Aug 20, 2025 10:03 PM
Did Earth once have a ring?
https://www.astronomy.com/science/did-ea...ve-a-ring/
KEY TAKEAWAYS: Geological evidence, including an Ordovician-era increase in earthquakes, tsunamis, meteorites, and crater formation, suggests a significant celestial event approximately 466 million years ago.
A study proposes that this event involved a large asteroid fragment passing within Earth's Roche limit, resulting in its disintegration and the subsequent formation of a temporary planetary ring composed of debris.
Analysis of Ordovician crater locations, after accounting for plate tectonics, indicates a concentration near the equator, supporting the hypothesis of a ring originating from equatorial debris.
The hypothesized ring's presence is linked to a period of significant global cooling and a subsequent biodiversity event, suggesting potential climatic and evolutionary impacts. (MORE - details)
The Milky Way's faintest satellite may not be what astronomers thought. 'These results solve a major mystery
https://www.space.com/astronomy/galaxies...trophysics
INTRO: A ghostly object orbiting the Milky Way has left astronomers questioning its composition: Is it a dark-matter-dominated dwarf galaxy or a star cluster bound by a hidden swarm of black holes?
Ursa Major III/Unions 1 (UMa3/U1), the faintest known satellite of our galaxy, orbits the Milky Way at a distance of more than 30,000 light-years. It is a compact stellar system that contains only 60 visible stars.
Ursa Major III was long thought to be a dark dwarf galaxy — a small galaxy with an unusually high mass-to-light ratio suggesting it's filled with dark matter — but new evidence suggests it is instead a compact star cluster whose gravity is held together by a core of black holes and neutron stars, according to a statement from the University of Bonn in Germany... (MORE - details)
https://www.astronomy.com/science/did-ea...ve-a-ring/
KEY TAKEAWAYS: Geological evidence, including an Ordovician-era increase in earthquakes, tsunamis, meteorites, and crater formation, suggests a significant celestial event approximately 466 million years ago.
A study proposes that this event involved a large asteroid fragment passing within Earth's Roche limit, resulting in its disintegration and the subsequent formation of a temporary planetary ring composed of debris.
Analysis of Ordovician crater locations, after accounting for plate tectonics, indicates a concentration near the equator, supporting the hypothesis of a ring originating from equatorial debris.
The hypothesized ring's presence is linked to a period of significant global cooling and a subsequent biodiversity event, suggesting potential climatic and evolutionary impacts. (MORE - details)
The Milky Way's faintest satellite may not be what astronomers thought. 'These results solve a major mystery
https://www.space.com/astronomy/galaxies...trophysics
INTRO: A ghostly object orbiting the Milky Way has left astronomers questioning its composition: Is it a dark-matter-dominated dwarf galaxy or a star cluster bound by a hidden swarm of black holes?
Ursa Major III/Unions 1 (UMa3/U1), the faintest known satellite of our galaxy, orbits the Milky Way at a distance of more than 30,000 light-years. It is a compact stellar system that contains only 60 visible stars.
Ursa Major III was long thought to be a dark dwarf galaxy — a small galaxy with an unusually high mass-to-light ratio suggesting it's filled with dark matter — but new evidence suggests it is instead a compact star cluster whose gravity is held together by a core of black holes and neutron stars, according to a statement from the University of Bonn in Germany... (MORE - details)