Dying Stars Are Eating Their Planets — And Our Sun Will Too

Somewhere in the Milky Way right now, a dead star roughly the size of Earth is quietly dismembering a planet. It rips the world apart with tidal forces stronger than anything in our solar system, shreds it into a glowing disk of rubble, then pulls the pieces inward until they vaporize on its surface. Astronomers can read the chemical fingerprints of those destroyed worlds in the star's atmosphere — and what they have found is deeply unsettling for anyone living on a planet orbiting a middle-aged star.

Background

Stars like our Sun do not die quietly. After spending roughly 10 billion years fusing hydrogen into helium in their cores, they enter a final, violent chapter. The core contracts and heats up, forcing the outer layers to balloon outward into a red giant — a bloated, luminous sphere that can expand to more than 100 times the star's original diameter. In our Sun's case, that expansion will likely swallow Mercury and Venus outright, reaching a maximum radius of about 1.2 AU — 1.2 times Earth's current distance from the Sun.

The red giant phase does not last. After the helium fuel runs out, the outer envelope is expelled as a planetary nebula, and the exposed core collapses into a white dwarf: a dense, slowly cooling remnant roughly the mass of the Sun compressed into a sphere the size of Earth. Gravity at the surface is approximately 100,000 times Earth's surface gravity. A teaspoon of white dwarf material weighs around 15 tons.

That extreme gravity does something remarkable — and destructive. Any rocky body that ventures too close is torn apart by tidal forces, shredded into a disk of dust and gas, and slowly consumed. The white dwarf becomes a cosmic cannibal. And recent observations suggest this is not a rare aberration. It appears to be a standard feature of stellar death.

The First Time We Watched It Happen in Real Time

For decades, astronomers inferred planet-eating from chemical traces left in stellar atmospheres. Then in May 2020, the Zwicky Transient Facility at Caltech's Palomar Observatory caught something unprecedented: a star, designated ZTF SLRN-2020, that brightened by more than 100 times in just 10 days — then faded. Located about 12,000 light-years away in the constellation Aquila, it was the first direct, real-time observation of a star actively swallowing a planet.

The target was a Jupiter-sized gas giant orbiting closer to its star than Mercury orbits our Sun. Initial analysis suggested the aging star had expanded into a red giant and engulfed the planet through sheer physical growth. But follow-up observations from NASA's James Webb Space Telescope, published in The Astrophysical Journal in April 2025, told a more nuanced story.

Webb's MIRI instrument detected a ring of hot gas left by the event, along with an expanding cloud of cooler dust. NIRSpec identified carbon monoxide molecules in the debris. But the critical finding was orbital: the planet had not simply been overtaken by a growing star. Its orbit had been shrinking for millions of years — drawn inward by tidal interactions — until it finally crossed the point of no return. Lead researcher Ryan Lau noted that JWST is giving scientists "valuable insights about the final fates of planetary systems, possibly including our own."

The distinction matters enormously. If planets can spiral to their deaths even before their star goes full red giant, then planet engulfment may happen far more frequently — and earlier in a stellar system's life — than previously thought.

25 to 50 Percent of Dead Stars Are Actively Eating

The ZTF SLRN-2020 event was dramatic, but the broader evidence is even more striking. When astronomers survey white dwarfs in the solar neighborhood, they find that between 25 and 50 percent show signs of "pollution" — the presence of heavy metals in their atmospheres that cannot be there naturally.

White dwarfs are almost exclusively hydrogen and helium by composition. Elements like silicon, iron, magnesium, calcium, and oxygen should sink out of the atmosphere within days to millions of years — fast, on astronomical timescales. When those elements show up, it means planetary material is actively falling in right now, replenishing what gravity pulls down.

The white dwarf G238-44 gave astronomers an unusually complete picture. NASA's Hubble Space Telescope detected ten heavy elements in its atmosphere — including carbon, nitrogen, oxygen, magnesium, silicon, and iron — in proportions that matched "a nearly two-to-one mix of Mercury-like material and comet-like material," according to lead researcher Ted Johnson. This was the first confirmed case of a white dwarf simultaneously consuming both rocky inner-system bodies and icy outer-system bodies, the two distinct reservoirs of any mature planetary system. Johnson noted: "We have never seen both of these kinds of objects accreting onto a white dwarf at the same time."

In 2025, the white dwarf LSPM J0207+3331 — 145 light-years from Earth — added to this picture. Spectroscopic data from the W. M. Keck Observatory's HIRES instrument found 13 chemical elements in its hydrogen-rich atmosphere, including sodium, aluminum, titanium, chromium, cobalt, copper, and strontium. These came from a rocky body at least 120 miles (roughly 193 kilometers) wide that had been torn apart by tidal forces. At 3 billion years old, LSPM J0207+3331 hosts what astronomers describe as "the oldest and most metal-rich debris disk ever observed around a hydrogen-rich white dwarf" — suggesting the planetary cannibalism can continue for billions of years after the star's death.

In 2024, a team at the University of Texas at Austin used AI-based manifold learning to identify hundreds of previously undetected polluted white dwarfs in the Milky Way — achieving a 99 percent success rate in classification and dramatically expanding the known population of planet-eating stars. The scope of this process across the galaxy is almost certainly enormous.

How a Star Tears a Planet Apart

The actual mechanics of planetary destruction are as violent as they sound. A rocky body — asteroid, moon, or full planet — can be scattered onto a close approach with the white dwarf by gravitational perturbations from surviving outer planets, similar to how Jupiter periodically flings comets into the inner solar system. As the body crosses the Roche limit — the critical distance below which tidal forces exceed the body's self-gravity — it begins to disintegrate.

