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    Mars’ potato-shaped moons could be the remains of a shredded asteroid

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    Mars’ moons could be the remains of an ill-starred asteroid that got too close to the Red Planet.

    A shredded asteroid origin could help explain mysterious features of the small, odd-shaped moons, scientists suggest in the January issue of Icarus.

    Where most moons are big round orbs, Mars’ Phobos and Deimos are small lumpy potatoes.

    There are two main ideas for how the moons formed. One is that the moons actually were asteroids that were caught by Mars’s gravity. But that idea doesn’t explain the moons’ circular, stable orbits around Mars’ equator. More

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      Einstein’s gravity endures despite a dark energy puzzle 

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      Scientists could be wrong about dark energy. But they’re right about gravity, a new study suggests.

      Dark energy, the mysterious phenomenon that causes the expansion of the cosmos to accelerate, is widely thought to have had a constant density throughout the history of the universe. But dark energy may instead be waning, researchers from the Dark Energy Spectroscopic Instrument, or DESI, collaboration report November 19 in a batch of papers posted to the project’s website and arXiv.org. 

      The finding reaffirms an April report from the same team that had come to a similar conclusion (SN: 4/4/24). Simultaneously, the new analysis — a more thorough look at the same data used in the earlier report — confirms that the DESI data agree with general relativity, Albert Einstein’s theory of gravity, with no evidence for alternative, “modified gravity” theories.  More

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      A first look at rocks from the lunar farside create a volcanic mystery

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      The first samples from the farside of the moon contain signs of surprising volcanic activity near the lunar south pole.

      Two separate analyses of lunar rocks brought to Earth by China’s Chang’e-6 spacecraft show the rocks formed from cooling magma relatively recently, about 2.8 billion years ago, according to papers published November 15 in Science and Nature. The measurements may help solve the mystery of why the moon’s farside is so different from its nearside, but also raise new questions about the history of lunar volcanism. More

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      Uranus may have looked weird when NASA’s Voyager 2 flew by

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      Some of Uranus’ apparent oddities might be due to bad timing.

      In 1986, the Voyager 2 spacecraft flew past the planet, recording mysteries of its magnetic field. Turns out, Uranus may have just been in an unusual state. A solar wind event days before the flyby compressed the giant planet’s magnetosphere, researchers report November 11 in Nature Astronomy. That compression could explain several long-standing puzzles about Uranus and its moons, and could inform planning for future missions (SN: 4/20/22). More

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      A cosmic census triples the known number of black holes in dwarf galaxies

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      A colossal census of the cosmos has more than tripled the number of active black holes known to reside in miniature galaxies and found the biggest haul of middleweight black holes to date.

      The survey turned up about 2,500 dwarf galaxies with actively feeding black holes at their centers, up from about 500 known before, researchers report in a paper submitted October 31 to arXiv.org. The team also found nearly 300 new intermediate-mass black hole candidates, an increase from about 70 previous possible detections (SN: 9/2/20). More

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      A star winked out of sight. Could it be a ‘failed supernova’? 

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      Some massive stars may go out with a fizzle, not a bang.

      A star that winked out of view could be a “failed supernova,” a stellar explosion that petered out instead of fully detonating, a new study reports. If real, the failed supernova would mark the birth of a black hole.

      At the ends of their lives, massive stars explode in dazzling outbursts known as supernovas, kicked off when the star’s core collapses. But sometimes, scientists suspect, there’s not enough oomph for a full explosion, resulting in a star that switches off without fireworks.  More

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      A zombie star’s spiky filaments shed light on a 12th century supernova

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      Some 6,500 light-years from Earth lurks a zombie star cloaked in long tendrils of hot sulfur.

      Nobody knows how those tendrils formed. But astronomers now know where they’re going. New observations, reported in the Nov. 1 Astrophysical Journal Letters, capture the 3-D structure and motion of debris left in the wake of a supernova that was seen to detonate almost 900 years ago.

      “It’s a piece of the puzzle towards understanding this very bizarre [supernova] remnant,” says astronomer Tim Cunningham of the Harvard & Smithsonian Center for Astrophysics in Cambridge, Mass. More

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      Using AI, historians track how astronomy ideas spread in the 16th century

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      Historians working with an artificial intelligence assistant have begun tracking the spread of astronomical thinking across Europe in the early 1500s.

      The analysis contributes to challenging the “lone genius” idea of scientific revolutions. Instead, it shows that knowledge about the positions of the stars was widespread and used in a variety of disciplines, researchers report October 23 in Science Advances.

      “We can see here the first formation of a proto-international scientific community,” says computational historian Matteo Valleriani of the Max Planck Institute for the History of Science in Berlin. More

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      The cataclysmic origins of most of Earth’s meteorites have been found

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      Most of Earth’s meteorites can be linked to just a few collisions within the asteroid belt between Mars and Jupiter, two new studies report, including a particularly cataclysmic impact event around 470 million years ago.

      The upside to this discovery, published October 16 in Nature, is that it provides researchers with vital context: By knowing the return address of meteorites, scientists can more easily work out how and where the building blocks of planets came together to create the solar system we see today. The downside is that it may mean researchers have an extremely biased meteorite collection that can tell only a sliver of the story. More