Eclipse is actually an object (planet) which disappears. When it completely disappears it is known as full eclipse, and when it partly disappears it is known as part eclipse.
If we talk in terms of planets: the distance between Sun and Mercury is 36 million miles approximately, Venus is 6 crores 7 millions miles far and Earth is 9 crores 3 million miles far. Moon revolves around Earth and the distance between them is 2 lakhs 40 thousand kilometers. So, that is how Moon comes between Mercury and Venus, Sun and Earth.
Similarly, Mars from Sun is 14 crores 20 lakhs miles, Mercury 48 crores and 30 lakhs and Saturn some 88 crores 60 lakhs miles away. This is how Sun gets located between Earth and these three planets. When Mercury and Venus are located far from Earth during transit, then Sun comes between these two planets and Earth. Sun does not transit through Earth and Moon.
When two planets are located near the same point of one sign, then a Yoga is created. In this situation each planet tries to influence both the sides with their rays, which is called Vrit (circle). Sun is the most powerful planet among all, therefore its one circle (Vrit) completes in 170 minutes, of Moon in 120 and of the remaining planets in 70 minutes. Generally, when two friendly planets form a conjunction Venus also has its influence and when two enemy planets are located at one sign near one point it has an inauspicious influence.
When any planet forms a relationship or is in conjunction with Sun, then eclipse takes place, and as a result the planet becomes weak. Whereas if any planet forms a conjunction with Moon it becomes strong.
When any planet is 50 minutes away from Sun it is completely combust. In the distance of 100 minutes the combust of planet will reduce and in 150 minutes the influence will come to an end and the planet will be fully awake. The conjunctions of all the planets are considered significant in Vedic Astrology, while in Western Astrology only the conjunctions of Sun and Moon with other planets are considered significant.
In Vedic Astrology planetary conjunction is considered important and significant for auspicious Muhurtha, predictions, movement of transit and for other auspicious works. This planetary conjunction also has its influence on individuals, whether auspicious or inauspicious.