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 Alliance Middle School 
Transforming Students into Career and College Leaders!

Deann Zavarelli's Multimedia Blog

Blog EntryBlog: Thursday, August 19, 2010

Satellites

After World War II ended, people found new ways to use the things developed for the war. Radar had been invented to track enemy planes. Police started using radar to watch for speeding cars. The people who report our weather used radar to track storms. For years, radar was the only thing that watched the skies.

Then President Kennedy decided that an American should land on the moon. He provided funds to NASA (National Aeronautics and Space Administration) to run the space program. In addition to space flights, NASA has put many satellites into orbit. Satellites stay at a specific height and move at a specific speed as they circle our planet. The Earth’s gravity holds them in orbit. We rely on these satellites every day.

Six kinds of satellites orbit our planet. Earth observation satellites keep track of the conditions of oceans, icebergs, volcanoes, and deserts. They also track forest fires and animal herds. Spy satellites watch military movements. Weather satellites record cloud movements and wind speeds. Global Positioning System (GPS) satellites let cars, planes, and ships know their precise position on the Earth. Astronomy satellites keep track of the sun, stars, and comets.

Communications satellites get signals from computers, telephones, and TV cameras. Then they send these signals to another computer, phone, or TV. They handle e-mails and long-distance phone calls. They let you watch what’s happening in another part of the world while it’s happening.

Out in space the sun always shines because there is no night or clouds. So satellites use solar cell power. The solar cells collect the sun’s rays and change them into electricity. Solar cells work for many years, and astronauts on the space shuttle can go up and fix them if there is a problem.

1. What is a satellite?

2. Name some different kinds of satellites.

3. Would you like to be one of the astronauts who fixes satellites out in space?

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Blog EntryBlog: Thursday, April 30, 2009

Fly Away

Airplanes fly their long-distance flights in the stratosphere, the second layer of the Earth’s atmosphere. One reason for flying in the stratosphere is the density of the air greatly decreases in this region 15 – 30 kilometers above Earth’s surface.  Airplanes tend to stay toward to lower portion of the stratosphere to take advantage of the jet stream, a fast moving air current located near the border of the troposphere.

 

 

A few characteristics of the other layers are as follows:

 

Troposphere:          location of weather patterns

                             Contains 75% of the mass of the atmosphere

 

Mesosphere:          low air density

                             rapidly decreasing temperatures

 

Thermosphere:           very thin

                                    The few molecules of air are extremely hot

 

Other than the reasons already given, why do you think airplanes fly in the stratosphere rather than in the troposphere, mesosphere or thermosphere?

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Blog EntryBlog: Tuesday, April 14, 2009

Living on a Flat Earth

Some people still believe the Earth is flat.  Members of the Flat Earth Society believe that the Earth is a disk centered at the North Pole with a 150-foot wall of ice at the edge. 


Flat Earth

 

Proponents of the flat Earth theory were challenged when photographs of a spherical Earth were taken from space and the moon.  The Society responded by claiming that the moon landings were a hoax that was staged by Hollywood.

 

The most recent president of the Flat Earth Society died in 2001 and the future of the Society remains uncertain.  You can, however, still find information supporting their theories on the internet.

 

Science, of course has much evidence to a spherical Earth.  Some of these points are presented here:

 

  • Photographs of a spherical Earth
  • Sunrise and Sunset
  • Ships on the ocean see landmarks rise or fall on the horizon
  • Seasons
  • Lunar and solar eclipses
  • Gravity

Which of science’s explanations do you feel is the strongest proof that the Earth is indeed round?  How do you think it is possible that some people still believe in a flat Earth?  At what point, if ever, does any scientific explanation become proof?

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Blog EntryBlog: Tuesday, April 14, 2009

Into the Darkness

Perspective is an amazing thing.  It is our perspective from Earth that leads to one of the greatest astronomical events the average person can see:  the solar eclipse.  

 

The sun is approximately 400 times the size of the moon.  How is it, then, that the moon can appear to completely cover the sun?  It’s like this… if you close one eye and hold your thumb up to the other one, your thumb can almost completely cover anything you choose… a house, your mom, the large plate of broccoli on your plate.  It’s just a matter of perspective.

 

The sun also happens to be approximately 400 times the distance from the Earth as the moon.  Because these ratios of distance and size are the same, the sizes of the sun and the moon from Earth are about the same.  This allows for the phenomenon of the solar eclipse.

 

There are three types of solar eclipse:

 

PARTIAL SOLAR ECLIPSE

This occurs when the moon partially covers the sun


http://www.nmm.ac.uk/upload/img_200/Partial_solar_eclipse_-_Mike_Dryland.jpg

 

TOTAL SOLAR ECLIPSE

This occurs when the moon completely covers the sun


http://www.fourmilab.ch/images/peri_apo/images/total.jpg

 

ANNULAR SOLAR ECLIPSE

This occurs when the sun and moon are exactly aligned as in a total eclipse, but the moon appears smaller than the sun, thus leaving a bright ring surrounding the outside of the moon.


http://www.wadih-ghsoubi.com/Astronomy/1/original/Annular%20Solar%20Eclipse%20at%20High%20Resolution.jpg

 

How do you think an annular solar eclipse occurs?  What must be true to give us this different perspective?  Have you ever seen an eclipse?  What was it like?

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Blog EntryBlog: Monday, March 23, 2009

Tilt-A-Whirl

The seasons we experience on Earth are the result of two phonomenon:  the revolution of the Earth around the sun, and the tilt of Earth's axis.  The Earth's axis is tilted 23.5% from vertical.  This specialized position allows for a different seasonal experience in both the northern and southern hemispheres depending upon the relation to the sun.
If you look at the diagram, when the earth is on the right of the sun (in relation to the diagram), the northern hemisphere is experiencing summer.  They experience more direct sunlight and longer days, both of which cause the heating of the land.  The opposite is of course true for southern hemisphere.  As the Earth revolves around the sun six months later, the northern hemisphere is now tilted away from the sun, experiencing winter.



Now let's take a look at the planet Uranus.  Its most unique characteristic is the tilt of its axis.  Uranus rotates almost completely on its side.  Take a look at the planet's revolution around the sun:

How would the planet of Uranus experience seasons?  If Earth was tilted in a similar matter to Uranus, what would be different?  What would the climate be like on each hemiisphere of the planet?  Would the planet be habitable?

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