Earth Rotation & RevolutionEarth Rotation & Revolution

Physical Geography 10Physical Geography 10

Earth RotationEarth Rotation The earth rotates on The earth rotates on

its axis a full 360 its axis a full 360 degrees every 24 degrees every 24 hours.hours.

This causes the This causes the difference between difference between night and day.night and day.

Earth RevolutionEarth Revolution Earth makes a Earth makes a

complete revolution complete revolution around the sun every around the sun every 365 and 1/4 days.365 and 1/4 days.

This revolution and This revolution and the tilt of the earth, the tilt of the earth, paired with the sun, paired with the sun, causes the changes causes the changes of the seasons.of the seasons.

Leap YearLeap Year We have a leap year We have a leap year

every 4 years to make every 4 years to make up for that ¼ of a day up for that ¼ of a day that isn’t accounted that isn’t accounted for on our calendar.for on our calendar.

This is to ensure that This is to ensure that our seasons match up our seasons match up with our calendar.with our calendar.

This year is a leap year!!This year is a leap year!!

What is the Relationship between What is the Relationship between Earth and the SunEarth and the Sun

The sun, in combination with earth’s axis The sun, in combination with earth’s axis is responsible for the length of day as well is responsible for the length of day as well as difference in temperature.as difference in temperature.

How Seasons OccurHow Seasons Occur The angle of the Earth's axis means that at different The angle of the Earth's axis means that at different

points on its orbit around the sun, different parts of the points on its orbit around the sun, different parts of the earth are tilted toward the sun. earth are tilted toward the sun.

The part that is tilted toward the sun is the part that is The part that is tilted toward the sun is the part that is having summer. If the northern hemisphere is tilted having summer. If the northern hemisphere is tilted toward the sun, the northern hemisphere receives the toward the sun, the northern hemisphere receives the most direct rays of the sun and it is summer in the most direct rays of the sun and it is summer in the northern hemisphere.  northern hemisphere. 

If the southern hemisphere is tilted toward the sun, the If the southern hemisphere is tilted toward the sun, the southern hemisphere receives the most direct rays of the southern hemisphere receives the most direct rays of the sun sun

Summer and Winter SolsticeSummer and Winter Solstice

Summer & Winter SolsticeSummer & Winter Solstice Tropic of Cancer – 23.5 degrees north of the Tropic of Cancer – 23.5 degrees north of the

equatorequator Tropic of Capricorn – 23.5 degrees south of the Tropic of Capricorn – 23.5 degrees south of the

equatorequator A solstice is an astronomical event that happens A solstice is an astronomical event that happens

twice a year, when the tilt of the Earth's axis is twice a year, when the tilt of the Earth's axis is most oriented toward or away from the Sun most oriented toward or away from the Sun

Winter Solstice – December 21/22Winter Solstice – December 21/22 Summer Solstice – June 20/21Summer Solstice – June 20/21

EquinoxesEquinoxesEquinoxes occur twice a year, when the tilt Equinoxes occur twice a year, when the tilt

of the Earth's axis is oriented neither from of the Earth's axis is oriented neither from nor to the Sun, causing the Sun to be nor to the Sun, causing the Sun to be located vertically above a point on the located vertically above a point on the equator.equator.

The subsolar point on a planet is where its The subsolar point on a planet is where its sun is perceived to be directly overhead sun is perceived to be directly overhead (zenith)(zenith)