Amateur Astronomers Discover Moon Orbiting Asteroid Queen’s

Observations by amateur astronomers reveal a moon orbiting asteroid 5457 Queen’s, adding to the growing list of known asteroid moons.

Amateur astronomers have made a groundbreaking discovery, capturing evidence of a moon orbiting the asteroid 5457 Queen’s. The observations, made by Czech astronomer Jan Mánek and Greek astronomer Serge Dramonis, have provided valuable insights into the nature of asteroids and their satellites. This finding adds to the growing list of known asteroid moons and highlights the crucial role that amateur astronomers play in expanding our knowledge of the solar system.

Unveiling the Unexpected: A Double Eclipse

During an occultation event on September 4, 2023, Jan Mánek and his colleagues were prepared to witness the moment when asteroid Queen’s passed in front of a 12.5-magnitude star in the constellation Pisces. To their surprise, they not only observed the expected occultation but also a second eclipse that occurred just 0.87 seconds later. This unexpected event hinted at the presence of a moon trailing behind Queen’s.

Serge Dramonis confirmed Mánek’s observation when he witnessed a similar double eclipse caused by the same asteroid on September 20th. The consistency between the two observations provided strong evidence that the asteroid Queen’s indeed had a moon.

Analyzing the Data: Revealing the Moon’s Characteristics

Christian Weber, an expert in occultation timing, analyzed the data collected by Mánek and Dramonis. His analysis revealed that the satellite orbiting asteroid Queen’s measures less than 2.8 kilometers (1.7 miles) in diameter. In comparison, Queen’s itself has dimensions of approximately 25×16 km. This discovery further enriches our understanding of the diverse characteristics of asteroids and their accompanying moons.

Joining the Ranks: A Rare Find

The moon orbiting asteroid Queen’s is only the second main-belt asteroid moon to be discovered and confirmed using the occultation method. The first, belonging to asteroid 4227 Arecibo, was discovered by Australians David Gault and Peter Nosworthy in 2021. While there have been other asteroid moons discovered through occultations, such as 523764 2014 WC 510 and 10199 Chariklo, these findings are still awaiting independent confirmation.

Building on Past Discoveries: A Brief History of Asteroid Moons

The discovery of asteroid moons has been an ongoing endeavor. In 1993, the Galileo spacecraft captured the first image of a satellite, Dactyl, orbiting asteroid 243 Ida. Ground-based observations at the La Silla Observatory in Chile led to the discovery of the first binary asteroid system in 1997, involving asteroid 3671 Dyonisus. Subsequent discoveries, such as the two moons of asteroid 87 Sylvia, named Romulus and Remus, have expanded our knowledge of multiple asteroid systems.

Advancements in Occultations: Unlocking the Secrets of the Solar System

Technological advancements have significantly improved the ability to predict and observe asteroid occultations. In 1978, James McMahon observed the asteroid 532 Herculina occult a star, reporting multiple “extinctions” that he attributed to satellites or rings. However, subsequent investigations by the Hubble Space Telescope found no evidence of such structures. Today, with the availability of fast and sensitive video cameras, precise GPS timing, and reliable occultation predictions from the Gaia mission, occultations have become an essential tool for exploring the solar system.


The discovery of a moon orbiting asteroid Queen’s by amateur astronomers highlights the invaluable contributions made by enthusiasts in expanding our understanding of the solar system. The observations made by Jan Mánek and Serge Dramonis provide a glimpse into the complex nature of asteroids and their accompanying moons. With advancements in technology and increased interest in occultations, we can expect many more exciting discoveries in the future, shedding light on the mysteries of our celestial neighborhood.






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