A long-period comet that hasn’t been near Earth for 50,000 years is now visible with the naked eye. The comet known as C/2022 E3 (ZTF) is a dazzling green color chiefly because of the presence ...

Earth's oceans were once green, according to a new study. Carl Sagan, the host of the popular TV show Cosmos, once described Earth as a 'pale blue dot' when explaining an image taken by Voyager 1.