To calculate the angular size of an object with diameter D as observed from a distance d we compute D d and then convert from radians the natural angular rheasure to the more common degrees arcminutes arcseconds system a D d angle a in radians The planet Mars has a diameter of 6800 km What is the angular size of Mars in arcseconds when it is observed at a typical distance of 270 million kilometers from Earth Using a calculator express your answer in arcseconds 3600 arcseconds per degree 206 000 arcseconds per radian and write the answer in the blank The angular diameter of Mars in arcseconds under the above circumstance is