now consider the statements in part a that are inferred from models. a solar model is used to calculate interior conditions based on certain known characteristics of the sun, such the sun’s total mass. how do we know the sun’s mass?

i guess it’s a and b

the only real purpose of sputnik 1 was to beat the us into space. we were getting close to launching a useful satellite, explorer 1 - which launched on january 31, 1958. the ussr had to beat that, so they launched sputnik 1 on october 4, 19