Every retrograde period for a year, in one small response. Retrograde, or vakri, motion is the apparent backwards drift of a planet against the stars, and astrological practice treats those spans as a distinct phase in the planet's behaviour.
Send `year` and nothing else. The response is `data.planets`, an object keyed by planet name, each holding a list of `{start, end}` timestamps in UTC. Periods running across a year boundary are clipped to 1 January and 31 December, so a window beginning at `01-01 00:00:00` actually started in the previous year. A planet that never turns retrograde in that year gets an empty list.
Ten keys are returned: mercury, venus, mars, jupiter, saturn, uranus, neptune, pluto, rahu and ketu. The Sun and Moon are omitted because they are never retrograde as seen from Earth. Rahu and Ketu are derived from the mean lunar node, which drifts steadily backwards all year with no station, so both always show a single window covering the whole year; using the true node instead would produce dozens of spurious few-day entries.
Station times are found by bracketing the day on which longitudinal speed changes sign and then narrowing within it, so they are precise to well under a minute. The same figures appear inside `/api/planetary_details/` bundled with eight other calculations; this endpoint returns the retrograde data alone.
Request fields
Field
Type
Required
Notes
year
integer
required
Year of birth as a number, e.g. 1990. Four digits.