Astronomy: Earth, Moon and Stars

equinox

--when noon is directly overhead the equator--either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length

Earth in December

Noon sun is overhead at 23.5 degrees south latitude; People in the Southern Hemisphere receive the most sunlight

Earth in June

North end of the earth's axis is tilted to the sun. the noon sun is directly overhead at 23.5 degrees.

rotation

a single complete turn (axial or orbital)

orbit

an area in which something acts or operates or has power or control: "the range of a supersonic jet"

latitude

an imaginary line around the Earth parallel to the equator

WHY DOES EARTH HAVE SEASONS?

earth has seasons because its axis is tilted as it moves around the sun

WHAT CAUSES DAY AND NIGHT?

earths rotation on its axis causes day and night

Solstice

either of the two times of the year when the sun is at its greatest distance from the celestial equator

solstice

either of the two times of the year when the sun is at its greatest distance from the celestial equator

Equinox

either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length

Earth in March and September

halfway between the solstices, neither hemisphere is tilted away of to the sun; the noon sun is directly over the equator; happens over 2 days and called the equinox

autumnal equinox

occurs around september 23rd- it marks the beginning of of fall in the northern hemisphere

vernal equinox

or spring equinox occurs around march 31st and marks the beginning of spring in the northern hemisphere

axis

the center around which something rotates

example of orbit

the earth orbits around the sun on its axis

revolution

the movement of one object around another object is called revolution

astronomy

the study of the moon, stars, and other objects in space