Transcript Earth`s rotation

EDU 711
Science and Technology
Education
Trimester 1
2014
Week 5
Lecturer : Mrs. Runaaz Sharma
The Earth
and
The Solar System
Earth must be round
1.
2.
3.
The Greeks considered a sphere to be
perfect, so the earth must be a perfect
sphere
Earth was observed to cast a circular
shadow on the moon during lunar eclipse
Ships appeared to sink GRADUALLY below
the horizon as they travelled away from
observer
These were abstract evidence that led
Greeks to infer that earth had a circular
shape
The oblate Earth
• Earth not perfectly round , it is not a perfect
sphere as believed by the Greeks
• It is an oblate shape
• It is flattened at the poles and has an equatorial
bulge
• For example: a water filled round balloon resting on a table
So what provided the concrete
evidence of an oblate earth ?
Artificial satellites travelling around
the earth has sent pictures of earth
from space
▫ Gives precise size and shape of earth
Motions of earth
There are seven different types of motion (see
Tillery, Enger and Ross, 2011)
Three of the motions are important to
understand as they are independent of the
motions of the sun and the galaxy.
1. A yearly revolution around the sun
2. A daily rotation on its axis (referred to as
spinning)
3. A slow clockwise wobble on its axis due to its
oblate shape
Motions of the Earth
ROTATION
REVOLUATION
Earth rotates on its axis as it revolves around
the Sun.
The earth’s rotation on its axis (spin )
Earth’s rotation
 The Earth rotates once in twenty-four hours.
• The Earth’s rotation is responsible for the daily
cycles of day and night.
• At any one moment in time, one half of the
Earth is in sunlight, while the other half is in
darkness. When the earth rotates we get day
and night.
▫ The part of the earth facing the direct sunlight has
a day
▫ The part of the earth not in the direct path of the
sunlight has a night
TIME
• Fleming proposed that the globe be divided
into 24 time zones, each 15 degrees of
longitude in width.
• Since the world rotates once every 24 hours on
its axis and there are 360 degrees of longitude,
each hour of Earth rotation represents 15
degrees of longitude
360 ÷ 15 = 24
• Always calculated from Greenwich ,0 degrees
longitude
• EAST - INCREASE
Time is forward to all places
to the east
• WEST- LESS
• Time is backward
to all places to the
west
Earth’s Revolution
• The movement of the Earth around the sun.
• It revolves around the sun in an elliptical orbit
Revolution of the Earth
It takes 365 days and a
¼ days to complete one
revolution.
The distance between
the earth and the sun
changes
due
to
revolution.
This change of distance
also causes change in
seasons.
Equinox and Solstice
The Solar System
How many planets are there in the
solar system ?
• 8 planets
• 5 dwarf planets
(there is an ongoing debate as to whether the dwarf
planets should be counted or not)
Why are some planets called dwarf ?
The Inner planets in order
from the sun.
• Mercury
• Venus
• Earth
• Mars
All inner planets
are:
• Smaller and warmer
• Have rocky surfaces
• Have no more than 2 moons
The Outer Planets in order from
the sun.
• Jupiter
• Saturn
• Uranus
• Neptune
All outer planets
are:
Made mostly of frozen gas
Larger and colder
Have more than 2 moons
Asteroid
• A large piece of rock or metal that
orbits the sun.
- Some can be very large
- Others are as small
as a grain of sand.
Different asteroid belts in our solar
system
What are comets?
• Comets are lumps of ice and dust that
periodically come into the center of the solar
system from somewhere in its outer reaches
• Some comets make repeated trips.
• When comets get close enough to the Sun, heat
makes them start to evaporate.
• Jets of gas and dust form long tails that we can
see from Earth. These tails can sometimes be
millions of miles long.
Comets
Comets
Technologies used in space explorations
1. Telescopes
• A telescope - is an instrument
people use to observe distant objects.
It magnifies objects so that they are
easier for us to see.
There are different types of telescopes:
• Radio telescopes - use radio waves in order to produce
an image.
• Optical telescope - There are two main
kinds of optical telescopes
Kinds of optical telescopes
There are two kinds :
1. Reflecting telescopes - use curved mirrors to magnify
objects.
•
•
Hubble space telescope was first sent into space in 1990.
The Hubble Space Telescope has an advantage over landbased telescopes. Because it is located in space, the
pictures it produces are not affected by Earth’s
atmosphere. The pictures are brighter and clearer.
2. Refracting telescopes - use lenses (like in
eyeglasses) to magnify objects.
• The first refracting telescope was built in 1609
by Galileo Galilei.
Galileo could see
mountains on the moon, four of Jupiter’s
moons,
Saturn’s
rings,
and
sunspots.
