Related Clues:

• Saturn, for one
• Astronomer's sighting
• 5-Down, for example
• Sun circler
• Vulcan, for one
• Jupiter, e.g.
• Saturn or Mercury
• See 31-Across
• Mars, e.g.
• Mars or Mercury
• It has solar heating
• Mercury or Saturn
• Heavenly body
• Krypton, for one
• Mercury, for one