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