Astronomers have recently achieved a landmark feat: For the first time, they have captured an image of two black holes locked in orbit around each other . The discovery, led by Mauri Valtonen of the University of Turku in Finland, was published on October 9, 2025, in The Astrophysical Journal. The image reveals two supermassive black holes at the heart of the quasar OJ 287, some 5 billion light-years from Earth (in the constellation Cancer), engaged in a 12-year orbital dance.
This visual proof is a major step forward. While theories and indirect detections of binary black hole systems (such as the remarkable detection of two colliding black holes) have long existed, this is the first time we have clearly seen two such titanic objects orbiting each other. The result strengthens our understanding of how black holes grow and merge, and it could even provide new observational grounds for testing the predictions of general relativity. The image offers a dramatic confirmation of decades of theoretical work and observational hints, making it one of the most exciting breakthroughs in black hole astrophysics.
Black holes and binary black holes
A black hole is an object so dense and massive that nothing, not even light, can escape its gravitational grip after crossing the boundary known as the event horizon. Most black holes form when giant stars reach the end of their lives and collapse in on themselves. The truly enormous ones, called supermassive black holes, are a different story, though. These cosmic giants, millions or even billions of times the sun’s mass, are thought to form as galaxies merge, or when large amounts of gas and dust accumulate in a galactic core.
Under certain conditions, black holes may exist in pairs, known as binary black holes. Such systems form naturally when two galaxies merge, each carrying its own central black hole. Gravitational forces bring the two black holes together, causing them to orbit each other, and theoretically, they would gradually spiral inward, ultimately merging. Observational evidence for binary black holes has come primarily through the detection of gravitational waves, ripples in space-time predicted by the theory of general relativity.
Instruments such as LIGO and others have observed mergers of black hole pairs, confirming that such binary systems exist. Until now, however, no image has directly resolved two supermassive black holes in orbit. The new image, therefore, bridges the gap between the evidence provided by gravitational waves and visual confirmation. We now not only hear the spacetime ripples but also see the cosmic dance of two black holes.
Discovery of the binary black holes in OJ 287
The quasar OJ 287 was first noticed as a bright, variable object in photographic sky surveys in the late 19th century. Astronomers later found that its brightness displays changes in a roughly 12-year cycle. This pattern was first flagged by the Finnish astronomer Aimo Sillanpää in the early 1980s. He interpreted the patterns as a sign of two massive black holes interacting (possibly not unlike the two black holes found to be on a collision course with each other). The leading model proposed that a smaller black hole orbits a much larger counterpart, periodically punching through the larger’s accretion disc and producing a flare of light.
Over the decades, support for the binary hypothesis piled up. What was missing, until now, was a direct image resolving the two objects. Using a global array of telescopes, including the Russian satellite RadioAstron, which greatly extended the achievable resolution, Mauri Valtonen’s team from the University of Turku captured a radio wave image that shows two distinct components where the jets of the two black holes should be.
The team found that the larger of the two black holes has a mass of roughly 18 billion suns, and the smaller one is about 150 million stellar masses. The lighter companion produces a high-energy jet that spirals outward at nearly the speed of light. Therefore, the image not only visualizes the binary nature of OJ 287 but also confirms theoretical predictions of jet structure and orbital separation.
That said, the researchers caution that some uncertainties remain: The possibility that the two jets might be overlapping in the image cannot yet be ruled out. So until higher resolution observations are available, some doubt remains about whether we are seeing two distinct black holes or misinterpreting one jet structure. In other words, while the evidence is compelling and unprecedented, scientists remain vigilant in their claims.
