The other commonly used approach in astrology is the use of transit charts. While the natal or birth chart represents energies a person carries and matures with throughout life, the transit chart indicates which of all these energies from the birth chart will be prominent at particular points in time. This information is garnered by overlaying the planets in the natal chart (i.e. where the planets were when the person was born) with the location of the planets at a later point in time such as the present. An example of a transit chart is shown below.
Examining the transit chart above, we see that we have an inner chart and an outer chart. In this case, the inner chart is nothing more than the same natal chart shown in all the previous tutorials. The outer ring of planets depicts where the planets were at some other point in time, in this case, on November 6, 2008 at a little after 2:30 in the afternoon.
If we were to create an animation of the chart above by plotting the location of each planet at the same time for many days in a row, the planets on the inner circle would never move as they represent the planets at the time of birth. However, the planets in the outer ring move over time. For example, the moon travels the full circle counter-clockwise in about 28 days. The sun takes 365 days to go full circle and Pluto at the opposite extreme takes 248 years to go full circle.
As a side note, there are certain times when the planets appear to be going backwards due to a parallax phenomena as the vantage point is from the earth instead of the sun. When this happens, we say the planet is retrograde 
. For an animated view of why retrograde happens, you can look at this web site on retrograde. Times of retrogrades can cause screwy things to happen such at with Mercury retrograde, a time when appointments are often missed, initiated projects and contracts are not thought through well, and decisions made during this time often have to be revisited and corrected.
Once a person is familiar with the natal chart, using the transit chart is quite straightforward. When a planet in the outer circle (transiting planets) aspects a planet in the natal chart, it’s like giving the planet in the natal chart an extra boost of energy which is colored by the energy and characteristics of the transiting planet.
Referring to the figure above, let’s take an example to show how this works. Note that transiting (outer circle) Sun 
in Scorpio 
in the 1st house is square 
(90°) natal (inner circle) Venus 
in Aquarius 
in the 4th house. So, in the natal chart there is a lifetime energy of Venus in Aquarius in the 4th house which can be interpreted as desiring relationship in the home (4th house) in ways that also allows room for freedom . That natal energy is being lit up by the transiting Sun in Scorpio in the 1st house which will add a prominent personality (1st house) that wants to explore deeply . One way this combination could manifest is to create an energy to make adjustments in relationship in the home environment ( in in 4th house) by exploring beneath the surface ( in in 1st house).
Some transits last much longer than others. If the transiting (outer circle) Moon 
is aspecting one of the natal planets, the effect only lasts a few hours. At the other extreme, if the transiting Pluto 
is aspecting one of the natal planets, the effect lasts for a couple of years because Pluto moves so slowly. These long lasting transits have very powerful effects simply because that energy created is sustained over a long period of time.
A good example of one of these significant transits is the time in a person’s life when transiting (outer circle) Uranus 
opposes 
natal (inner circle) Uranus . Because the orbits of planets are elliptical and not circular, this significant transit does not occur at the exact same age in people’s lives, but instead slowly changes each year and ranges from the late 30′s to the mid 40′s in age. Currently this is occurring for people around the age of 43. When Uranus energy is prominent, a person has an increased desire to do things they have always wanted to do. During these times, people tend to go through significant changes ranging from divorces, purchasing shiny new sports cars, moving, changing jobs and dancing naked on a table with a lampshade over their head. Some know it as the midlife crisis.
Next: Fate versus Free Will
