In the past, Uranus and Neptune have been classified as “ice giants,” the solar system’s two most distant planets, which we thought of as being made up primarily of water, ammonia, and methane ices under large atmospheric layers. But a report that came out in May 2026 in the journal Astronomy and Astrophysics is turning that idea on its head, which puts forth that, in fact, both planets may contain much more rock than ice, thus it may rewrite a basic tenet of planetary science.
What the Research Found
In the study, the research team, directed by Yamila Miguel from the Netherlands Institute for Space Research, created a model that showed the inner components of two planets. The research found that Uranus and Neptune’s outermost layers contained rocks and gases while lacking ice. Silicate clouds developed in the atmosphere because of the temperature, which transformed into solid matter and caused rocks to form. The research found that heavy-element rocks existed in the study area at an average rate of 60 percent.
Rethinking Planetary Classification
This research idea was based on the recent discovery that trans-Neptunian objects, or objects orbiting around Neptune, are not as icy as people first thought, leading them to wonder if Uranus and Neptune have similar properties. The consequences are massive: Miguel suggests the planets should actually be reclassified, with “minor giants” being a more accurate classification for the planets. Another study from 2025, performed by the University of Zurich, questioned the popular “ice giant” hypothesis and suggested that the structure of both planets is less icy than originally thought. The planets have ice within them; however, it has been agreed upon that they are much less icy than believed before.
