A newly discovered comet has been making a big splash in the nighttime sky of the northern hemisphere. The comet is called Neowise, and if you’re north of the equator, it’s visible to the naked eye. The comet is essentially a flying ball of frozen debris, with a long, gassy tail. It’s about three miles wide. And it’s over 4 billion years old - a remnant left over from the formation of the solar system.