Pluto, Neptune, Saturn, Chiron, Uranus, Venus are retrograde

Stations and shadows

The retrograde begins at the station: the planet slows, stops against the stars and starts to move backwards. Weeks later it stops again and turns direct. Both moments are computed here to the minute, with the degree the planet stands on. Mercury does this three or four times a year for about three weeks; Venus every eighteen months for about six; Mars every two years for roughly ten weeks; the outer planets for four to five months every year.

Before the retrograde, the planet first passes the degree it will later return to. That first passage marks the start of the pre-retrograde shadow. After turning direct, it needs a few more weeks to get back to the degree where the retrograde began; that is the end of the post-retrograde shadow. Astrologers who work with shadows read the whole stretch as one story in three passes. The shadow dates are here for them; the stations are what everyone else means by "Mercury retrograde".

All of it is in retrogrades.json, CC BY 4.0.