Answers to Problem Set #1

1.  2.0x1048
2. 2.8x10-5
3.  Orbit of Pluto is 39AU = 39x1.5x1013cm = 6x1014cm. Scale factor is 3x1013 to 1.

i) human 200cm --> 200/3x1013 = 6x10-12cm
ii) Earth 6000km --> 6x108/3x1013 = 2x10-5 cm
iii) Sun 1AU --> 1.5x1013/3x1013 = 0.5cm
iv) Star 1pc --> 3x1018/3x1013 = 105 cm = 1km
v) MilkyWay 10000pc --> 3x1022/3x1013 = 109 cm = 10,000km
vi) M31 106pc --> 3x1024/3x1013 = 1011 cm = 106km
vii) Universe 5billion pc --> 1.5x1028/3x1013 = 5x1014 cm = orbit of Pluto!

4. 27km/s