Scientists have discovered that Saturn’s icy moon Enceladus is warmer than they thought — and that its hidden ocean may have remained liquid for billions of years, creating conditions where life could possibly exist.
A new study led by researchers from the University of Oxford, the Southwest Research Institute, and the Planetary Science Institute has found strong evidence of heat flow at Enceladus’s north pole.
Until now, scientists believed most of the moon’s heat came only from its south pole, where plumes of water vapor shoot out into space.
This new finding, published in Science Advances, shows that heat is also escaping from the north — a sign that Enceladus’s ocean is globally active and could remain stable over time.
“Understanding how much heat Enceladus is losing is key to knowing if it can support life,” said Dr. Carly Howett, a co-author of the study. “It’s exciting that this result supports Enceladus’s long-term sustainability — one of the ingredients needed for life.”
Enceladus, only about 500 kilometers across, has fascinated scientists since NASA’s Cassini spacecraft discovered geysers spraying icy water from its south pole.
Beneath its thick shell of ice lies a global ocean mixed with salts, heat, and organic molecules — all essential ingredients for life.
But for that ocean to stay habitable, the moon must keep its energy in balance: enough internal heating to prevent freezing, but not so much that it becomes unstable.
That energy comes from tidal forces. As Saturn’s gravity pulls and stretches Enceladus during its orbit, the friction inside the moon produces heat. The new study shows that this process is happening across the entire moon, not just at the poles.
The research team analyzed thermal data collected by Cassini’s infrared spectrometer during Enceladus’s long winter and summer.
They found that the north pole was about 7 Kelvin (around 7°C) warmer than expected. The only explanation, they say, is heat escaping from the subsurface ocean below the ice.
The measured heat flow was about 46 milliwatts per square meter — two-thirds the rate of heat leaving Earth’s continents. Spread across Enceladus, that’s roughly 35 gigawatts of power, equivalent to the energy from 10,500 large wind turbines or more than 60 million solar panels.
When combined with the heat escaping from the south pole, the total reaches around 54 gigawatts, matching the energy expected from tidal heating. This balance means Enceladus’s ocean is likely stable over long timescales.
The researchers also used thermal data to estimate ice thickness — finding that it’s about 20 to 23 kilometers deep at the north pole and around 25 to 28 kilometers on average globally, slightly thicker than earlier estimates.
Dr. Georgina Miles, the study’s lead author, said that the discovery highlights the importance of long-term space missions. “Cassini’s data continue to reveal new secrets years after the mission ended,” she said. “If we want to find life elsewhere, we need patient, detailed exploration of these ocean worlds.”
With liquid water, warmth, and essential chemicals, Enceladus remains one of the most promising places in the solar system to search for alien life — perhaps waiting quietly beneath its frozen surface.
