When describing the transit of the planet across the surface of the star we use specific vocabulary. The transit starts at first contact (t1) and the planet is fully over the surface of the star from at second contact (t2) to third contact (t3) the transit is over at the fourth contact (t4). The time from t1 to t4 is called the total transit duration and the time from t2 to t3 is called the full transit duration. The times from t1 to t2 and t3 to t4 are called the ingress and egress durations.
The duration of different phases of the planet’s transit is tied to the inclination of the planet’s orbit around the star. The inclination of an edge-on system is 90°, and a face-on 0°.
Relevant Section (time indices:1:39 to 3:27)
In the figure below, you can see how the blue planet (i = 90°) and the red planet (i < 90°) are the same size but the red star has a longer ingress/egress time and a shorter total transit time than the blue planet.
