Transcript Stars and gravity - Hyde Park 3rd Grade

Chapter 15: Lesson 1- What are some patterns
that repeat every day?
Close your eyes and imagine…
You are floating in space outside the Space Shuttle. The Sun has just
risen above the curve of Earth. Look how bright the Sun is in the
blackness all around! Sunlight shimmers on the ocean far below. It’s
another amazing sunrise. What are these patterns of movement, light,
and darkness that you have seen on your space journey?
Every day there is light during the day followed by darkness at night. If
the day is sunny, you might notice shadows. Day, night, and shadows are
caused by light from the Sun and the movement of Earth.
The Sun
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The sun is a star- a giant ball of hot, glowing gases.
It is the main source of light and energy for Earth.
Earth is very small compared to the Sun. Like the Sun, Earth is
shaped like a ball. But unlike the Sun, Earth does not glow or
make its own light.
The half of Earth’s curved surface facing the Sun is lit by
sunlight. The half of Earth’s surface facing away from the Sun is
not lit by sunlight and is dark.
Day and Night
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Earth is always moving. One way it moves is that it spins
around an imaginary line called an axis.
Earth makes one complete spin on its axis, or rotation, every 24
hours. During this time, half of Earth always faces the Sun- this
half has day. The half of Earth that is not facing the Sun has
night. As Earth rotates a different part of Earth faces the Sun.
Shadows
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A shadow forms on a surface when sunlight
hits an object and is blocked.
The shadow is an area that is not getting
direct light. The shadow has about the same
shape as the object that blocks the light.
The length and direction of a shadow
depend on the time of day.
Morning and afternoon shadows are longer
than midday shadows. As the Sun moves
toward the horizon in the west, shadows
stretch toward the east. After the Sun sets,
there is no sunlight to make shadows.
The sun has just risen in the
east. In what direction do the
shadows stretch?
1. What star is a source of light and energy on Earth?
2. What is Earth’s axis?
3. What three things are needed to have a shadow?
Scientist’s Journal: “The Sun’s Position”
Illustrate the position of the Sun in the sky in the early morning,
at noon, in the afternoon, and in the late evening. Track the Sun’s
position by looking at the shadows it casts. Explain why the Sun
is only out in the daytime, and what happens to the Sun at night.
Chapter 16: Lesson 1- What are the parts
of the solar system?
Close your eyes and imagine…
Don’t look at it! The Sun has a great amount of energy. You
should never look directly at it. The Sun is the fiery center of
our solar system. This huge ball of energy holds our solar
system together. But what’s going on underneath its surface?
The solar system includes the Sun, the planets, and other
objects that travel around it. The Sun gives off energy that
moves out in all directions through space.
The Sun
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The Sun is a ball of hot, glowing gases called
plasma. It is a star.
The Sun looks larger and brighter than stars you see at night
because it is a lot closer to Earth.
How big is the Sun? Large enough to fit one million Earths
inside of it! Wider than the length of 15,000,000 football fields!
The temperature on the surface of the Sun is 5,500 degrees
Celsius. The center is millions of degrees hot. It is so hot that
gas particles that have a positive charge collide and join. This
releases a lot of energy. Energy that travels from the Sun
through space includes sunlight.
1. Why is the Sun so bright and hot?
2. Why don’t the stars at night look as bright as the Sun?
Scientist’s Journal
Draw a picture of the solar system, showing the Sun at
the center. Use pages 456-457 as a reference. Label
each planet.
Chapter 12: Lesson 4- What are star
patterns?
Think about being outside on a clear, dark night. You see
thousands of twinkling stars. Some stars are brighter than
others. Some are easier to see. But they all look so small in the
sky because they are trillions of miles away. Some of these stars
are actually larger than the Sun! The stars that are farthest
away are the dimmest and the hardest to see.
You cannot see many starts at all without certain tools to help
you. Binoculars and telescopes make studying patterns of stars
easier. They magnify objects that are far away. They make
objects look larger and easier to see. If you use a telescope, you
can see many more stars than with your eyes alone.
Binoculars and Telescopes
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Scientists use different kinds of telescopes. These telescopes
are tubes, mirrors that make light reflect, and lenses that bend
light or refract it. All these parts help bring as much light as
possible into the telescope. The result is a larger and clearer
view of objects in the sky.
Other kinds of telescopes do not collect light. They collect other
kinds of waves, such as radio waves.
A look inside the Keck
telescope in Hawaii.
The twin Keck telescopes at the W. M.
Keck Observatory in Mauna Kea, Hawaii.
1. What are two tools that can help you see stars?
2. Why do we use telescopes to look at the stars?
Scientist’s Journal
The night sky is filled with stars that vary in brightness, size,
and distance from Earth. Sometimes they make pictures and
patterns. Draw a picture of some star patterns that you have
seen. Describe, using words, what you think they look like.
Chapter 12: Lesson 2- How does force
affect motion?
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Forces act on objects to change their motions. A force can
involve two or more objects that contact each other. Other
forces can act on an object without touching it.
If the bat makes contact with
enough force, the ball’s change
in speed and direction could
take it out of the ballpark.
This shopping cart
needs little force to
start it moving, but
wait until it’s full.
The Causes of Motion
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A force is any push or pull. A force can change an object’s position or
the direction of its motion.
Most of the forces we use are contact forces. When you push or pull
an object, you must come in contact with, or touch, the object.
How much an object changes its position and speed depends on how
much force is used. The greater the force on an object, the greater
the change in motion.
She is using more force because she
is angry. Because the force is greater,
the change in motion is greater.
These people are playing tug-of-war.
Both sides are exerting force by pulling.
The rope is changing motion every time
the force is greater on one side.
Effects of Mass
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How an object moves also depends on how much mass it has.
Remember the empty grocery cart? You don’t need much force
to begin pushing it.
But as you fill it up with groceries, the cart gains more mass.
Then you have to use more force to make it move.
Effects of Friction
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While your grocery cart moves down the aisle, its wheels rub
against the floor. This causes friction. Friction is a contact force
that goes against the motion of an object. It can cause moving
objects to slow down or stop.
The amount of friction between two objects depends on their
surfaces. Pushing a grocery cart over smooth tiles in the story
is pretty easy. But you will need more force pushing the cart
across the asphalt parking lot.
Sometimes friction is a helpful force. If you’ve been skating or
sledding, you may have used friction to help you slow down.
1. What is a force?
2. What is friction?
Scientist’s Journal
Choose a sport or another activity that you enjoy doing.
Brainstorm what happens during this game and identify any
forces that they use in the sport. Write down your descriptions
and illustrate your actions. Use diagrams and labels to make you
illustrations clear.