's a small handful of multiplanet systems that have been directly imaged,' Hoch said. 'And they are a unique laboratory to test planet formation theories as they formed in the same environment.' 'Both planets are still forming, which is why they are still bright enough for us to detect,' she added. 'The light we are seeing is from their formation as they begin to shrink and condense.' When the team began their observations they were surprised to find both planets in the telescope's field of view, giving them information on two worlds for the price of one. The outer planet, YSES-1c, is the smaller of the two worlds, and about six times the mass of Jupiter. The telescope revealed high-altitude clouds in the planet's atmosphere, but instead of being made from water vapour as on Earth, the clouds consist of magnesium silicate dust grains and perhaps some iron. 'The iron would indeed precipitate out,' Hoch said. The astronomers described the observations as the first direct detection of such clouds on a planet circling a sun-like star. Further data revealed a disc of material made up of trillions of tonnes of dust particles around the larger inner world, YSES-1b, about 14 times the mass of Jupiter. The findings were published in Nature. Hoch said the disc around the inner planet was a 'puzzle for formation theories' since both planets must have formed in the same environment. 'Why did YSES-1b hold on to material around it while YSES-1c did not?' she said. An added mystery is why a 16m-year-old planet still has a disk of material swirling around it. Astronomers' theories of planet formation suggest that any encircling dust should have settled after the first 5m years. 'We wouldn't expect the planets to look so different from one another if they formed in the same protoplanetary disk,' Hoch said. 'JWST is providing an immense amount of data to continue to refine models and improve our understanding.' The $10bn telescope has transformed astronomy since it launched in December 2021 from Europe's Spaceport in French Guiana. The flagship mission has peered back to the first galaxies that lit up the cosmos, spied strange new worlds, and witnessed black holes colliding. It has even spotted tantalising, if controversial, hints of life beyond Earth.
