2021
Mercury was retrograde three times in 2021, for 70 days in all: in Aquarius in midwinter, in Gemini in late spring and in Libra in early autumn.
The year wound into a circle, January at the top. Distance from the centre is Mercury’s daily motion; wherever the trace dips inside the zero circle, Mercury is moving backward: three dips, three retrogrades. Each shaded block runs from the station-retrograde day to the station-direct day, both counted, in UTC; the trace is sampled at noon, so it can cross zero a day inside or outside the block.
Three retrogrades
Aquarius, Gemini, Libra.
| Station R | Station D | Sign | Shadow in | Shadow out | Days |
|---|---|---|---|---|---|
| 30 Jan 2021 | 21 Feb 2021 | Aquarius | 15 Jan 2021 | 13 Mar 2021 | 23 |
| 29 May 2021 | 22 Jun 2021 | Gemini | 15 May 2021 | 7 Jul 2021 | 25 |
| 27 Sep 2021 | 18 Oct 2021 | Libra | 6 Sep 2021 | 3 Nov 2021 | 22 |
| Total | 70 |
Every planet in 2021
Ten retrogrades touched 2021 across the eight planets.
One row per planet. The solid band runs from the day of the station retrograde to the day of the station direct, both counted; the hatched band is the shadow on either side, from the day the planet first reaches the degree it will retreat to until the day it passes the degree where it turned. Days are UTC calendar days; a planet’s sign in the readout is its apparent geocentric longitude at noon UTC. Point at the figure, or focus it and use the arrow keys, to read any day.
Computed from the ephemeris and checked against NASA JPL Horizons; times UTC. Every planet’s 2021 windows as data: JSON · CSV · how the dates are computed
Questions
- 01When was Mercury retrograde in 2021?
- Mercury was retrograde January 30 – February 21 in Aquarius; May 29 – June 22 in Gemini; September 27 – October 18 in Libra (station retrograde to station direct). Each window is bracketed by a pre- and post-shadow period — the full dates are in the table above.
- 02How many retrogrades happened in 2021?
- 10 retrograde windows touched 2021 across the eight planets: Mercury 3×, Venus 1×, Jupiter 1×, Saturn 1×, Uranus 2×, Neptune 1×, Pluto 1×. Because the outer planets are each retrograde for four to five months at a time, some part of the sky was retrograde for most of the year.
- 03Which planets were not retrograde in 2021?
- Mars ran direct all year — its next retrograde started October 30, 2022 in Gemini.
- 04What is a retrograde shadow period?
- The shadow (or “retroshade”) is the stretch of sky a planet covers three times: once moving forward, once apparently backward, once forward again. The pre-shadow begins when the planet first crosses the degree it will later retrograde back to; the post-shadow ends when it finally re-passes the degree where it first stationed. The ledger above lists both dates for each Mercury window, and the station chart draws the shadow of every planet’s.
Station alerts
A heads-up before every turn.
An email 3 days before the shadow and each station, one when it turns retrograde, and an all‑clear when it goes direct. Plus a note on each Mercury cazimi.
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