Astronomers Discover Disintegrating Planet with a Massive Dust Trail

In an unexpected find, astronomers have detected a distant exoplanet with a debris stream resembling a comet—extending an incredible 5.5 million miles through the cosmos.

This peculiar planet, referred to as BD+05 4868 Ab, is located roughly 140 light-years away from Earth within the constellation Pegasus. It seems to be disintegrating rapidly due to the strong radiation emitted by its nearby star. The intense heat is causing the planet’s rocky exterior to vaporize, resulting in a long, dusty trail behind it.

Scientists report that this rocky planet is losing material at an alarming speed—shedding an amount comparable to the mass of Mount Everest with every orbit. If this trend persists, the planet could completely disappear within 1 to 2 million years.

The revelation came from a group of researchers at MIT utilizing NASA’s Transiting Exoplanet Survey Satellite (TESS). TESS is designed to find new planets by detecting dips in starlight when planets transit in front of their stars. The results were recently published in the Astrophysical Journal Letters.

“We weren’t looking for this type of planet,” remarked lead author Marc Hon in a statement. “I happened to notice a signal that seemed very unusual.”

Only three other exoplanets with comet-like tails have been discovered to date—all over ten years ago. However, BD+05 4868 Ab is notable for the remarkable length of its tail and the brightness of its host star, which facilitates observation with advanced telescopes. The research team plans to utilize the James Webb Space Telescope this summer to inspect the tail’s composition and identify the minerals making up the planet.

One fascinating detail already revealed is that the dust particles in the tail are as large as grains of sand. Without this substantial tail, scientists might have never recognized that the planet was disintegrating. The tail partially obstructs the star’s light during transits, producing irregular dimming patterns that alerted researchers to the planet’s strange behavior.

“We were fortunate to catch it at this moment—just as it’s fading away,” stated co-author Avi Shporer. “It’s like witnessing its last moments.”

BD+05 4868 Ab is approximately the size of Mercury and completes an orbit around its star every 30.5 hours—meaning its year is only slightly longer than an Earth day. The planet orbits about 20 times closer to its star than Mercury does to our sun. At such closeness, surface temperatures could soar to 3,000 degrees Fahrenheit, likely transforming the surface into a sea of molten rock.

Over billions of years, the star’s powerful radiation has gradually eroded the planet’s mass. Its small size and insufficient gravity hinder its ability to hold onto its material, accelerating its extinction.

Currently, the team is sifting through more TESS data in hopes of discovering other planets with similar dust trails. These rare treasures could provide a unique chance to investigate the internal composition of rocky worlds—yielding valuable insights into the variety of Earth-like planets throughout the galaxy.

“Sometimes, finding one thing unlocks the potential for many more,” Shporer added.