Scientists have made a significant discovery regarding one of Uranus’ moons, suggesting that Ariel may have once harbored an ocean approximately 100 miles deep. This depth is about 40 times greater than that of the Pacific Ocean. The findings, published in the journal Icarus, indicate that Ariel could still contain remnants of this ancient ocean.
New computer simulations propose that Ariel’s orbit was once more elliptical, which would have allowed Uranus‘ gravitational pull to create tidal heating. This process would have generated enough internal heat to melt parts of Ariel’s icy crust, leading to the formation of an ocean beneath the surface. According to Caleb Strom, the first author of the study, the tidal forces could explain the moon’s surface features, including unexplained cracks and deformations.
These geological features—such as wide canyons, long fractures, and smooth plains—were first documented in images captured by NASA’s Voyager 2 spacecraft during its flyby in 1986. Strom remarked, “It is less that the ocean is causing the cracks than that the ocean is a result of the tidal heating that would also create a thin ice shell, subject to flexing.” This suggests that both a subsurface ocean and a thin ice shell could coexist, as part of the ice shell would be expected to melt.
If these findings are confirmed, Ariel joins a growing list of icy moons in the outer solar system believed to possess liquid water beneath their surfaces. Similar to Saturn‘s Enceladus and Jupiter‘s Europa, Ariel could have previously possessed conditions conducive to the emergence of life. Understanding the thermal history of Ariel could provide insights into how habitable environments can form far from the sun.
Uranus, located 1.8 billion miles from Earth, has recently attracted attention due to the discovery of a new moon, raising its total to 29. For years, scientists considered this icy planet merely a featureless orb. However, fresh studies and data from the James Webb Space Telescope have revealed a more complex and intriguing composition, primarily consisting of water, methane, and ammonia surrounding a small rocky core.
The new study on Ariel follows a previous paper by the same research team that examined Miranda, another moon of Uranus. Co-author Tom Nordheim from the Johns Hopkins University Applied Physics Laboratory stated, “We are finding evidence that the Uranus system may harbor twin ocean worlds.” He emphasized the need for further exploration of the Uranus system to verify these findings.
The tidal forces that may have led to the formation of an ocean within Ariel likely occurred 1 to 2 billion years ago, as the moon’s orbit resonated with another Uranian moon. This gravitational synchronization, known as resonance, can be disrupted over time. Once this resonance ceased, Ariel’s orbit likely became more circular, allowing the hypothetical ocean to begin refreezing.
Researchers suspect that many of Uranus’ moons might be concealing oceans beneath their icy layers or may have previously hosted such bodies of water. Spectroscopic analysis of Ariel’s surface has indicated the presence of ammonia and carbon compounds. These substances degrade rapidly in space, suggesting that they likely originated from within the moon relatively recently. This supports the notion that Ariel’s surface and interior continue to interact, possibly through processes like cryovolcanism, in which water or ammonia erupts from underground reservoirs.
Strom noted that while the cracks on Ariel’s surface could also have formed from other processes, such as the thickening of the ice shell due to freezing water, the potential for cryovolcanism remains a topic of debate among planetary scientists. “Cryovolcanism is a lot more controversial since we don’t really know how it works,” Strom explained, acknowledging that some scientists are skeptical of its occurrence.
The ongoing research into Ariel and its potential ocean not only enriches our understanding of the Uranus system but also raises intriguing questions about the possibility of life on distant celestial bodies.
