Some planets, like our own planet Earth, bask in the warm light of their stars. But others wander through eternal darkness, orbit the remains of dead suns, or slowly dissolve into clouds of dust.
These eerie worlds are sometimes called “ghost planets,” although astronomers don’t use that term as an official scientific classification. Instead, it offers a fitting Halloween-inspired way to explore several very real cosmic phenomena, from free-floating planets to worlds that have survived the deaths of their stars.
Grab your telescope, and perhaps a flashlight: we’re venturing into the darkest corners of the Universe.
Artist's conception of a Jupiter-size rogue planet. Image: NASA/JPL-Caltech.
1. Rogue Planets Wandering Alone
Imagine a planet drifting through space with no sunrise, no seasons, and no star to orbit. These lonely objects are known as rogue, or free-floating, planets.
Some rogue planets may have formed on their own, but others probably began as ordinary members of their solar systems. Violent gravitational encounters with neighboring planets or stars may have flung them from their original homes, causing them to wander the galaxy alone.
Because rogue planets reflect little to no starlight, they can be extremely difficult to spot. Astronomers often find them through gravitational microlensing. When a rogue planet passes in front of a distant star, its gravity bends and briefly magnifies the star’s light.
Being hard to find doesn't necessarily mean these planets are small. In 2026, researchers reported a likely free-floating planet about 70 times the size of Earth. Observations from Earth and the Gaia spacecraft helped scientists measure its mass more precisely, although they cannot completely rule out the possibility that it follows a very distant orbit around an unseen star. And while these castaway worlds are drifting alone, they may not be entirely unique. Scientists estimate that there are trillions of these rogue planets in our Galaxy, about 20 times more than there are stars. Recent research suggested that NASA's new Nancy Grace Roman Space Telescope, expected to launch in 2027, could uncover up to 400 more rogue planets the size of Earth.
Artist's depiction of planets oribiting the pulsar PSR B1257+12. Image: NASA/JPL-Caltech/R. Hurt (SSC).
2. Planets Orbiting a Dead Star
Some ghostly planets technically still have a star, but only the remains of one.
The planets Poltergeist and Phobetor orbit PSR B1257+12, a pulsar created from the collapsed core of a massive star. Pulsars are rapidly spinning neutron stars that sweep beams of radiation through space with remarkable regularity, somewhat like extremely intense cosmic lighthouses.
Astronomers discovered these planets by detecting tiny variations in the arrival times of the pulsar’s radio signals. Their gravitational pull causes the pulsar to wobble slightly, disrupting the pattern of its otherwise reliable pulses.
Announced in 1992, the planets orbiting PSR B1257+12 became the first confirmed worlds discovered outside our solar system. You read that right: the first known exoplanets were found orbiting the remains of a dead star. Talk about a dramatic reveal.
The system also contains a much smaller planet commonly called Draugr, named after an undead creature from Norse mythology. Scientists are still investigating whether these worlds somehow survived the star’s violent transformation or formed later from a disk of leftover debris.
The Jupiter-sized planet WD 1856 b (right) orbits the white dwarf star, WD 1856+534 (left). Image: NASA’s Goddard Space Flight Center.
3. The “Zombie Planet”
Approximately 80 light-years away, a Jupiter-sized planet known as WD 1856 b circles a white dwarf star called WD 1856+534.
A white dwarf star is the dense, lingering core left behind after a Sun-like star runs out of fuel and loses its outer layers. Before reaching that stage, the star expands into a red giant, potentially engulfing nearby planets.
That makes WD 1856 b’s current location especially puzzling. The planet completes one orbit every 34 hours and sits so close to the white dwarf that it should not have survived the star’s red-giant phase. Yet there it is, refusing to rest in peace.
According to NASA, the leading explanation is that WD 1856 b originally orbited much farther away, safely beyond the star’s reach. Gravity from other objects may have pushed it inward after the white dwarf formed. And while it didn’t literally rise from the dead, “zombie planet” feels like an appropriate nickname for such an unlikely survivor.
Artist's concept of Kepler-1520b disintegrating as it orbits its host star. Image: NASA/JPL-Caltech.
4. Worlds Turning to Dust
Not every planet escapes its star’s fiery wrath. Some may be slowly vaporized by it.
Kepler-1520b and K2-22b orbit dangerously close to their stars, completing an entire year in less than one Earth day. The heat may be intense enough to vaporize material on their rocky surfaces. As that material escapes and cools, it can condense into mineral dust, forming a comet-like tail.
The amount of dust varies, so these planets don’t create the clean, regular dips in starlight typical of planetary transits. Instead, their signals vary as shifting clouds of debris pass in front of their stars.
Kepler-1520b may be shedding its rocky material into space over millions of years. It is less a sudden vanishing act than an extremely long, drawn-out disappearance. Meanwhile, K2-22b completes an orbit in approximately nine hours and may have dust extending ahead of it as well as behind it.
While these planets are certainly doomed, their end is nowhere in sight—this process, known as “catastrophic evaporation,” can take tens to hundreds of billions of years. There is one bright side to these tragic planets, however: as they disintegrate, they may help scientists learn more about the composition of similar rocky planets.
Artist's impression of the star Fomalhaut and the disproven planet, Fomalhaut b. Image: ESA/NASA, M. Kornmesser.
5. The Planet That Wasn’t There
Our final ghost planet pulled off the ultimate disappearing act. Announced in 2008, Fomalhaut b appeared as a bright point moving near a dusty ring surrounding the star Fomalhaut, about 25 light-years from Earth. Astronomers initially celebrated it as a rare direct image of an exoplanet.
But something did not add up. The object produced little of the infrared heat expected from a planet. Over time, it became more diffuse, faded, and eventually disappeared from view.
The leading explanation is that Fomalhaut b was never a planet. The Hubble Space Telescope may instead have witnessed the aftermath of a collision between two large icy bodies. The impact created an expanding cloud of dust, which reflected the star’s light before gradually dispersing.
The object itself was real, but its identity was mistaken. NASA’s Exoplanet Archive now lists Fomalhaut b as a false positive rather than a confirmed planet.
Ghosts or Not, Outer Space Is Strange Enough
Rogue planets wander without stars. Other worlds circle stellar remains, survive the deaths of their suns, or burn up and disintegrate, leaving behind trails of their own rocky remains. One famous “planet” turned out to be a fading cloud of cosmic debris.
Names such as ghost planet, zombie planet, and poltergeist may be playful, but the science behind them reveals how surprising planetary systems can be. Worlds can be ejected, transformed, destroyed, and even mistaken for something they are not.
These planets remind us that, ghost stories or not, the Universe still holds many mysteries—and plenty of strange surprises we have yet to discover.
Want to discover more incredible stories from outer space? Visit the Museum’s Nathan and Fannye Shafran Planetarium, where our Astronomers will lead you through live, interactive tours of the stars. Explore current planetarium shows.
