NASA and University of Oxford scientists discovered that Uranus generates its own internal heat, contradicting data from NASA’s 1986 Voyager 2 mission, which showed the ice giant was virtually “thermally dead.” The discovery answers a long-standing question regarding why Uranus looks so different from the other large planets in our solar system.
Two independent research teams used advanced computer modeling and decades of observational data to reach similar conclusions. The NASA team, coordinated by Amy Simon at Goddard Space Flight Center, discovered that Uranus emits around 15% more energy than it gets from the Sun. A different study conducted by University of Houston researchers led by Xinyue Wang found that the planet emits around 12.5% more heat than it absorbs.
“Since Voyager 2’s flyby, everybody has said Uranus has no internal heat,” explained Amy Simon from NASA’s Goddard Space Flight Center. “But it’s been really hard to explain why that is, especially when compared with the other giant planets (in our own solar system)”. The research teams used computer models that integrated decades of atmospheric observations from ground-based and space-based telescopes, including NASA’s Hubble Space Telescope and NASA’s Infrared Telescope Facility. These models accounted for factors such as hazes, clouds, and seasonal changes that affect how sunlight is reflected and how heat escapes from the planet.
Uranus is warmer than we thought.
New computer modeling techniques revealed that Uranus generates internal heat. This is similar to our solar system’s other gas giants, like Jupiter or Neptune. https://t.co/OpsOIwXYc9 pic.twitter.com/ffwnZqSjNP
— NASA (@NASA) July 22, 2025
The discovery shows that Uranus is “still slowly losing leftover heat from its early history, a key piece of the puzzle that helps us understand its origins and how it has changed over time,” according to Wang. This interior heat most likely represents residual energy from the planet’s formation 4.5 billion years ago. However, Uranus still emits less internal heat than other big planets. Jupiter emits 113% more heat than it receives, Saturn 139%, and Neptune 162%. Uranus only emits 12.5-15% more heat. This difference implies that Uranus may have a unique internal structure or evolutionary history.
These findings strengthen the scientific case for NASA’s planned Uranus Orbiter and Probe mission. This project, recognized as the highest priority new flagship mission by the 2023-2032 Planetary Science Decadal Survey, proposes a $4.2 billion mission with an orbiter and atmospheric probe, targeting a launch as early as 2031 and an arrival at Uranus around 2044.
