What you’ll discover
- What 3:2 resonance means
- Why Mercury speeds up near perihelion
- Where the apparent reversal comes from
Show notes
Mercury does not simply keep one face toward the Sun. Its three-to-two resonance means it rotates three times during two trips around the Sun.
Near perihelion its orbital angular motion briefly outpaces the rotation seen from the surface. The Sun’s apparent motion can stall and reverse before ordinary motion resumes.
Key facts and named entities
- Three rotations for every two orbits
- Orbit: strongly eccentric
- Effect: temporary apparent solar reversal
- Mapped by: MESSENGER
Chapters and key moments
Sources and further reading
- NASA: Mercury factsPrimary or mission source
- ESA BepiColomboPrimary or mission source
Take it outside
Download the field-source checklist
A plain-text checklist for checking dates, locations, claims, image rights, and primary sources before an observing session or science post.
Gear used or relevant
This companion makes no product recommendation. The story is fully usable with the video and primary sources above. Commercial gear will appear only when it solves a practical observing problem and Rick’s first-hand status is documented.
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