- 3276 - COMET - Bernardinelli-Bernstein”. This comet was the largest such icy body identified to date, perhaps more than 100 miles across. It sprouted a tail when it was remarkably far from the sun.
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--------------------- 3276 - COMET - Bernardinelli-Bernstein”.
- Trans-Neptunian objects (TNOs) are hunks of rock that circle the sun but remain out beyond Neptune's orbit. That's about 30 times the Earth's average distance from the sun, which is about 93 million miles and which scientists call an astronomical unit, AU. But most TNOs never stray farther from the sun than a few hundred AUs.
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- The researchers spotted Comet Bernardinelli-Bernstein in data called the “Dark Energy Survey (DES)”, which ran on a telescope at the Cerro Tololo Inter-American Observatory in Chile from 2013 to 2019.
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- The Dark Energy Survey was a survey designed to help scientists understand “dark energy“, a mysterious substance that scientists have not yet seen directly but is believed to make up 68% of the universe and warps our view of other galaxies.
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-The DES project captured more than 80,000 images of the sky, revisiting specific patches about every two weeks. In each image are tens of thousands of cosmic objects of all shapes and sizes.
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- A supercomputer software was designed in a way to spot TNOs within the Dark Energy Survey images. Using the time and location of each image to stack up solar system views, the researchers set the algorithm to identify when at least seven different images lined up to show a speck moving according to the laws that govern the movement of solar system objects.
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- Based on the object's brightness and distance, the scientists initially estimated that this comet's nucleus, the icy rock at its core, was 60 to 120 miles wide.
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- Since scientists know of plenty of TNOs of that size, but as far as comets go, that size estimate is truly massive. Among the comets scientists have studied in detail, only two are in the same class: Comet Hale-Bopp, which made a close approach to Earth in 1997, and Comet C/2002 VQ94 (LINEAR), which came no deeper into the solar system than Jupiter's orbit.
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- Large comets are rare because they vaporize ice that makes them so spectacular to see robs them of their being. Every pass by the sun leaves the comet a little bit smaller than before.
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- The history of our young solar system sported a ring of small, icy rubble surrounding the massive planets. But when the planets migrated through the solar system, their huge gravity kicked the frozen rubble around. Some flew out into interstellar space; some ended up in what scientists call the “Kuiper Belt“, where Pluto orbits.
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- Some ended up in the much more distant “Oort Cloud” where comets like Bernardinelli-Bernstein lurk. From there, as tides flow through the Milky Way and neighboring stars pass our solar system, gravity occasionally kicks a snowball inward.
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- There are plenty of Kuiper Belt objects that look like the new comet. Scientists turned their telescopes to the object's modern location and combed through archival data to rescue sightings that were missed in original analysis. And in those objects, it was clear that Comet Bernardinelli-Bernstein wasn't fully frozen and had already woken up a little by the time it first appeared in scientists' images.
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- Comets grow their distinctive fuzzy comas when their ices warm up enough to vaporize away into a gaseous cloud surrounding the nucleus. The phenomena obscures the nucleus and brightens the comet, which means that if Comet Bernardinelli-Bernstein was active in even the earliest sightings, scientists had overestimated its size.
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- Observations of Comet Bernardinelli-Bernstein gathered by an outpost of the Las Cumbres Observatory in South Africa in June, 2021, show activity on the comet despite its huge distance from the sun.
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- Calculating the size of an active comet is much more complicated than measuring a bare nucleus. Scientists have only spotted a handful of comets active so far away from the sun, where temperatures are still too cold for water ice to turn to vapor, a typical type of comet activity.
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- Given a 2021 discovery and a 2031 close approach to the sun, plus old observations from as early as 2010, scientists have a decades-long look at the object that's rare for this class of comet that makes such long journeys.
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- September 15, 2021 COMET - Bernardinelli-Bernstein”. 3276
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