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Rubin Observatory Reveals Two Hidden Companions of the Milky Way
Confirmed
In Short: The Vera Rubin Observatory's ability to detect these hidden companions is attributed to its advanced technology and the vast amount of data it collects.
Researchers at Durham University predict that the Milky Way could be surrounded by up to 100 previously undetected satellite galaxies, based on ultra-high-resolution simulations and sophisticated modeling.
The Vera Rubin Observatory, using its powerful Simonyi Survey Telescope, detected a dwarf planet candidate 30 times over 20 nights between March and July 2026.
Matthew Holman, a senior astrophysicist from the Center for Astrophysics | Harvard & Smithsonian, led the discovery of the dwarf planet candidate.
Holman and his colleague Mario Jurić of the University of Washington confirmed the discovery after running billions of pieces of data collected by the Rubin Observatory through a search code.
The discovery of the dwarf planet candidate, named 2026 ED138, is significant as it lies farther away from Earth than Pluto, in the outer reaches of our solar system.
Astronomers also used the Rubin Observatory to detect a previously undetected satellite galaxy, suggesting that the Milky Way may be surrounded by far more satellite galaxies than previously thought.
The Vera Rubin Observatory's ability to detect these hidden companions is attributed to its advanced technology and the vast amount of data it collects.
The discovery of these hidden companions could potentially confirm major cosmological theories and reshape our understanding of the universe.
Astronomers have also used NASA’s Chandra X-ray Observatory and other telescopes to study a structure nicknamed the 'Treble Clef,' which resembles a musical symbol and is located directly behind the plane of the Milky Way.
The Treble Clef structure is the result of an ancient black hole outburst and the collision of two galaxy clusters, making it difficult to study due to the obstruction of stars, gas, and dust from the Milky Way.
What this adds
The Rubin Observatory's discoveries add to the growing body of evidence suggesting that the Milky Way has far more satellite galaxies than previously thought.
The detection of the dwarf planet candidate and the satellite galaxy demonstrates the potential of the Rubin Observatory to reveal new aspects of our cosmic neighborhood.
What's confirmed
- “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.” When Holman and his colleague Mario Jurić of the University of Washington went to double-check, they found 30 more observations of the object by Rubin that dated to between March and July 2026.
What's still developing
- According to their results, there could be 80 to 100 additional satellite galaxies orbiting near the Milky Way.
- But with the advent of powerful new instruments like the Rubin Observatory, scientists believe we’re finally approaching the ability to spot them, potentially confirming major cosmological theories and reshaping our view of the Universe.
- According to LCDM theory, many more Milky Way companion galaxies should exist than cosmological simulations have so far produced, or astronomers have been able to see.
- Published in Astronomy & Astrophysics on October 14, 2026, by a team led by Andrea Botteon of Italy's National Institute for Astrophysics (INAF), the study used observations from NASA's Chandra X-ray Observatory and other telescopes to piece together how the collision reshaped streams of energetic particles released by the black hole into this massive structure.
- The resemblance of the structure to a treble clef, however, is not naturally ordained but a mere coincidence, and according to NASA, is an example of "pareidolia", the phenomenon of humans seeing familiar shapes in random patterns.
- Astronomers using ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA) have observed the densest, most crowded regions at the centers of the Large and Small Magellanic Clouds, our Milky Way Galaxy’s closest dwarf companions, offering an unprecedented look at areas that have long resisted detailed study.
- Radio data shown in red from the LOw Frequency ARray (LOFAR), a large network of radio telescopes in Europe reveals the doppelganger of the musical notation.
- “ What is special about this star is that it’s orbiting Sagittarius A* on a very tight orbit, taking just 8.7 years to complete it, and is approaching the black hole at a mere 12 times the distance of Earth to the Sun. That is unprecedented,” says Felix Mang, PhD student at MPE and author of the study published today in Nature.
- The team used the VLTI, a facility at ESO’s Paranal Observatory in Chile and its GRAVITY instrument, now known as GRAVITY+ following an infrastructure upgrade. [2] The VLTI’s superpower lies in its ability to combine the light from four 8-metre telescopes to create a ‘virtual’ telescope with 15 times the spatial resolution of a single 8-metre telescope.
- The star, named S301, was detected with the European Southern Observatory’s Very Large Telescope Interferometer (ESO’s VLTI) and reaches speeds of 25 000 km/s as it travels around the four-million-Solar-mass black hole.
- The Roman telescope will offer astronomers an unprecedented view of planets across the Milky Way.
- In 2020, the space telescope was named after Nancy Grace Roman, NASA’s first Chief of Astronomy, who is often referred to as the “Mother of Hubble.” The mission's development really came together after the COVID pandemic.