Retrograde calendar.

Retrograde is an apparent reversal of motion seen from Earth — it doesn't mean the planet is actually moving backward. It's a perspective effect from Earth's faster orbit overtaking an outer planet (or an inner planet's geometry relative to the Sun). The classical reading is that the function the planet governs — communication for Mercury, relationships for Venus, drive for Mars — turns inward during the retrograde window. Things stall externally; review and refinement happen internally.

Mercury retrogrades 3–4 times a year for ~3 weeks each. Venus retrogrades roughly every 18 months for ~6 weeks. Mars retrogrades every ~26 months for ~10 weeks. Jupiter retrogrades once a year for ~4 months. Saturn retrogrades once a year for ~4.5 months. The outer planets (Uranus, Neptune, Pluto) retrograde roughly half the year each. The classical advice scales with the retrograde's natural frequency — Mercury's are routine course-corrections; outer-planet retrogrades are not particularly noteworthy.

Mercury retrograde is the most-discussed retrograde in modern astrology, mostly because Mercury governs communication, contracts, travel, and devices — visible domains where friction is felt immediately. The classical advice is to be careful with new contracts, expect communication misfires, back up data, and use the window for review rather than launch. Few practitioners read it as an actual problem; it's the same recurring 3-week course-correction we get four times a year.