Astronomy / Calendar
Is Mercury Retrograde? Dates and Calendar
Check Mercury’s motion right now, explore six years of retrograde dates for five planets, or check a date in your time zone.
Is Mercury Retrograde? Dates and Calendar: Shows whether Mercury is retrograde now, its next retrograde start and countdown, and its shadow status. The calendar covers the previous year through four years ahead for Mercury, Venus, Mars, Jupiter and Saturn, including complete periods that cross a year boundary. Check any date and time from 1900 to 2100, save a share card or add Mercury’s retrograde periods to your calendar. Astrology is a cultural and entertainment practice; this result makes no predictions. Runs 100% locally in your browser with zero server file uploads.
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THE VIEW FROM EARTH
Checking Mercury’s motion…
Retrograde calendar
Times shown in UTC. Periods touching the year range are included in full.
| Retrograde starts | Direct again | Tropical signs | Pre-shadow starts | Post-shadow ends |
|---|
Shadow dates follow common astrological usage: the first crossing of the eventual direct-station longitude, then the return to the retrograde-station longitude. They are not a separate astronomical motion.
Check a date
The time uses the display zone selected above. A repeated local time uses its earlier occurrence; a skipped daylight-saving time moves forward by the size of the gap.
A change in our view, not in Mercury’s orbit
Retrograde is an apparent backward motion against the background sky, seen from Earth because planets travel at different orbital speeds. No planet physically reverses its orbit. Here the direction is measured in geocentric ecliptic longitude.
Astrology traditionally associates Mercury retrograde with communication, travel and technology. Astrology is a cultural and entertainment practice; this result makes no predictions.
The astronomy: relative orbits and apparent motion
Geocentric ecliptic longitude measures a planet’s apparent direction around the sky from Earth. A station occurs when its longitudinal speed changes sign. The geometry depends on relative orbital motion: Mercury and Venus pass between Earth and the Sun, while Earth overtakes the outer planets. No physical orbit reverses.
A worked example computed by the same engine: Mercury stations retrograde on 1 April 2024 at approximately 27.22° tropical longitude and stations direct on 25 April at approximately 15.98°. The decrease is about 11.24° over 23.61 days. The live page also gives an example from its displayed year range. Both describe apparent motion from Earth.
Source: Jean Meeus, Astronomical Algorithms, second edition, Willmann-Bell, 1998. The book explains planetary coordinates and the geometry behind geocentric positions. Tropical signs here divide longitude into twelve equal 30° sectors; they are not the unequal astronomical constellations.
How the dates and shadows are calculated and checked
Positions are computed with astronomy-engine, an MIT-licensed astronomical library. The astronomy-engine documentation (https://github.com/cosinekitty/astronomy) describes its geocentric positions and accuracy. The calendar scans at most one day at a time for Mercury and two days for the other planets, then bisects each speed sign change to a minute. Angular differences handle the wrap from 359° to 0°.
Pre-shadow and post-shadow boundaries are solved separately as longitude crossings before and after each retrograde period. Test stations from 2024 through 2030 are cross-checked against independently generated Swiss Ephemeris 2.10 reference values; these reference values are used only in tests. Rounded times are estimates from the astronomical model, rather than guarantees of observational accuracy to a minute.
Plain-text sources: Meeus, Astronomical Algorithms; astronomy-engine documentation. Swiss Ephemeris reference information (https://www.astro.com/swisseph/) describes the independent comparison ephemeris. Astrological meanings and shadow labels are cultural and entertainment traditions, without predictions.
How to use it
- Read Mercury’s current status in your browser’s time zone, or switch the display to UTC.
- Choose a planet tab for its retrograde and shadow dates, or check a specific date and time for all five planets.
- Save a share card, copy the current answer or download Mercury’s calendar as an ICS file.
Privacy & limitations
Dates and calculations stay in your browser. Nothing you enter is uploaded.
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Frequently asked questions
What is Mercury retrograde?
Mercury retrograde is an apparent backward movement against the background sky as seen from Earth. Relative orbital speeds change our viewing direction. Mercury keeps moving forward around the Sun; its orbit does not reverse.
How often does Mercury go retrograde?
Mercury goes retrograde about three times a year, sometimes four, for about three weeks each time. The dates and exact lengths vary, so the calendar computes the stations for each period.
What is the Mercury retrograde shadow period?
In common astrological usage, the pre-shadow begins when Mercury first crosses the longitude where it will later station direct. The post-shadow ends when Mercury returns to the longitude where it stationed retrograde. Mercury is moving direct in both shadows. These labels are a tradition, not an additional astronomical reversal.
Is Mercury retrograde real?
The apparent motion is real astronomy and can be calculated and observed. Astrology traditionally associates Mercury retrograde with communication, travel and technology. Astrology is a cultural and entertainment practice; this result makes no predictions.
Which planets go retrograde?
All the other planets can appear retrograde from Earth: Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune. This calendar covers the first five. The Sun and Moon do not show this same longitudinal retrograde motion. Earth is the viewpoint, so it has no geocentric retrograde period.
Why do retrograde dates differ between time zones?
A station is one instant worldwide, but its calendar date may differ between time zones. Times initially use the zone named by your browser, including daylight-saving changes at the event date. Select UTC for a shared reference. ICS events use UTC so calendar apps can display their own local time.
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