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      Strange observations of galaxies challenge ideas about dark matter

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      Head-scratching observations of distant galaxies are challenging cosmologists’ dominant ideas about the universe, potentially leading to the implication that the strange substance called dark matter doesn’t exist.

      That’s one possible conclusion from a new study published June 20 in The Astrophysical Journal Letters. The finding “raises questions of an extraordinarily fundamental nature,” says Richard Brent Tully, an astronomer at the University of Hawaii at Manoa who was not involved in the work.

      Astronomers suspect dark matter exists because of the way stars and other visible material at a galaxy’s visible edge rotate. The rotation speeds of objects far from a galactic center are much higher than they should be given the amount of luminous stuff seen in telescopes. Under physicists’ current understanding of gravity, this implies that a massive reservoir of invisible matter must be tugging on those stars. More

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      A stellar explosion may add a temporary ‘new star’ to the night sky this summer

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      Keep your eyes on the night sky this summer, scanning for the constellation Corona Borealis, and if you are lucky, you may glimpse what appears to be a new star winking on in the dark.

      The brightening point of light will not be a new star, but a nova eruption about 3,000 light-years from Earth. There, a white dwarf star orbiting a red giant tears material from its larger companion. When enough mass collects on the white dwarf’s surface, the rising pressure and temperature will trigger a blast that can be seen from Earth with the naked eye — but for only a few days to a week. More

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      We may finally know the source of mysterious high-energy neutrinos

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      Supermassive black holes at the hearts of active galaxies may be churning out a lot of the universe’s high-energy neutrinos.

      Two teams using data from IceCube, the world’s premier neutrino observatory located in Antarctica, have independently identified a common type of these active galaxies, called Seyfert galaxies, as likely neutrino producers. These findings, reported in Physical Review Letters and arXiv.org, bolster some astronomers’ view that the cores of such active galaxies could churn out the majority of the cosmic neutrinos seen streaming across the universe. More

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      Venus might be as volcanically active as Earth

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      Present-day volcanism on Venus might be far more pervasive than previously believed.

      A new analysis of decades-old data from NASA’s Magellan spacecraft finds signs of fresh lava flows occurring on the Venusian surface between 1990 and 1992, researchers report May 27 in Nature Astronomy.

      “This definitely is another step in the path to understanding Venus as a living, breathing world,” says planetary scientist Paul Byrne of Washington University in St. Louis, who was not involved in the work. More

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      The universe may have a complex geometry — like a doughnut

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      The cosmos may have something in common with a doughnut.

      In addition to their fried, sugary goodness, doughnuts are known for their shape, or in mathematical terms, their topology. In a universe with an analogous, complex topology, you could travel across the cosmos and end up back where you started. Such a cosmos hasn’t yet been ruled out, physicists report in the April 26 Physical Review Letters. 

      On a shape with boring, or trivial topology, any closed path you draw can be shrunk down to a point. For example, consider traveling around Earth. If you were to go all the way around the equator, that’s a closed loop, but you could squish that down by shifting your trip up to the North Pole. But the surface of a doughnut has complex, or nontrivial, topology (SN: 10/4/16). A loop that encircles the doughnut’s hole, for example, can’t be shrunk down, because the hole limits how far you can squish it.  More

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      A weaker magnetic field may have paved the way for marine life to go big

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      Earth’s magnetic field protects life from harmful cosmic radiation. But sometime between about 590 million and 565 million years ago, that security blanket seems to have been much thinner — with far-reaching effects for the development of life on Earth, researchers suggest.

      A weaker magnetic field could account for the higher levels of oxygen recorded in the Earth’s atmosphere and oceans around that time — and for the ensuing proliferation of macroscopic marine animals, the team reports in the May 2 Communications Earth & Environment. More

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      Separating science fact from fiction in Netflix’s ‘3 Body Problem’ 

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      The orbits of a trio of stars can be so chaotic that it’s impossible to precisely calculate the stars’ future trajectories. That’s the real science behind the name of the hit Netflix show, 3 Body Problem. Much of the sci-fi show’s action hinges on a variety of other physics concepts. But in service of the plot, some of that science is taken to implausible — or even physically impossible — lengths.

      To get a handle on what’s real and what’s fiction, Science News spoke with cosmologist Jacques Delabrouille of CNRS in Paris and Lawrence Berkeley National Laboratory in California.  More

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      Pluto’s heart-shaped basin might not hide an ocean after all

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      Rather than a vast ocean, Pluto’s heart might be hiding a huge, heavy treasure.

      Computer simulations suggest that an object about 730 kilometers wide, slightly larger than the asteroid Vesta, could have slammed into the dwarf planet billions of years ago, forming the famous Sputnik Planitia and leaving behind a rocky remnant, researchers report April 15 in Nature Astronomy.

      Sputnik Planitia first appeared in images taken by NASA’s New Horizons spacecraft as it zipped past Pluto in 2015 (SN: 7/15/15). The heart-shaped feature, which has roughly the same area as the Democratic Republic of Congo, sits three to four kilometers below the rest of Pluto’s surface and is filled with frozen nitrogen. More