Transcript Rotational Axis

Rotation
Spin or Turn on an Axis
Vertical AxisLike the skater
Horizontal Axis –
like the log
Rotational Axis –
like the Earth
Earth’s Axis is tilted 23.5 degrees
from vertical
What do you observe
about the angle of the tilt?
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 to
navigate at night
The Earth Continuously
Rotates 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 to
the month of February to make up
for the 0.25 (1/4) rotation in
each revolution around the sun.
February 29
This is called Leap Year
If you are born on February 29, when
do you have a birthday?
The Earth moves in definite
pattern around the Sun
The tilt of Earth’s rotational axis
and the Earth’s orbit work together
to create the seasons.
When the northern hemisphere is
tilted 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 pointing
away 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 seasons
autumn (fall)
and
spring
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?
B rotating – Correct
Rotating is the turning or
spinning around an axis
A revolving – Incorrect
Revolving is moving around another
object
What is the science term for the turning
of an object around its axis called?
C
rolling – Incorrect
Act of causing an object to turn or rotate
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?
-Correct- It takes 1 day
or 24 hours
A
day
B
week
C
month -Incorrect – It takes about a
month for the moon to rotate
D
year
-Incorrect – A week is 7 days
-Incorrect – It takes 365.25
rotations for a year
The constant pattern of the Earth’s
orbit and its tilt causes spring to always
come before what season?
A
autumn
-Incorrect – it comes before
winter
B
winter
-Incorrect – it comes before
spring
C
summer -Correct – spring is the
transition from winter to summer
What season is it in the southern
hemisphere when it is winter in the
northern hemisphere?
A
spring -Incorrect – spring is the
opposite season to fall
B
summer -Correct- the south pole is
tilted toward the sun
C
autumn
-Incorrect – autumn is
opposite to the spring season
The following are constant except for:
A
Earth’s Rotation
-Incorrect –
The earth rotates continually causing day/night
B
C
Earth’s Orbit
-Incorrect –
The earth orbits in the same path yearly
order of seasons - Incorrect –
The season are caused by tilt and orbit of the earth
D
weather
- Correct –
Weather changes continually.
What does the Earth revolve around?
A
moon Incorrect –
The moon revolves around the Earth
B
Milky Way Galaxy
-Incorrect –
The Earth is part of the Solar System
C
Nothing -Incorrect(Everything revolves around the Earth)
Observation has shown this incorrect
D
sun – 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
Incorrect –
weather may change by the minute
B
same stars seen every night
Incorrect –
Some stars are only seen during certain months
C
tilt of Earth’s axis Correct –
The axis will be tilted at 23.5 degrees all year
D
temperature Incorrect- Temperature changes
Information and graphic sources
Microsoft Office Online
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