The comet known as C/2014 S3 (PANSTARRS) has a lot going for it. For starters, it's the first comet ever detected without a tail — a trail of dust and ice that sublimates into space as the sun heats the frozen artifacts. It's also thought to have formed in the same time and place as Earth, meaning that the strange comet may contain the same building blocks that formed our planet, kept chilled and pristine and waiting for scientists to study them.