The debris spreads into a flattened disk around the white dwarf, glowing in infrared from the heat generated by particle collisions. Some of that material sublimes directly into gas; the rest spirals inward, guided by the Poynting-Robertson effect and gas drag, until it reaches the stellar surface and is absorbed. The entire process, from disruption to accretion, can unfold over millions of years.

What emerges in the white dwarf's spectrum is essentially a chemical autopsy of an entire world. Astronomers can measure what the destroyed body was made of — the ratio of silicon to iron tells them whether it was crust, mantle, or core material; the presence of oxygen in excess of what the metals need tells them the planet held water. One extraordinary detection in 2025 found a debris disk with oxygen content consistent with roughly 64 percent water ice by mass — the remnants of something like a frozen ocean world, consumed billions of years after its star's death.

Why It Matters

The immediate scientific value of polluted white dwarfs is obvious: they are the only way astronomers can directly measure the bulk composition of rocky planets in other solar systems. Every other method — transit depth, radial velocity wobble, atmospheric spectroscopy — tells you about a planet's size, mass, or surface. White dwarf spectroscopy tells you what is inside. It is exoplanetary geology by autopsy.

But the long-range implication is harder to sit with. The same process observed in a quarter to half of all white dwarfs in the solar neighborhood will, in approximately 5 billion years, be applied to our own solar system. The Sun will expand into a red giant, very likely consuming Mercury and Venus directly through engulfment. Earth sits in the uncertain zone: as the Sun sheds roughly half its mass, Earth's orbit may drift outward to 1.5 AU — possibly beyond the expanding stellar surface. Or tidal drag from the Sun's outer atmosphere may pull Earth's orbit inward until it meets the same fate as the closer planets.

Either way, the asteroid belt, the outer solar system, and whatever fragmented remains of the terrestrial planets survive the red giant phase will eventually be scattered by the gravitational dynamics of a reconfigured system. Jupiter, still massive even after billions more years, will continue tossing rocky debris inward. The white dwarf remnant of our Sun — approximately 0.54 solar masses compressed into an Earth-sized sphere — will feed on whatever falls its way, for billions of years after the solar system as we know it no longer exists.

We are already building the machines capable of reading that future. JWST can detect the chemical signatures of planetary debris in stellar spectra. Upcoming surveys will identify thousands more polluted white dwarfs. What those observations are building, one element at a time, is a complete theory of how solar systems die — and what they were made of when they lived.

Frequently Asked Questions

Will the Sun really eat Earth?

Earth's fate depends on competing forces during the Sun's red giant phase, roughly 5 billion years from now. As the Sun loses mass, Earth's orbit may expand outward beyond the expanding stellar envelope. However, tidal drag from the Sun's outer atmosphere could reduce Earth's orbit instead. Mercury and Venus will almost certainly be engulfed outright; Earth remains genuinely uncertain.

What is a polluted white dwarf?

A polluted white dwarf is a stellar remnant whose atmosphere contains heavy elements — silicon, iron, calcium, magnesium, and others — that should have sunk out of the hydrogen-helium atmosphere relatively quickly. Their presence indicates the star is actively accreting planetary material right now. Between 25 and 50 percent of white dwarfs in the solar neighborhood are polluted, making this process remarkably common.

How do scientists know what a destroyed planet was made of?

The chemical composition of the accreted material shows up in the white dwarf's spectrum. By measuring the relative abundances of elements like iron, silicon, magnesium, oxygen, and carbon, astronomers can reconstruct whether the destroyed body was rocky, icy, metallic, or some mixture — in the same way a geologist reads a rock sample. White dwarf spectroscopy is currently the most direct method available for measuring the interior bulk composition of exoplanetary bodies.

Did JWST observe a planet being swallowed?

JWST followed up on ZTF SLRN-2020, the first real-time planetary engulfment event recorded, initially detected in 2020 by the Zwicky Transient Facility. JWST's 2025 observations revealed that the Jupiter-sized planet's orbit had been shrinking for millions of years before the final engulfment — a finding that suggests orbital decay plays a larger role in planetary death than the star simply growing outward.

How long does a white dwarf feed on its planets?

The feeding process can continue for billions of years after a star's death. LSPM J0207+3331, a white dwarf 3 billion years old, is still actively accreting planetary debris — making it the oldest confirmed example of ongoing planetary consumption. As long as surviving outer planets can gravitationally scatter rocky bodies inward, the white dwarf will continue to feed.

The Takeaway

The universe is far more efficient at dismantling worlds than it is at building them. A planetary system that took 100 million years to assemble can be fed, piece by piece, into its dying star over the following billions. What JWST and Hubble are now uncovering is not a rare catastrophe but a predictable final chapter written into the physics of every solar system orbiting a Sun-like star. The question scientists are now turning to is not whether our solar system faces this fate — but whether anything readable will survive in the Sun's white dwarf atmosphere long enough for some future civilization to decode what Earth was made of.

Sources

• NASA Webb's Autopsy of Planet Swallowed by Star Yields Surprise — NASA JPL, 2025
• Dead Star Caught Ripping Up Planetary System — NASA Science / Hubble, 2022
• Aging White Dwarf Still Consuming Its Planetary System — Space Telescope Science Institute, 2025
• Astronomers Use AI to Find Elusive Stars 'Gobbling Up' Planets — University of Texas at Austin, 2024
• Chapter 6: Aging Into Gianthood — NASA Science, 2024
• Star Eats Planet, Brightens Dramatically — Caltech, 2023