How to use
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The banner at the top tells you whether Mercury is retrograde, in a shadow period or direct right now, with a countdown.
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Pick a year with the arrows or type it in (1900–2100).
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Your browser’s time zone is selected automatically; change it to see the times anywhere in the world.
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Each card lists pre-shadow start, station retrograde, station direct and shadow end with the exact degree.
What the four dates mean
A Mercury retrograde cycle has four key moments. The pre-shadow begins when Mercury first crosses the degree where it will later turn direct. It then slows to a station and turns retrograde, travels back over the same stretch of the zodiac for roughly three weeks, stations direct, and finally leaves the post-shadow when it passes the degree where it originally turned retrograde. The coloured strip above the cards shows how these phases are spread over the year.
How the dates are calculated
Positions come from a full planetary ephemeris (geocentric, apparent, tropical zodiac). Stations are found where Mercury’s daily motion changes sign and refined to about a minute; shadow dates are found by searching for the exact moments Mercury crosses the station degrees. Nothing is copied from a printed table, so you can check any year from 1900 to 2100.
Mercury retrograde in the astrological tradition
Mercury is associated in astrology with communication, travel, paperwork and trade. Its retrograde phases are traditionally treated as a time to review, revise, reconnect and double-check rather than as something to fear. The sign in which a retrograde falls is said to colour its themes. Read it as cultural tradition and a prompt for reflection — the astronomy is real, the interpretation is symbolic.
Frequently asked questions
How often is Mercury retrograde?
Three or four times a year, for roughly 19 to 24 days each time. Including both shadow periods, a full cycle lasts around two months.
Why do some websites show a different day?
Stations happen at a precise instant, so the calendar date depends on the time zone. A station at 02:00 UTC is still the previous evening in the Americas. Choose your zone above to see the correct local date.
Does Mercury really move backwards?
No. Mercury, on its faster inner orbit, overtakes Earth as it passes between us and the Sun, so for a few weeks it appears to move backwards against the stars. It is a line-of-sight effect.
What is the shadow period?
It is the stretch of the zodiac Mercury covers three times: once before the retrograde (pre-shadow), once backwards during it, and once again after it (post-shadow).