What are transits?

When observing stars, we can detect how much light we receive from them every second – this is called their flux. If a planet were to pass between the star and our telescope when we are looking at it, we might hope to see a small black dot making its way across the image of the star. However, stars are too far away to resolve such detail. Instead, what we observe is a reduction in the amount of light we receive from the star during the time that the planet is in front of it. This fall in intensity is our evidence that we may have detected a planet.