In 1991, Mercury has four retrograde periods: in Capricorn, Sagittarius, Aries, Virgo and Leo. The year opens with a retrograde carried over from the year before; it ends on January 3. The last ends on December 18.
Retrograde periods in 1991
December 14, 1990 – January 3, 1991
Over
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- from Capricorn into Sagittarius
- Length
- 20 days
April 4 – April 28
Over
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- Aries
- Length
- 24 days
August 7 – August 31
Over
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- from Virgo into Leo
- Length
- 24 days
November 28 – December 18
Over
- Shadow begins
- Retrograde begins
- Turns direct
- Shadow ends
- Sign
- Sagittarius
- Length
- 20 days