Transit of tres-1. the planet tres-1, orbiting a distant star, has been detected by both the transit and the doppler tech- nique, so we can calculate its density and get an idea of what kind of planet it is. a. using the method of mathematical insight 13.3, calculate the radius of the transiting planet. the planetary transits block 2% of the star’s light. the star tres-1 has a radius of about 85% of our sun’s radius.