mc

• terrestrial motion - pertains to the movement of any object on earth
• celestial motion - refers to that of any object beyond earth
• natural motion - is determined by the nature of an object's composition
• violent motion - happens when an object is acted upon by any external force
• alteration - refers to a type of motion that describes qualitative change
• celestial equator - the projecton on earth's equator in the celestial sphere
• ecliptic - the sun's apparent path through the celestial sphere
• equinox - happens when the sun's position in the ecliptic intersects with the celestial equator
• solstice - happens when the sun's position in the ecliptic reaches it northernmost or southernmost point
• obliquity of the ecliptic - refers to the angle of inclination of earth's equator with respect to the orbital plane
• diurnal motion - daily rising and setting of the sun
• annual motion - refers to the apparent shift in location of the stars
• precession of the equinoxes - an ancient term for the gradual change in the orientation of earth's axis
• sidereal year - refers to the time it takes for the sun to return to the same point relative to the fixed stars
• tropical year - the time it takes for the sun to return to an equinox
• general precession - combination of planetary precession and lunisolar precession
• homocentric - the celestial spheres share one common center
• deferent - refers to a circular path in which planet moves around earth
• lunar craters - darks spots of the moon
• cosmica sidera - four celestial bodies surrounding jupiter
• sunspots - dark spots on the sun's surface
• supernova - refers to a huge burst of energy from an explosion of a supergiant star