Earth, Moon, and Sky (Astronomy)

Recall cards on how Earth's motions define the sky and our measures of time. The celestial sphere: great circles, meridians, longitude and latitude, the celestial equator and poles, declination and right ascension, and Foucault's pendulum. The seasons: Earth's 23.5-degree axial tilt, solstices and equinoxes, and the tropics and polar circles. Keeping time: sidereal versus solar days, apparent and mean solar time, standard time zones, daylight saving, and the International Date Line. The calendar: the tropical year and synodic month, the Julian and Gregorian reforms, and leap-year rules. Phases and motions of the Moon: the sidereal and synodic months, phase rise and set times, and synchronous rotation. Ocean tides: the tidal force, two bulges, spring and neap tides, and tidal friction. Finally eclipses of the Sun and Moon: umbra and penumbra, annular and total eclipses, and why they do not happen every month.