Chinese astronomers have directly measured the mass of a free-floating object for the first time, confirming it as a Saturn-sized planet using a novel space-ground observation technique.
BEIJING: Chinese scientists have confirmed the identity of a mysterious free-floating object as a planet with a mass comparable to Saturn.
This marks the first successful direct mass measurement of such a celestial body, which drifts alone through interstellar space without orbiting any star.
The key research was led by a team from Peking University’s Department of Astronomy and published in the journal Science.
Team head Dong Subo explained that these objects are detected through microlensing events.
“When a free-floating object passes in front of a background star, its gravity bends the starlight like a lens, causing the star to brighten temporarily,” he said.
While ground-based telescopes have detected about ten such objects over the past decade, accurately measuring their mass had remained impossible until now.
The breakthrough came by combining observations from Earth and a distant spacecraft with a time difference.
This method broke the “mass-distance degeneracy,” allowing the team to separately determine the object’s mass and distance.
Dong likened the technique to “observing the same scene with ‘eyes’ that are extremely far apart.”
A reviewer for Science said the achievement highlights the significance of space-ground coordinated observations.
It also provides an important reference for upcoming projects like NASA’s Roman Space Telescope.
China’s independently developed China Space Station Telescope, planned for launch, will also support such observations in the future.
