It looks too much of information but all very necessary. So, let’s cover all the points one after the other – 

What is Planetary Transit? – First of all, what is a planetary transit? Planetary Transit is a time-bound movement of every planet in sky where it goes from one sign to another sign or one portion of the sky to another. We have our birth chart and planets placed there. But it is only a picture of sky taken at the time of birth. Planets continued to move before and after our birth and they are/will continuously move in the sky till eternity and continue to impact our life. So, when a planet transits from one sign to another or within a sign, it can cause some events to take place as per position in the chart. Now, every planet has different speed of transiting a sign and that should be taken into consideration as well. These are, Moon – 2 days and 6 hours, Mercury – about 23 days, Venus - about 25 days, Sun – about 1 month, Mars – about 45 days, Jupiter – about 13 months, Saturn – about 2 and half years, Rahu/Ketu – about 1 and half year. Uranus-Neptune-Pluto have broader orbits and take 7 to 15 years time to transit a sign. When Venus-Mercury-Mars are retrograde during transit, they take more time than given here. 

Transit seen from? – First big confusion and matter of debate is from which house/sign in chart we should observe transits. People have different opinions. From Ascendant to Moon Sign to Sun Sign to Divisional Charts, all are advocated by different Astrologers. Mostly, people see transits from Ascendant and Moon. I always see everything from Ascendant. We need to understand that Moon sign was used in a time when we didn’t have enough tools to calculate accurate time of birth. In absence of that, Moon Sign becomes the next closest point of distinction between two people. So, ancient Astrologers preferred Moon sign. But now we have enough technology to record time in seconds also. In that case, using Moon Chart doesn’t make any sense. But it doesn’t mean Moon Chart is completely useless. Planetary Position and Transits from Moon show that how our mind reacts to different events and situations in life as Moon represents Mind. So, best example I can give here is that for 99% of people child birth is good happy event but there are still people who want to see birth of a male child, so birth of a female child may not be received well by mind. So, this is what Moon Chart shows. Event remains the same, only our perception towards event changes. So, if you are looking for prediction of events, check things from Ascendant Chart. 

Nature/Dignity of Planet – Now, 1st most important criteria to judge a planet’s transit is to check its nature and dignity in birth chart. Like, a benefic planet in good dignity in birth chart will give results easily during transits but a malefic planet in bad dignity will make us put lots of efforts before giving any results. Jupiter in own sign can give good results during transit Vs Saturn in enemy sign. Even if malefic planets are exalted, it is in their nature to make us do hard work and even if benefic planets are debilitated, they will still provide something. 

Mahadasha/Antardasha – This I consider as the most important criteria of judging a transit. We should always focus on transits of those planets whose dasha we are going through. So, if someone is under Saturn-Mars dasha and they are activating houses related to real estate in birth chart then we need to give preference on transit of Saturn-Mars. During that dasha, no matter where Jupiter-Venus (karaka of relation) are transiting, marriage is a distant possibility. If any concrete event can happen during this time, then it is about Real Estate or other things Saturn-Mars are activating. Yes, if Saturn-Mars are also activating marriage related houses, then there can be marriage as per their and Jupiter-Venus transit. So, I mean to say that Mahadasha/Antardasha planets activate houses in chart and transits impacting same houses are triggering point towards the event related with those houses. Mahadasha is Rifle, Antardasha is Bullet and Transit is the Trigger. Only exception here is again Saturn. No matter you are under Saturn dasha or not, Saturn transit will always play an important role, for the simple reason that its speed is so slow in transit that it will catch you any day during 2.5 years of transit. 

Planets as Karaka and House Lord – Now, when it comes to results, every planet gives results, during dasha/transit, of the things it is Karaka of and then houses it rules. So, suppose you are under Mars MD. Mars is karaka of Courage, Will-Power, Real Estate, Brother, Male Friends etc. So, Mars MD/Transit will first of all will bring the results of these karaka things. Then if you are Libra Ascendant, results will be seen of 2nd house of Wealth/Family and 7th house of Marriage/Spouse. So, Mars MD, and transits within it, will be very much a relationship oriented time. Other results can be seen of houses planet aspects or nakshatra it rules where other planets are sitting or where its own nakshatra lord is sitting. 

House/Sign involved in Transit – Now, you will get the results of the planet’s karaka things and houses it rules from where it transits. So, suppose someone is Aries Ascendant, Jupiter rules 9th house and 12th house of his chart. So, Jupiter becomes a Religion/Spirituality or travelling related planet for him. Now, if Jupiter is placed in 3rd house in Gemini in birth chart, then it is in fall sign. So, its dignity is kind of average. Now, Jupiter is transitting Virgo in 6th house for Aries Ascendant people. So, person will get results of 9th house and 12th house from 6th house. So, he might travel due to his daily office work or he might take higher education of Law/Medicine etc. But all the while he will feel frustrated as not only Jupiter is in fall sign in birth chart but it is also in fall sign in transit, i.e. Virgo. He won’t be satisfied by results of his travels or higher education. As a benefic planet Jupiter will still provide him but he won’t feel great about it. Condition apply that person must be under Jupiter dasha to feel the same. Like this, person will get results of karaka things and houses it rules through the house/sign it transits and the end result will depend on nature and dignity of planet in birth chart and transit both. 

Aspects of Planet Transiting – Then every planet will give results of the houses it aspects during transit. So currently, Saturn is in Sagittarius. For Aquarius Ascendant people, it will be in 11th house and will give results of the houses it aspects from 11th house, i.e. 1st house, 5th house and 8th house. Like this, every planet will give results of houses it aspects during transits. Also, if many planets together aspect a single house during transit then it is almost sure that things related to house thus aspected will happen because of huge accumulation of energy at one house. 

Planets transit over another Planets – Biggest impact of transit of planets and triggering point of events happen when planets transit over other planets of birth chart or of current transit only. Like, last year we had seen Saturn-Mars transiting in Scorpio between Feb to Aug, 2016. Saturn-Mars together in Scorpio only indicated lots of stress and chaos and we have seen violent and terrorist activities took place even in those countries which were never known for Terrorism targets. So, Saturn-Mars, 2 strongest malefic planets, transiting over each other caused all the nuisance. Now, if someone is also born with few planets in Scorpio, then it was even more stressful transit for him. Being a Scorpio Ascendant myself, I remember that I almost stopped driving vehicle unless it was too urgent or necessary and that too, I drove at minimum possible speed with all the safety gears on. Now, it can be benefic too. If Jupiter is transiting over Moon and both are in good dignity then it can bring benefits too. Here we also need to take note of the fact that which houses are ruled by each transiting planets as events will be related to houses ruled by these planets. Like in above example, Saturn-Mars transit for Scorpio Ascendant can bring events of 1st house, 3rd house, 4th house and 6th house as these houses are ruled by Saturn-Mars for Scorpio Ascendant. 

Position of Nakshatra Lord – Last but not the least, during transit in a sign, a planet moves through 2 and half nakshatra. So, whenever it is transiting in a nakshatra, we need to look at position and dignity of nakshatra lord in birth chart and transit both. Like, if Jupiter is in Hasta nakshatra now, then look at position of Hasta Lord Moon in birth chart and transit. As Moon changes its sign after every 2 days, so in case of Moon, it is better to check only the dignity in birth chart. 

Conclusion – It may look too much to look for but with practice, everything becomes quite natural. And as always, everything is in addition. Astrology is all inclusive.