What Is a Comet? Ice, Dust, and a Tail That Points the Wrong Way
In 1997, Comet Hale-Bopp was visible to the naked eye for 18 months, longer than any comet in recorded history. It was a chunk of ice and dust maybe 60 km across, sublimating in sunlight, and it put on a show for the entire planet. That is what a comet does when it comes close … Read more