The planets

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Mecury

• always 30$°$ from the sun
• strong tidal forces, permanent prolate tidal bulge
• sidereal rotation $P_{rot}=58.65d$
• $P_{orb}=87.97$
• Orbit is tidally locked at perihelion

Venus

• Retrograde Motion
• atmosphere \begin{list}{-}{}
• Clouds are sulfuric acid
• $\sim$ 96.5\ co2% and $\sim$ 3.5% N2
• Very strong greenhouses

\item Earths liquid water ocean dissolves co2 \item runaway greenhouse \end{list}

Earth

• Temperature and pressure on earth allow significant qualities of gas, liquid, and solid water. Not true for Venus or Mars

Mars

• $\alpha =1.52$AU
• $P_{sidereal}=1.88$
• $24h40m$
• Atmosphere \begin{list}{-}{}
• Pressure $\sim .006$atm (earth)
• 95% $C{O}_2$
• UV photodissociastes $H_{2}O$, the oxygen oxidizes iron in soil

\item Seasons caused by obliquity \item polar caps of $C{O}_2$ form and melt in winter and summer \end{list}

Jupiter and Saturn

• they are in hydrostatic equilibrium
• $\frac{dP}{dr}=-\frac{G{M}_r\varphi }{r^2}$
• $M_r$ is the mass within radius $r$ assuming constant density $\varphi$
• ${\int }_{P_c}^{0}dP=\frac{4\pi }{3}{\varphi }^{2}G{\int }_0^R$
• solving shows that there must be very high pressures in centers of Jovian planets
• Metallic hydrogen is a conductor
• convection + rotation in a conducting fluid produce magnetic dynamos and magnetic fields

energy deficit for jupiter

• Jupiter’s luminosity is twice its rate of solar irradiation from the sun
• Consider gravitational potential energy of a shell of thickness
• extra energy comes from the radius shrinking

Fast rotation

• Polar diamter of jupiter is 6.5 shorter thne equatorial bulge
• saturn is 10% shorter than equatorial diam

rings

• all Jovian planets have rings; Saturn are the most prominent
• tidally disrupted satellite inside Roche limit
• internal structures caused by orbital resonances