Uranus Warmer than Scientists Thought

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA Jet Propulsion Laboratory.

Video imagery:

·       Voyager 2 image of Uranus: NASA

·       Hubble observations of Uranus: NASA, ESA, Erich Karkoschka (LPL)

·       Hubble image of Uranus showing rings, 2005: NASA, ESA, Mark Showalter (SETI Institute), Lawrence A. Sromovsky (UW-Madison), Patrick M. Fry (UW-Madison), Heidi Hammel (SSI), Kathy Rages (SETI Institute)

·       Webb Space Telescope wide field image of Uranus: NASA, ESA, CSA, STScI; image processing: A. Pagan (STScI)

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Title: News From the Universe.

July 31, 2025. Uranus warmer than scientists thought.

In 1986, NASA's Voyager 2 spacecraft took the only close-up measurement of planet Uranus' emitted heat, and the low readings have puzzled scientists ever since.

According to Voyager's data, it seemed the giant planet had no internally generated heat at all, and the only energy it emitted was from reflected sunlight.

Researchers have now compiled decades of observations from various telescopes, including NASA's Hubble Space Telescope, to get to the bottom of the mystery.

To do this, they needed to estimate the total amount of light reflected from the planet at all angles. "You need to see the light that's scattered off to the sides, not just coming straight back at you," said scientist Amy Simon.

Computer models built with the data indicate that Uranus does generate some heat, releasing 15 percent more energy than it receives from the Sun.

The levels are still very low compared with neighboring planet Neptune, which emits more than twice the energy it receives from the Sun.

Scientists say the next step is investigating why Uranus has so much less internal heat. Is it older than other giant planets? Did it lose heat in a collision, which could have also "tipped" it on its side?

Though Uranus has been known to be a planet since the late 1700s, there is still a lot to discover about this unique member of our solar system.

This news was brought to you in part by the Goddard Space Flight Center in Greenbelt, MD.