Scientists believe Uranus and Neptune are 'ice giants,' but a new study hints at something else

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Uranus and Neptune have been a source of mystery due to their remote locations and the limited data available. Now the mystery may have a solution

In the 1980s, NASA's Voyager made a flyby past Uranus and Neptune and helped scientists conclude that the two planets are rich in frozen water.

Now, a new study has suggested that these planets may also contain substantial amounts of methane ice, which could help solve the puzzle of how they were formed.

Mystery in space

Uranus and Neptune have been a source of mystery due to their remote locations and the limited data available

Astronomers have developed models based on these observations, proposing that the planets have a thin hydrogen and helium envelope, a layer of compressed superionic water and ammonia, and a rocky core, with the water component giving them their "ice giant" designation.

However, the new study challenges this view by considering the formation process of Uranus and Neptune. As these planets took shape from the primordial dust cloud around the young sun, they would have gobbled up planetesimals — objects similar to present-day comets, reports space.com. 

These planetesimals are believed to be carbon-rich, unlike the assumed water-rich building blocks in current models.

So "How is it possible to form an icy giant from ice-poor building blocks?" asks planetary scientist at Technion-Israel Institute of Technology Uri Malamud, the study's lead author.

To address this discrepancy, the researchers constructed hundreds of thousands of models of Uranus and Neptune's interiors, considering various compositions including iron, water, and methane. They found that models incorporating methane, either as solid chunks or in a mushy state under extreme pressure, best matched the planets' observed traits.

The presence of methane could help resolve the paradox of how these "ice giants" formed. The scientists propose that the methane ice formed when hydrogen in the growing planets reacted chemically with the carbon in the accreted planetesimals, under the intense heat and pressure that would have been prevalent in the developing planets.

While the study sheds light on the potential composition of Uranus and Neptune, verifying the presence of methane would be challenging, said Malamud. They hope that future missions, such as those proposed by NASA, could provide further insights into these enigmatic planets and help confirm the findings of this study.

(With inputs from agencies)

Moohita Kaur Garg

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