space day/night and seasons. objective to model and illustrate how the tilt of the earth rotates on...
TRANSCRIPT
SPACE
Day/Night and Seasons
Objective
To model and illustrate how the tilt of the earth rotates on its axis, causing day and night and how it revolves around the Sun causing changes in the seasons
How does the Earth move?
Long ago, people thought that the Earth stood still while the Sun moved
We now know that the Earth moves around the Sun
The Earth REVOLVES around the Sun The Earth ROTATES while it revolves
around the Sun
Day and Night We have day and night
on Earth because of the EARTH’S ROTATION – the earth spinning around and around. (1670 km/hr)
Day and night
It takes 24 hours for the Earth to ROTATE once.
The Earth is kept in orbit by the force of…The Earth is kept in orbit by the force of…
GravityGravity
…and by the fact that is is moving at a high velocity
Why are there seasons?
Earth not only spins on its axis, it also revolves around the Sun
Earth’s trip around the Sun takes 365¼ days, or one year
Every 4 years, we add a Leap Day to account for the extra ¼ days
Earth's path, or orbit is shaped like an ellipse or a flattened circle
The tilt of the Earth is the reason for the seasons
The Earth is divided up into the northern hemisphere The Earth is divided up into the northern hemisphere and the southern hemisphere:and the southern hemisphere:
Equator
Northern hemisphere
Southern hemisphere
Seasons
If the Earth was perfectly balanced, as it is in this animation, we wouldn’t have different seasons and the sun would always rise and set at the same time every day.
Seasons
Every part of the Earth would receive an equal amount of sunlight as the earth rotated.
But the Earth isn’t perfectly balanced, it’s tilted on its axis…
…and it’s REVOLVING around the sun.
The tilt changes how much sunlight each part of the earth receives.
It is this tilt which makes our days longer or shorter and it’s what causes the seasons.
Seasons
The tilt does not change – it always remains pointed in the same direction
As the Earth revolves around the Sun, the tilt sometimes points toward the Sun, sometimes away from the Sun, and sometimes neither away nor toward the Sun
Summer season
In June, the North Pole tilts toward the Sun.
The northern half of Earth (Northern Hemisphere) receives more direct sunlight
Daylight hours are longer and temperatures are warmer.
June 21st - Summer Solstice
This is our summer
What season does the Southern Hemisphere
experience in June?
Winter season
In December, the North pole tilts away from the Sun.
The northern half of Earth (Northern Hemisphere) receives less direct sunlight
Daylight hours are shorter and temperatures are colder
December 21st – Winter Solstice This is our winter
What season does the Southern Hemisphere
experience in December?
Spring and Fall Seasons In March and September, neither
the top or bottom half of Earth is tilted toward the Sun
In spring and fall, the top and bottom parts of Earth (Northern and Southern hemispheres) receive the same amount of direct sunlight
The amount of daylight is close to 12 hours and the temperatures are more moderate
March 21st – Vernal Equinox September 21st – Autumnal
Equinox This is our spring and fall
What season does the Southern Hemisphere
experience in March? In September?
