A ‘Front-Row Seat’ to the Birth of a Comet - The New York Times
Astronomers are watching an object transform into a hyperactive comet that will head toward the inner solar system in the coming decades.
Astronomers recently witnessed an enigmatic icy object in Jupiter’s shadow begin its transformation into a type of comet, one that sticks close to the sun.The object, named LD2, is called a Centaur, an icy proto-world named after mythological part-person, part-horse creatures because these orbs can behave like an asteroid and a comet.The migration of comets and soggy asteroids from the fringes of our stellar neighborhood toward the rocky inner worlds was like a water delivery service in the early days of the solar system, slaking the thirst of planets drying out because of giant impacts and planetwide magma oceans.In 2019, the Asteroid Terrestrial-impact Last Alert System or ATLAS, a pair of NASA-funded telescopes developed by the University of Hawaii that search for potential city-killing and country-crushing space rocks, spotted an object that appeared to be tracing Jupiter’s orbital path.Like a cyclist going around a velodrome encountering a sudden steep drop, LD2 was thrown off-balance, putting it on course to fall toward, and ultimately remain mostly within, the inner solar system.
But its coma lacks water vapor, said Teddy Kareta, a planetary astronomy graduate student at the University of Arizona and co-author of the study.
Being close enough to the sun, its water ice will be persistently obliterated, fueling a water vapor coma.