NASA's Hubble Space Telescope team
Likens comets to dirty snowballs with spectacular multimillion-mile-long tails. Comets look fuzzy, but they have a packed nucleus of ice and dust.
Hubble has now confirmed
the largest comet nucleus ever discovered, a stunner of a snowball that could be 85 miles (137 kilometers) across.
Hubble is a joint project
of NASA and the European Space Agency. It often gazes at distant galaxies, but scientists were able to use it to help measure the nucleus of comet C/2014 UN271
Remember comet Neowise
which came close to Earth for a visit in 2020? Neowise's nucleus is about 3 miles (5 kilometers) in diameter.
The 4-billion-year-old comet
hailing from a theoretical distant comet "nesting ground" called the Oort Cloud was first observed in 2010.
Hubble observations in 2022
were needed to discriminate the solid nucleus from the huge dusty shell enveloping it, with help from radio observations. That dusty shell is called a coma.