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    There Might Be More Than One Way to Make a Planet

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    Astronomers have found evidence of a process that supports an alternative, more rapid approach to planetary formation, more top down than bottom up.When it comes to making a planet, astronomers have long subscribed to what Cassandra Hall, an astronomer at the University of Georgia’s Center for Simulational Physics, refers to as the “bottom up” approach: The gas and dust swirling around a young star slowly clumps together over millions of years, and its gravity shapes it into a rounded object.But a discovery by Dr. Hall and her colleagues, published in the journal Nature this month, suggests that the picture might be more complex.In a star system 508 light-years from Earth, the researchers found conditions that support an alternative “top down” approach to planet formation, in which the fertile material circling a young star rapidly collapses into a planet. The mechanism, known as gravitational instability, could explain the existence of mysterious, massive worlds known to follow wide orbits around relatively young stars.“There’s never been real, hard evidence of it happening before,” Dr. Hall wrote in an email. “We found it!”The cosmic matter stirring around an infant star is ripe with planet-forming potential. The matter is known as a protoplanetary disk, and its rotation is generally driven by the gravity of its host star. But if that disk gets large enough, it can be influenced by its own gravity, causing the young star system to become unstable. Regions of higher density in the disk emerge in the form of spiral arms, similar to the shape of spinning clouds in a hurricane.“The star would be like the eye of the storm,” said Jess Speedie, a graduate student at the University of Victoria in Canada who led the study under the supervision of Ruobing Dong, an astrophysicist.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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      Voyager 1, After Major Malfunction, Is Back From the Brink, NASA Says

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      The farthest man-made object in space had been feared lost forever after a computer problem in November effectively rendered the 46-year-old probe useless.Several months after a grave computer problem seemed to spell the end for Voyager 1, which for nearly a half century had provided data on the outer planets and the far reaches of the solar system, NASA announced on Thursday that it had restored the spacecraft to working order.“The spacecraft has resumed gathering information about interstellar space,” NASA said in its announcement about Voyager 1, the farthest man-made object in space.Since the problem surfaced in November, engineers had been working to diagnose and resolve the issue, a tedious and lengthy process complicated by the fact that it takes almost two days to send and receive information from Voyager 1, which was the first man-made object ever to enter interstellar space and is currently more than 15 billion miles from Earth.The space community had been holding its breath since last year as the prospect of fixing the aging probe appeared as dire as ever.In February, Suzanne Dodd, the Voyager mission project manager, said the problem, which hindered Voyager 1’s ability to send coherent engineering and science data back to Earth, was “the most serious issue” the probe had faced since she began leading the mission in 2010.Voyager 1 and its twin probe, Voyager 2, were launched in 1977 on a mission to explore the outer planets. NASA capitalized on a rare alignment in the solar system that enabled the probes to visit the four of the outer planets — Jupiter, Saturn, Uranus and Neptune — by using the gravity of each to swing to the next.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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      Is This Black Hole the Hungriest and the Brightest?

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      Scientists debate whether this object is the brightest in the visible universe, as a new study suggests.Astronomers claimed on Monday that they had discovered what might be the hungriest, most luminous object in the visible universe — a supermassive black hole that was swallowing a star a day. That would be the mass equivalent of 370 suns a year disappearing down a cosmic gullet 11 billion years ago at the dawn of time.Burp indeed.In a paper published in Nature Astronomy, Christian Wolf of the Australian National University and his colleagues from Australia and Europe, called the object at the center of a newly discovered quasar known as J0529-4351 “the fastest growing black hole in the universe.”According to their estimates, this black hole tipped the scales as one of the most massive black holes ever found: 17 billion times as massive as the sun.But other astrophysicists cast doubt on the result, questioning the methods by which the mass and luminosity of the new quasar had been estimated. They said the calculations were too uncertain to be conclusive. “They may have the right value, but I don’t think other observers would be shocked if it turned out the true mass was somewhat less,” said Daniel Holz, a theoretical astrophysicist at the University of Chicago.“It does seem like an extreme object,” he said. But, he added, “I would be shocked if this turned out to be the most luminous quasar on the sky.”Jenny Greene, a professor of astrophysical sciences at Princeton University, called the result “cute.”We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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      The Doomsday Clock Keeps Ticking

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      Year
      Minutes to Midnight

      2023
      1.5

      2020
      1.67

      2018
      2

      2017
      2.5

      2015
      3

      2012
      5

      2010
      6

      2007
      5

      2002
      7

      1998
      9

      1995
      14

      1991
      17

      1990
      10

      1988
      6

      1984
      3

      1981
      4

      1980
      7

      1974
      9

      1972
      12

      1969
      10

      1968
      7

      1963
      12

      1960
      7

      1953
      2

      1949
      3

      1947
      7

      The Bomb and I go way back. In Seattle, where I grew up in the 1950s and ’60s, it was common wisdom that in the event of nuclear war, we were No. 2 on the target list because Seattle was the home of Boeing, maker of B-52 bombers and Minuteman missiles.In school we had various drills for various catastrophes, and we had to remember which was which. Earthquake? Run outside. The Bomb? Run inside, to an inner corridor that had no windows. In the summer, my high-school friends and I would disappear for a couple of weeks into the backcountry of the Cascades or the Olympic Mountains. I always wondered whether we would emerge to find the world in ashes.Once, in Santa Monica in 1971, I thought it was finally happening. I woke up on the floor, having been bounced out of my bed early one February morning. There was a huge roar. Everything was shaking. I crept to my one window and pulled aside the curtain, expecting to see a mushroom cloud rising over the Los Angeles basin. I saw nothing. When the radio came back, I learned there had been a deadly earthquake in the San Fernando Valley.I was sent on this trip down memory lane by the announcement on Jan. 23 from the Bulletin of the Atomic Scientists that it had decided not to change the setting of the Doomsday Clock, a metaphorical timepiece invented in 1947 as a way to dramatize the threat of nuclear Armageddon. The clock was originally designed with a 15-minute range, counting down to midnight — the stroke of doom — and the Bulletin’s members move it from time to time in response to current events, which now include threats like climate change and pandemics.In a burst of optimism in 1991, after the Soviet Union broke up and the first Strategic Arms Reduction Treaty was signed, the clock was turned way back to 17 minutes to midnight. “The Cold War is over,” the Bulletin’s editors wrote. “The 40-year-long East-West nuclear arms race has ended.”A year ago, after Russia invaded Ukraine and brandished the threat of using nuclear weapons, the clock was set to 90 seconds to midnight, the closest it has yet come to The End. The threat of nuclear weapons in Ukraine has diminished since then, but the clock remains poised at 90 seconds before zero.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More