NASA’s Hubble Space Telescope has determined the size of the largest icy comet nucleus ever seen by astronomers. The estimated diameter is approximately 80 miles across.
The nucleus is about 50 times larger than found at the heart of most known comets. Its mass is estimated to be a staggering 500 trillion tons, a hundred thousand times greater than the mass of a typical comet found much closer to the Sun.
The comet, C/2014 UN271 (Bernardinelli-Bernstein) is barreling this way at 22,000 miles per hour from the edge of the solar system. It will never get closer than 1 billion miles away from the Sun, which is slightly farther than the distance of the planet Saturn. And that won’t be until the year 2031.
The comet has been falling toward the Sun for well over 1 million years. It is coming from the hypothesized nesting ground of trillions of comets, called the Oort Cloud. The diffuse cloud is thought to have an inner edge at 2,000 to 5,000 times the distance between the Sun and the Earth. Its outer edge might extend at least a quarter of the way out to the distance of the nearest stars to our Sun, the Alpha Centauri system.
Comet Bernardinelli-Bernstein follows a 3-million-year-long elliptical orbit, taking it as far from the Sun as roughly half a light-year. The comet is now less than 2 billion miles from the Sun, falling nearly perpendicular to the plane of our solar system. At that distance temperatures are only about minus 348 degrees Fahrenheit. Yet that’s warm enough for carbon monoxide to sublimate off the surface to produce the dusty coma.
The Orkney News has several articles about comets, you can find them by using our search button.
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