Uranus isn’t as cold as we once imagined, says NASA

This zoomed-in image of Uranus, captured by the Near-Infrared Camera on NASA’s James Webb Space Telescope on Feb. 6, 2023, reveals stunning views of Uranus’ rings. (Image: NASA)

For decades, Uranus has puzzled scientists with its icy silence. It spins oddly, rolls on its side, and barely radiates any heat. Now, new research might finally offer answers—and it all started with a question scientists couldn’t shake.

Odd Planet with Chilling Secrets

Uranus is unlike any other planet in space. It tilts sideways, spinning like a barrel in orbit. Each pole gets 42 years of direct sunlight. Unlike most planets, it also spins in the wrong direction. And it has always appeared unnaturally cold from the inside.

NASA’s Voyager 2 passed Uranus in 1986. Its instruments showed almost no heat coming from within. Since then, experts believed the planet lacked internal warmth. This made it hard to fit Uranus into current planet formation theories.

These side-by-side images of Uranus, taken eight years apart by NASA’s Hubble Space Telescope, show seasonal changes in the planet’s reflectivity. The left image shows the planet seven years after its northern spring equinox when the Sun was shining just above its equator. The second photo, taken six years before the planet’s summer solstice, portrays a bright and large northern polar cap. (Image: NASA)

“For years, we thought Uranus had no heat,” said Amy Simon from NASA. “But explaining that never really made sense.” The mystery rested on just one Voyager data point. Simon added, “Everything relied on that single heat reading.”

Fresh Data Sparks a New Theory

In May, a group of scientists led by Oxford’s Patrick Irwin gave the cold case a second look. They used decades of telescope data with updated computer models. NASA’s Hubble and the Infrared Telescope Facility played key roles. The goal was to understand how Uranus reflects light and emits heat.

They found that Uranus is more reflective than previously believed. That small change had a big effect on their calculations. The planet gives off about 15% more energy than it gets from the Sun. That means Uranus does have some internal heat after all.

This number matches results from a different 2023 study. That study also suggested Uranus isn’t entirely frozen within. However, it still emits far less heat than Neptune, its closest planetary twin.

What It Means for the Solar System

The discovery rewrites part of Uranus’ story. Scientists can now explore new reasons for its low heat. A massive ancient collision may still be involved. But the new heat measurement shifts how they see the planet’s age and evolution.

“We need better tools to measure Uranus’ heat,” Simon added. “But this gives us a stronger place to begin.”

Understanding Uranus helps with more than just our solar system. It also helps scientists studying exoplanets. Most of these planets are Uranus-sized and share similar traits.

By solving Uranus’ strange riddle, researchers may learn more about how planets form and change across the universe.