How to use it
- Enter the Date and the Time you want. If you do not know the time, tick I do not know the time: the planets are then shown for 12:00 local time.
- Type the Place and pick it from the list, or tick Enter coordinates instead. The place sets the time zone.
- Click Calculate. The table lists the five planets with their retrograde flags; the Retrograde column shows Yes for a planet that is moving backwards.
- Read the dates under How long Venus and Mars stay in their signs to see when each entered and will leave its sign.
Where the planets are
Each planet's sign is the zodiac part that contains its geocentric ecliptic longitude at that moment, measured from the true equinox of the date. Mercury, Venus, Mars, Jupiter and Saturn are the five planets visible to the naked eye, so they are the ones astrologers have used for the longest time.
A planet is retrograde when its longitude is decreasing as seen from the Earth. This is an effect of the viewpoint: the planet is not moving backwards. The calculator reads the direction from the change of longitude over one day.
How long Venus and Mars stay
Venus and Mars can stay in one sign for different lengths of time, because retrograde motion can take them back across a sign boundary. The calculator steps back and forward one day at a time from the chosen moment until it finds the last entry and the first exit, then bisects each to the second.
The dates are shown in the time zone of the place you choose. Where the search reaches 400 days without finding the change, the page says so instead of guessing.
What is not covered
- Uranus, Neptune and Pluto, and the Sun and Moon; the birth chart calculator gives all of them.
- Planetary hours and the exact dates on which a planet turns retrograde or direct, which need a calculation of their own.
Worked example: New York, 4 July 1990, 14:30
At that moment Mercury is at 15°00′ Cancer, Venus at 11°35′ Gemini, Mars at 24°38′ Aries, Jupiter at 20°09′ Cancer and Saturn at 22°45′ Capricorn. Saturn is retrograde; the other four are direct.
Venus entered Gemini on 24 June 1990 at 20:14 and leaves it on 19 July 1990 at 23:40 New York time. Mars entered Aries on 31 May 1990 at 03:10 and leaves it on 12 July 1990 at 10:44.
Frequently asked questions
What does a retrograde planet mean in this table?
Yes in the Retrograde column means the planet's longitude is decreasing as seen from the Earth for that moment. The planet is not reversing; astrologers read retrograde periods as times for review, a symbolic reading.
Why does Venus stay in one sign for different lengths of time?
Venus moves about a degree a day on average, but its motion changes when it goes retrograde. It can stay in one sign for a few weeks or, near a turn, for a much longer time.
Do I need the exact time for the planet signs?
Usually not. Mercury moves about two degrees a day at most, so the time matters only near a sign boundary. Without a time the calculator uses 12:00 local time and says so.
Why are the dates in my time zone?
The dates follow the clock of the place you choose: a moment late in the evening in New York can already be the next day in London.
Does the calculator store what I enter?
No. The date, time and place stay in your browser and are not stored or sent to us.
Sources
- astronomy-engine, the MIT-licensed library that calculates the planet positions
- JPL Horizons, the NASA ephemeris used to check the positions
- IANA Time Zone Database, the historical clock rules of each zone
- GeoNames, city coordinates and time zones (CC BY 4.0)
Figures and text last checked on Tuesday, November 10, 2026.