Aphelion: the name of the point farthest from the Sun on the Earth's orbital path

Aurora Australis: bright dancing lights of the Aurora caused by collisions between electrically charged particles in the magnetic poles of the Southern hemispheres

Aurora Borealis: bright dancing lights of the Aurora caused by collisions between electrically changed particles in the magnetic poles of the Northern Hemisphere

Autumnal Equinox: a day that falls on 23 September when the Sun is vertically over the Equator and the days and nights are equal

Circle of illumination: an imaginary line that demarcates the lighted portion (day) of the Earth from the darkness

Coriolis force: this force causes moving objects on the surface of the Earth to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere

Leap year: the year where one day is added to the month of February at an interval of four years

Midnight Sun: a name given to the Sun when it can be seen at midnight during the Arctic or Antarctic summers

Orbit: the curved path followed by a planet to move around another planetary object

Perihelion: the name of the point closest to the Sun on the Earth's orbital path

Revolution: motion of the Earth around the Sun

Rotation: the daily motion of the Earth on its axis

Sidereal day: the duration of 23 hours, 56 minutes and 4 seconds taken by the Earth to complete one rotation

Winter Solstice: On this day, the Sun is directly over the Tropic of Capricorn. The days are longer and the nights are shorter over the Southern Hemisphere and the opposite happens in the Northern Hemisphere