Ceti is a sun-like star ~ 3.6 pc from earth. assume that an earth- like planet is orbiting t ceti in a circular orbit 1 au from the star. the orbit will subtend a half angle of 0.278". 1 radian 206265" if you have a diffraction limited telescope observing 1u light at maxi- mum elongation, how large would your telescope have to be to produce an image of the system with the image of the star separated from the image of the planet by a dark region at least as large as the image of the star?