Solar System and Planetary Science
Core concepts
Understand solar system formation from a protoplanetary disk, the frost line, accretion and differentiation, Kepler's laws applied to orbits, and the terrestrial versus giant planet dichotomy. Know orbital resonances, tidal locking, the Roche limit, impact cratering, and atmospheric escape. Be familiar with the Sun's structure and activity cycle and with comparative planetology of moons and small bodies.
Traps
Do not confuse the frost line with the habitable zone; they are different concepts. Remember that Kepler's third law in solar units gives P^2 = a^3 only for objects orbiting the Sun. Watch for sign and unit errors in escape velocity and orbital period problems. Distinguish sidereal from synodic periods.
Worked example
Find the orbital period of an asteroid at 4 AU. Using P^2 = a^3, P^2 = 64, so P = 8 years. Rule of thumb: period in years equals semimajor axis in AU raised to the 3/2 power. For a moon, use the same relation with the parent body's mass in solar units.
Rule of thumb
Escape velocity scales as the square root of mass over radius; small bodies lose atmospheres easily.