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, making it larger than the state of Rhode Island. 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.
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C/2021 A1, also known as Comet Leonard, is expected to reach peak size and visibility the weekend of December 10-12 in the pre-dawn sky. It will be at perihelion on January 3, 2022.
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Comet C2020 F3 NEOWISE is shining brightly in the dawn sky throughout the month of July.
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Comet SWAN (C/2020 F8), discovered by Australian amateur astronomer, Michael Mattiazzo using the Solar Wind Anisotropies camera on NASA’s Solar and Heliospheric Observatory (SOHO), is now a naken eye object visible from the Southern Hemisphere.
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Comet C/2019 Y4 ATLAS, discovered in December 2019 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Mauna Loa in Hawaii is approaching the inner solar system. It is currently observed to be disintegrating.
Interstellar comet 2I/Borisov, discovered in 2019, has been seen breaking apart in March 2020.
Hubble Space Telescope observations indicate that fragments of the comet are drifting away, as reported in the Astronomer’s Telegram on April 2, 2020.
Comet 2I/Borisov, discovered on August 29, 2019, has astronomers intrigued as it is only the second known object to be have an orbit and velocity that suggests it is of interstellar origin. It’s orbit has an eccentricity of about 3.5. It will reach perihelion on December 7, 2019.
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New study shows a certain family of comets contain water similar to earth’s water.
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The comet 46P/Wirtanen (46P) is set to make a close approach to Earth this weekend. At its closest, 46P will pass a mere 11.7 million km from our planet.
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ESA’s Rosetta mission has concluded with a controlled descent into Comet 67P/Churyumov–Gerasimenko. “The descent gave Rosetta the opportunity to study the comet’s gas, dust and plasma environment very close to its surface, as well as take very high-resolution images… after becoming the first spacecraft to orbit a comet, and the first to deploy a lander, Philae, in November 2014.” More