# Appendix-C

## Some Astronomical Data

Some Distances from Earth
To the moon* To the sun* To the nearest star (Proxima Centauri) To the center of our galaxy To the Andromeda Galaxy To the edge of the observable universe
$$1.50 \times 10^{11}m$$ $$3.82 \times 10^8m$$ $$4.04 \times 10^{16}m$$ $$2.2 \times 10^{20} m$$ $$2.1 \times 10^{22} m$$ $$\approx 10^{26} m$$

*Mean distance.

The Sun, Earth, and the Moon
Property Unit Sun Earth Moon
Mass Kg $$1.99 \times 10^{30}$$ $$5.98 \times 10^{24}$$ $$7.36 \times 10^{22}$$
Mass Kg $$1.99 \times 10^{30}$$ $$5.98 \times 10^{24}$$ $$7.36 \times 10^{22}$$
Mass Kg $$1.99 \times 10^{30}$$ $$5.98 \times 10^{24}$$ $$7.36 \times 10^{22}$$
Mean radius m $$6.96 \times 10^{8}$$ $$6.37 \times 10^{6}$$ $$1.74 \times 10^{6}$$
Mass Kg $$1.99 \times 10^{30}$$ $$5.98 \times 10^{24}$$ $$7.36 \times 10^{22}$$
Mean density $$Kg/m^3$$ $$1410$$ $$5520$$ $$3340$$
Free-fall acceleration at the surface $$m/s^2$$ $$274$$ $$9.81$$ $$1.67$$
Free-fall acceleration at the surface km/s $$618$$ $$11.2$$ $$2.38$$
Mass Kg $$1.99 \times 10^{30}$$ $$5.98 \times 10^{24}$$ $$7.36 \times 10^{22}$$
$$Period ~of ~rotation^a$$ $$37~ d~ at~ poles^b$$ $$26~ d~ at~ equator^b$$ $$23~ h~ 56~ min$$ $$27.3~ d$$
$$Radiation~ power^c$$ Kg $$3.90 \times 10^{26}$$

$$^{a}Measured~ with ~respect~ to~ the ~distant~ stars.$$ $$^{b}The~ Sun, ~a ~ball~ of~ gas,~ does~ not~ rotate~ as~ a ~rigid~ body.$$ $$^{c}Just~ outside~ Earth’s~ atmosphere~ solar~ energy~ is~ received,~ assuming~ normal ~incidence,$$$$~at ~the~ rate~ of~ 1340~ W/m^2$$.

Some Properties of the Planets

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune $$Pluto^d$$
$$Mean~distance$$$$~from~Sun,$$$$~10^6 km$$ 57.9 108 150 228 778 1430 2870 4500 5900