Exploring Alien Oceans and Earth-Size Stars: An Astronomer’s Bold Case for Life Around White Dwarfs

The sun will eventually run out of hydrogen and die. This isn’t just doom and gloom; it could spark a whole new phase for our solar system. When stars like the sun die, they expand into what’s called a Red Giant. This phase is marked by the star growing larger and turning red. As it can no longer hold onto its outer layers because of weakened gravity, a significant chunk of its mass escapes into space, leaving behind a white dwarf.

I’m an astronomy professor at the University of Wisconsin-Madison. My team made an exciting discovery in 2020: the first intact planet found orbiting a white dwarf. This opened up intriguing questions about the potential for life on planets circling these dense remnants.

To look for signs of life on distant worlds, scientists often wait for a planet to pass in front of its star. When this happens, they can analyze the starlight filtering through the planet’s atmosphere to find out what gases are present. Recent research indicates that this method could work with planets around white dwarfs too. If an orbiting planet has life’s telltale gases, the James Webb Space Telescope might just spot them.

In June 2025, I published a paper addressing a fascinating question: Can oceans, crucial for life, survive on planets near dead stars? The answer isn’t straightforward. One challenge is how close these planets are to their stars. White dwarfs are relatively faint, so their habitable zones—where conditions might allow for liquid water—are much closer than those around our sun. These zones could be 10 to 100 times closer, meaning any potential planets are at risk from tidal heating and other challenges.

Being so close can lead to tidal heating, similar to what happens on Jupiter’s moon, Io, which experiences intense volcanic activity. This might mean that planets close to white dwarfs could find it difficult to keep liquid water, crucial for life.

As stars transition into white dwarfs during their Red Giant phase, they expand significantly, engulfing nearby planets. For a planet to survive this process, it often needs to start far away and migrate inward afterward. While simulations show this is possible, the migration process can generate heat that might evaporate the planet’s water—like how Io’s extreme heat prevents water from existing on its surface.

Despite these challenges, researchers are optimistic about the potential for life around white dwarfs. So far, no Earth-like exoplanets around white dwarfs have been confirmed, largely due to the difficulty of spotting them. Traditional methods, like the transit technique, are less effective because these stars are much smaller than typical stars hosting planets.

However, scientists are creating new ways to detect and study these elusive planets, especially using advanced telescopes like the Webb telescope. If we find life-sustaining planets around white dwarfs, it could revolutionize our understanding of where life can exist—even long after stars have died.

The search continues, but the universe’s potential surprises keep the excitement alive. To learn more about the challenges and possibilities of life around these fascinating stars, check resources from reputable scientific sites, such as NASA’s Hubble.

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