Hi everybody,
So I know that you would have to look at where a transiting planet falls in your natal chart to be able to tell where it's affecting you, for example, the upcoming Mars retrograde in Sagittarius will naturally fall on my 10th house as I'm a Pisces rising, and also 2nd house (where my natal aries is) and 9th house (where my natal Scorpio is). Right?
My question though is whether or not it will also affect the house where my NATAL MARS (or whatever planet we might be talking about) is. My natal mars is on my 6th house near the 7th house cusp, does that mean that the TRANSITING retrograde will be affecting that area too?
There are at least two distinct ways of looking at Transits. The first is looking at the transits of natal planets by currently transiting planets. This view tends to see no effects unless two planets are involved. So Mars going Retrograde in Sagittarius will have no affect unless it is in aspect to a natal planet including itself). This approach would also limit the range of effectiveness of the Transit, to a few degrees before and after the natal planet.
The second and older way of looking at Transits, is simply the movement of a planet through a sign. So Mars transiting through Sagittarius will have an effect. It might be more subtle than the transit of a planet but it is there. So Signs that lie in aspect to Sagittarius may also receive some influence. This view is based on Mars casting its
rays outwards in the seven directions (two sextiles, two trines, two squares and an opposition). Most modern writers wouldn't see Pisces as being in any way influenced by Mars in Sagittarius unless there is a natal planet in Sagittarius and only then when Mars comes into orb.
The two approaches aren't mutually exclusive. Hellenistic and early Medieval Astrologers, would see Pisces being generally affected in the example above but the effect would be at its most intense when the rays from Mars hit a planet in Pisces.
Generally effected would depend on the transiting planet involved and the aspect that the ray is trying to form. Mars and Saturn were seen as naturally tending to represent difficulties, restrictions, things going wrong. If they were in Square or Opposition, then the affect of their transit would tend to be experienced as difficulties. Jupiter and Venus generally have a constructive or beneficial effect and their rays will tend to be supportive, especially when attempting to form Trines or Sextiles. Where no other planet is involved the most that you might identify is a general background tendency.
As strictly speaking, to transit means to move through, the older meaning is completely correct it's just that both approaches recognse that transits without aspecting another planet are weaker than transits which do result in aspects to other planets.
You are right, the area of life affected would be either the area of life denoted by the sign Mars is transiting, or the area of life of denoted by the houses occupied by the signs aspected. Where two or more planets are aspected, then the areas of life that they rule will also be affected.
The house occupied by natal Mars will be affected when transiting Mars aspects it either by sign (weak) or by degree (strong)
Also, I understand how reading daily horoscopes based off what our Ascendant works since that information alone tells us what signs are ruling the rest of the houses, but what are the "normal" SUN SIGN horoscopes we see everywhere based off?
Sun sign horoscopes are cast on the assumption (mostly wrong) that you were born when your Sun sign was rising. So if you were born with the Sun in Aries, the sign of Aries would be your Ascending sign.
Sun Sign Horoscopes use Whole Sign Houses. So the whole of Aries is your first house and so on, round to Pisces which is your twelfth house.
Now such horoscopes actually do use transits in the old sense of a planet moving through a sign (and therefore a house, using Whole Sign Houses). So when your horoscope might predict something good in terms of romance for Aries because Jupiter is transiting your fifth house, It basically means Jupiter is in Leo and being a benefic, Jupiter brings good thing to that area of your life.
Note, these horoscopes have no idea where your natal planets are, other than the Sun was in Aries (or whatever sign you are reading), so all Transits have to be in the original meaning, rather than the later meaning of transiting planet aspecting a natal planet.