A transit is where a planet is in the sky now, compared with where the planets were in a birth chart.
How does a transit work?
A birth chart is fixed: it records the planets at the moment of birth. The planets keep moving after that, and reading transits means comparing the two. In this method, attention goes to three kinds of change:
- a transiting planet moving into a new sign;
- a transiting planet moving into a new house, one of the twelve sections of the chart;
- an aspect, an angle between a transiting planet and a planet in the birth chart.
The traditional major aspects are the conjunction (0°), sextile (60°), square (90°), trine (120°) and opposition (180°). They are also called the Ptolemaic aspects, after Ptolemy, who defined and used them. The margin allowed around the exact angle is called the orb, and astrologers use differing orbs. For a transit, the Wikipedia article on transits gives a typical allowance of one degree either side of the planet in the chart.
What is an example of a transit right now?
Mercury is retrograde in Scorpio from 24 October to 13 November 2026 (UTC). Retrograde means it appears to move backwards against the stars, as seen from Earth, while it keeps orbiting forward. Take a sample birth chart with the Sun at 15° Scorpio. Transiting Mercury makes a conjunction with that point three times this autumn.
| Date (UTC) | Mercury's motion | What happens |
|---|---|---|
| 13 Oct 2026 | Direct | Mercury passes 15° Scorpio going forward |
| 2 Nov 2026 | Retrograde | Mercury passes it again, going backwards |
| 25 Nov 2026 | Direct | Mercury passes it a third time, going forward |
The retrograde is why Mercury crosses the same degree three times. The dates come from Astronomy Engine, an open-source library (version 2.1.19, geocentric, tropical zodiac). They are UTC dates, so your local date can differ.
Which transits get the most attention?
In this tradition, transits of the fast personal planets (the Sun, Moon, Mercury, Venus and Mars) usually count for less, because these planets move through the zodiac quickly. Transits of the slower planets, Jupiter, Saturn, Uranus, Neptune and Pluto, are read as more noticeable.
A planetary return is a special transit: a planet comes back to the place it held at birth. Jupiter returns about every 12 years and Saturn about every 30 years.
Is a transit a forecast?
Not as an established one. The transit itself can be measured: astronomy records where the planet is, to a fraction of a degree. What isn't established is astrology's interpretation of that position, so a transit is a reading inside a tradition. The Wikipedia article on transits notes the skeptics' view: that vague, general trends let astrologers avoid predictions anyone could check.
What this means for your day
For your day
Do
Find where Mercury is today and look for that degree in your chart.
Don't
Don't treat a transit as a forecast of events in your life.
Questions people ask
How long does a transit last?
It depends on the planet's speed. The Moon spends about two to two and a half days in one sign, while Saturn, which returns about every 30 years, spends about two and a half years in each sign on average.
What is the difference between a transit and a progression?
A transit uses where the planets really are today. A progression moves the birth chart forward in time by a set method instead.
Sources
- Wikipedia: Astrological transit. Definition, a typical orb, planetary returns, progressions, and the skeptics' view on prediction.
- Wikipedia: Astrological aspect. The five Ptolemaic aspects and their angles, and that astrologers use differing orbs.
- NASA StarChild: What does it mean for Mercury to be in retrograde?. Retrograde motion is apparent: the planet does not move backwards in its orbit.
- Wikipedia: House (astrology). Charts divided into houses, usually twelve.