1)Flux from the sun that measured in the upper level of earth atmosphere is 1370W/m^2.%This quantitiy is named the solar constant S and is equal to pai*f(sun).Calculate the pai*F(surface of the sun) with the angular radius of the sun that measured from earth. I really don't which equation should ued to slove this question! 2)Calculate the most possible escaping velocity from our galaxy in the solar neighbourhood if the circular orbiting velocity of the sun around the galactic center is 220km/s. I know an equation that possibly relate to this question but the problem is that equation is to determine the mass of our galaxy(the Milky Way) with the known escaping velocity of the sun from the galaxy,the distance of sun from the center of the galaxy(8.5kpc) ,the mass of sun (m) and lastly the universal gravitional constant (G).By the way,I don't quiet understand the question.What does it mean of the escap[ing velocity from our galaxy in the solar neighbourhood? Can anyone explain it to me? This two question is from my tutorial work,although I had hand it to my tutor but still I don't know what is its solution.Anyway I still want to know how to solve it ,so please help me to find the solution or you can just guide me how to slove this two question.