Images from Hubble telescope
•
An image taken by the refurbished Hubble Space Telescope shows a panoramic view of a colorful assortment
of 100,000 stars residing in the crowded core of a giant star cluster
Source: : http://blogs.sacbee.com/photos/2009/09/hubble-telescopes-latest-image.html#storylink=cpy
An image taken by the refurbished Hubble Space Telescope, shows the planet Jupiter.
Image released by NASA on Wednesday, Sept. 9. NASA
Source : http://blogs.sacbee.com/photos/2009/09/hubble-telescopes-latestimage.html#storylink=cpy
2.Crewed Missions
• Another way to study the solar system is to
actually go there on a trip called a crewed
mission.
▫ A space shuttle can bring astronauts and their
tools into space to perform experiments, launch
satellites, and make observations.
• In 1957, the first living creature sent into space
was a dog named Laika! Scientists sent a dog into
space first because they wanted to be sure that
living creatures could survive in space before
sending a human.
Source: http://www.independent.co.uk/life-style/history/to-outer-space-andback-to-earth-again-2266699.html?action=gallery&ino=1
• In 1967, the first person was sent into space,
Yuri Gagarin, from Russia. Since then there
have been many crewed missions to space. One
of the most famous crewed missions occurred in
1969, when Americans Neil Armstrong and
Edwin “Buzz” Aldrin walked on the moon.
Yuri Gagarin
3. Space Probes
• A space probe -is an instrument used to
• explore places and objects in space.
Space probes can:
• Carry cameras, instruments, and other tools
• Perform fly-by missions
• Land on planets and moons
• Collect samples, test for water, and take pictures
Famous space probes:
• Galileo - sent to Jupiter in 1989, arrived in 1995
• Sojourner - sent to Mars in 1997, arrived in 1997
• Cassini-Huygens - sent to Saturn in 1997, arrived in
2004
• New Horizons - sent to Pluto in 2006, is scheduled to
arrive in 2015
What are the technology implications ?
• Technology can be used to complement many
space activities:
▫ about sundials , shadow stick
• Space explorations open up possibilities for
technological activities related to rockets and
vehicles for lunar and space travel
▫
▫
▫
▫
preparing models of the solar system
devising a system that makes use of the suns energy
designing a solar still
designing and producing a play or video based on TV
episodes on space series
(Skamp, 2004: 419)
Model for seasons and phases of the
moon
Solar Cooker
Solar Still
Sundial
Conclusion
• Science ideas / and theories about the universe are
based on inference made from many strong
observations. Therefore ,is subject to change given
further evidence
• So as teachers we need to keep reading on this topic
to keep updated.
• Use of educational technologies in particular
advanced technologies can assist greatly in teaching
about earth and the solar system
Tutorial questions
1. Explain why sundial time is often different than the
time on the clock?
2. Explain the reasons using the earth motions as
reference for the following :
▫ Seasons
▫ Time
3. Discuss some teaching ideas that teachers can use to
teach about earth and the solar system ?
4. Explain why use of advance technology is important in
teaching about the earth and the solar system?
5. Study the primary curriculum and identify some design
projects teachers can use in this topic?
6. Explain the terms equinox and solstice ?
Example of interactive application
using Microsoft PPT
1. The Earth spinning on its axis.
Rotation
Revolution
2. Going around a larger body.
Rotation
Revolution
Revolution
3. 24 hours.
Rotation
Revolution
4. Causes the Earth’s seasons.
Rotation
Revolution
5. Creates a year.
Rotation
Revolution
6. The moon going around Earth.
Rotation
Revolution
Identify the motion being shown in each of these
pictures. Each team must write their answers for each
figure in the form of a question.
Figure #1
Rotation
Planet
Figure #2
Rotation
Revolution
Earth
Revolution
References
• Skamp,K. (2004).Teaching Primary Science Constructively.
Nelson: Thomson.pp 419
• Tillery, B.W., & Enger,E.D., & Ross, F.C. (2011). Integrated
Science. (5th ed.). McGraw- Hill Companies Inc. New York.
(pp 263 - 274), (pg 306 - 322) and (283- 299).
• Images:http://www.google.com.fj/url?sa=i&rct=j&q=&esrc=s
&source=images&cd=&cad=rja&docid=yg-vDKWxNiSuM&tbnid=ghJsNnkcvUwrdM:&ved=0CAMQjhw&
url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D
R0ieYWDsQSk&ei=UfUDU7mqCMSOkAWDloEg&bvm=bv.6
1535280,d.dGI&psig=AFQjCNG5z7P4KQtkho9GDOvzQ_7D_O2rQ&ust=1392854590161782
Suggested websites
• http://spaceflight.nasa.gov/home/index.html
• http://www.learner.org/jnorth/tm/mclass/season_simulator.html
• http://muse.tau.ac.il/museum/galileo/heliocentric.htmlSlide 7