Astronomy Picture of the Day . ... Here Venus, Earth, Jupiter, Saturn, Uranus, and Neptune, were all visible across the sky. Pluto: The Frozen Planet . ... Pluto is usually the most distant planet from the Sun but because of its elliptic orbit Pluto crossed inside of Neptune's orbit in 1979 and will cross back out again in 1999. ... Mercury is the closest planet to the Sun, the second hottest planet (Venus gets hotter), and the second smallest planet (Pluto is smaller). The Sun Erupts . ...