The answer comes from Mercury's real path across the sky: its stations, the shadow period and the sign.
Not yet. The retrograde begins on October 24; Mercury is already on the stretch of sky it will retrace.
Retrograde begins
As of 5:59 AM, Eastern Time
Mercury's path across the sky
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
Its path against the stars, from the start of the shadow to its end; each dot is one day. East is on the left, as you see it in the sky; the thick line is the backward motion. Now
This year's retrogrades
February 26 – March 20
Over
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- Pisces
- Length
- 22 days
June 29 – July 23
Over
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- Cancer
- Length
- 24 days
October 24 – November 13
Now
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- Scorpio
- Length
- 20 days
Why does Mercury seem to move backward?
Mercury circles the Sun in 88 days, far faster than Earth. About every four months, as it passes between Earth and the Sun, it overtakes us. For a few weeks it then seems to slide a little farther west against the stars each night.
It is an apparent motion: the planet doesn't actually turn around in its orbit. A car you pass on the highway also seems to drift backward for a moment; Mercury retrograde is that same change of viewpoint, played out in the sky.
What is the shadow period?
During the retrograde, Mercury backs up over a stretch of sky; once it turns direct, it crosses that stretch again. The weeks from its first entry into that stretch before the retrograde (shadow begins) to its final exit after it (shadow ends) are the shadow period. Each side usually lasts close to two weeks.
In tradition, these weeks are a time to slow down, review and take a second look. This page is a calendar of something happening in the sky; the sky doesn't decide what you do.
How we calculate
The dates come from Mercury's ecliptic longitude as seen from Earth (astronomy-engine, open source). The retrograde begins at the moment the longitude stops increasing and starts to decrease, and ends when it starts increasing again; the moments are found to the minute and shown in Eastern Time (New York).
The sign is the 30-degree slice of longitude Mercury is in (tropical zodiac, with the traditional sign names). Every year from 1930 to 2050 is calculated the same way.
Questions
- When does Mercury retrograde end?
- The answer at the top of the page is calculated from the real sky every time you open it: if Mercury is retrograde, you see the day it turns direct; if not, the next retrograde. All of this year's periods are listed right below, with dates and signs.
- How many times a year is Mercury retrograde?
- Three times in most years, four in some. Each retrograde lasts about three weeks (20 to 24 days).
- Is the shadow period part of the retrograde?
- No. The retrograde runs from one station to the next. The shadow is the weeks before and after, when Mercury crosses the same stretch of sky; here it gets its own dates.
- Can a retrograde change signs?
- Yes. The backward motion covers 9 to 16 degrees of sky; if that stretch crosses the border between two signs, the period is shown with both (for example, “from Aries into Pisces”).
- Why might the dates differ by a day from other sites?
- A station is a single moment; depending on the time zone, it can land on different calendar days. This page uses Eastern Time (New York).