Hercules, a constellation of the Northern Hemisphere. It is best seen during the summer. It was represented by the ancient Greeks as the kneeling figure of the hero Hercules. Near the western edge is the globular star cluster Messier 13, comprising more than 50,000 stars about 30,000 light-years from the earth. Only a few stars of Hercules are brighter than fourth magnitude.
Since the 19th century, humans have wondered about the prospect of life on Mars. While we haven't sent anyone to the Martian surface, we have sent spacecrafts, which have gathered a good amount of information on what it's like on Mars. How is it different from Earth? How is it similar? And could life really have existed there long ago, or exist in the future?
The moon is often the largest object in the sky outside of the sun. What is the moon made of, how did it form -- and why do people blame it for their strange behavior?