Transits for Astro‑Trading

A Windows Program to Calculate Exact Dates of Geocentric and Heliocentric Planetary Transits

This software, developed by Peter J. Meyer, is fully-functional and not time-limited.  It runs on Windows (XP to 11).  To obtain a download link send a request to the developer at with the program name (or just TAT) plus your name and email address.

Jupiter-Uranus square 2013
Click for full size
World planetary transits (a.k.a. mundane planetary transits) occur when two moving planets possess a particular angular relationship (called an aspect) with each other (e.g. conjunction, opposition, trine, square, etc.) with respect to a central point, which is either the Earth in geocentric astrology or the Sun in heliocentric astrology. A transit (more exactly) is the period during which two planets remain continuously in a particular aspect with each other. This software calculates the exact dates and times at which transits between selected planets (including the Sun in geocentric astrology, and the Earth in heliocentric astrology) begin and end (relative to chosen orb values from 1° to 15°).

This software uses a new method for displaying the periods of planetary transits, known as transit tables. The two transit tables below (for orbs of 5°, 3° and 1°) show that heliocentric transits differ significantly from geocentric transits. This is because in geocentric astrology (but not in heliocentric astrology) a planet may be retrograde (that is, appear to move backwards). Consequently transits are much more regular in heliocentric astrology than in geocentric astrology, as the geocentric and heliocentric transit tables below show (only conjunction, square and opposition are included):

geocentric transit table
heliocentric transit table

The heliocentric conjunctions of Jupiter and Saturn occur once every twenty years (and a few months). The period varies due to the variation of the speed of these planets in their elliptical orbits around the Sun.

User Manual