Rotation

Spin or Turn on an Axis

Earth’s Axis is tilted 23.5 degrees from vertical

Vertical Axis-Like the skater

Horizontal Axis – like the log

Rotational Axis – like the Earth

What do you observeabout the angle of the tilt?

They are all the same

Earth's rotational axis points in the same direction relative to the stars, so that the

North Pole points towards the star Polaris or North Star

This constant allows sailors tonavigate at night

The Earth ContinuouslyRotates on its Axis causing

Day and Night

The Earth

Rotates around once in 24 hours

Time to rotate completely around once is called a day

The Earth Continuously Orbits

the Sun or Revolves

The time it takes for the Earth to go completely around the Sun is

called a year.

Like all planets in our solar system, the Earth is in an elliptical orbit around our Sun. In Earth's case, its

orbit is nearly circular, so that the difference between Earth's farthest point from the Sun and its closest point is very small.

It takes 365.25 rotations for the Earth to go around the Sun once.

Each 4 years, one day is added tothe month of February to make up

for the 0.25 (1/4) rotation ineach revolution around the sun.

February 29

This is called Leap Year

If you are born on February 29, whendo you have a birthday?

The Earth moves in definitepattern around the Sun

The tilt of Earth’s rotational axisand the Earth’s orbit work together

to create the seasons.

When the northern hemisphere istilted towards the sun, the

southern hemisphere is tilted away.

This is why the hemispheres have opposite seasons.

Sometimes the Earth’s axis is pointing toward the Sun and

other times the Earth’s axis is pointingaway from the sun.

Halfway in between the solstices,the Earth is neither tilted directly

towards nor directly away from the sun

These points are called equinoxes.Both hemispheres receive about

equal amounts of sunlight.

Equinoxes mark the seasonsautumn (fall)

andspring

and are a transition between summer and winter

Let’s Review

What is the turning of an object around its axis called?

A revolving

B rotating

C rolling

D ballet dancing

AXIS

What is the science term for the turning of an object around its axis called?

A revolving – IncorrectRevolving is moving around another object

B rotating – Correct

Rotating is the turning or spinning around an axis

C rolling – Incorrect

Act of causing an object to turn or rotate

What is the science term for the turning of an object around its axis called?

D dancing –Incorrect

Many dance step do not require the

rotation of the dancer’s body

How long does it take the Earth to make one rotation?

A day

B week

C month

D year

-Correct- It takes 1 day or 24 hours

-Incorrect – A week is 7 days

-Incorrect – It takes about a month for the moon to rotate

-Incorrect – It takes 365.25 rotations for a year

The constant pattern of the Earth’sorbit and its tilt causes spring to always

come before what season?

A autumn

B winter

C summer

-Incorrect – it comes beforewinter

-Incorrect – it comes beforespring

-Correct – spring is thetransition from winter to summer

What season is it in the southern hemisphere when it is winter in the

northern hemisphere?

A spring

B summer

C autumn

-Incorrect – spring is the opposite season to fall

-Correct- the south pole is tilted toward the sun

-Incorrect – autumn isopposite to the spring season

The following are constant except for:

A Earth’s Rotation

B Earth’s Orbit

C order of seasons

D weather

-Incorrect –The earth rotates continually causing day/night

-Incorrect –The earth orbits in the same path yearly

- Incorrect –The season are caused by tilt and orbit of the earth

- Correct – Weather changes continually.

What does the Earth revolve around?

A moon

B Milky Way Galaxy

C Nothing

D sun

Incorrect –The moon revolves around the Earth

-Incorrect – The Earth is part of the Solar System

-Incorrect- Observation has shown this incorrect(Everything revolves around the Earth)

– Correct – All planets and planetary systems in the Solar System revolve around the sun

During 2006, which of the following will remain constant in Texas?

A weather

B same stars seen every night

C tilt of Earth’s axis

D temperature

Incorrect – weather may change by the minute

Incorrect – Some stars are only seen during certain months

Correct – The axis will be tilted at 23.5 degrees all year

Incorrect- Temperature changes

Information and graphic sources

http://kids.msfc.nasa.gov/Earth/Seasons/Seasons.htm

http://www.windows.ucar.edu/tour/link=/image_linking.html

http://www.windows.ucar.edu/tour/link=/the_universe/uts/earth2.html

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0408/es0408page01.cfm?chapter_no=04

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