Purerehua

Science fiction

Planet Cacti        By Hannah

Deep in space 8930 million miles away from Earth's sun is a planet
called Cacti. Long green vines twist around the big kapok trees like a hug.

In the trees are big tree huts, a deep brown like the dark underearth.

Long rope bridges sway slightly in the cool breeze.

Standing happily  on the grass is a girl called Millicent.

Millicent’s  pale pink skin and thick turquoise hair shines in the sunlight.

Her rich green eyes looked silently up at the big kapok trees.

“ Your turn to give the trees acid,”  called out someone.

The type of acid that the trees need to live is hydrofluoric acid.

To get to the acid Millicent had to go down a damp, dark tunnel that leads
underground to the acid springs.

She picked up a bright red bucket and filled it with acid then walked back up
the tunnel with a bucket full of acid to tip on the strong

and sturdy roots of the kapok trees.

Millicent decided to walk down to Triton lake.

She took a narrow path down to the lake walking slowly.

Scattered over the path were cherry blossom flowers, each petal  

a different colour of the rainbow.

Millicent bent down to pick up a flower but the delicate petals

broke with the soft touch of her fingers.

As Millicent neared the lake she could hear the sploshing sound of the
waterfall hitting the saturated  grey rocks below.

Millicent looked happily at Triton lake. She saw the sun shining on it,
making the surface of the water reflect like a mirror.

“ Over here! “ shouted the boat driver.

Near the water's edge there was a dark blue boat.

The boat driver was Millicent’s friend, Harmony.

“ Where do you need to go?” asked Harmony.

“ To the crystal house on the other side of the lake,” replied Millicent.

The crystal house was where the scientists

kept the crystals they needed to unlock time travel.

At the moment they were still building the time machine.

It was a silent ride across the lake.

As they neared the dock on the other side of the lake the crystal house
came into view.

The walls were made of solid grey concrete and the roof was as orange
as a sunset.

Once they had tied the boat up at the dock they walked across the soft,
moist grass.

“ Do you have the key?” Millicent asked Harmony

“ Yes,” replied Harmony.

Millicent stood quietly as Harmony unlocked the door.

As they entered into the room the smell of the musty

air hit them in the face like a wave.

Millicent followed Harmony as they walked through the winding corridors
that led to the room where the crystals were kept.

There were four crystals, each was a different colour.  

But when the two of them walked into the room they got a huge shock.

“ The crystals are gone!” cried Millicent.

“Who could have took them,” wondered Harmony.

“I don’t know,” replied Millicent thinking hard.

“ We should look for clues in the room,” suggested Harmony.

Millicent agreed and they started hunting for clues.

“Look, over here,” shouted Millicent excitedly.

“What is it?” called Harmony.

“It looks like some sort of chest,” said Millicent.

Harmony ran over and they opened up the chest.

The soft red velvet looked as ripe as a strawberry

and caught the eyes of Millicent and Harmony.

They very carefully lifted an old crinkled map out of the chest.

The map had stains all over it making it hard for

Millicent and Harmony to read.

The map had thick black lines that twisted and entwined

with each other over the piece of paper.

There were symbols scattered over the page, some the girls knew but some looked very strange indeed.

It was difficult to study the map because the only light was

from a dim light on ceiling.   

Millicent and Harmony walked slowly out of the room and

out the front door thinking hard.

Once they were outside in the sunshine they could see

the map more clearly.

Harmony took the map from Millicent and explained that

each of the little lines stood for one step.

The map told them that they had to around Triton Lake to

where they keep submarines.

They walked around to the submarines and were greeted

by the owner of the building.

A big garage door stood in front of them and the

owner opened up and straight away,

the submarines metal was shining in the sun making it hard to see

it clearly.

They walked in and they could see the submarines clearly.

“Hi,” Harmony called out to the owner.

“Hi I’m Rusty,” replied Rusty.

“I’m Harmony and this is my friend Millicent,” Harmony said cheerfully.

“What can I do for you?” Rusty asked.

“We need to borrow a submarine,” MIllicent said kindly.  

“What for?” asked Rusty.

“ Oh, well the crystals are gone from the crystal house,

we found a map in the room and we need to go under Triton Lake,” said
Millicent out of breath.

“What kind of submarine do you need?” asked Rusty

“Just a small one,” replied Harmony.

“Ok,” Rusty said as he got a submarine ready for the girls.

Rusty took the submarine down to the water’s edge.
He told Millicent and Harmony how to work the it,
and then both the girls submerged under the water.
Once the girls were under the clear blue water they took another look
at the map. Something special about the lake is that it is like the ocean, because it has colourful coral reefs and vibrant fish.
By looking at the map Millicent and Harmony could see where they needed
to go. They needed to find cave surrounded by neon pink and purple coral.
 It took

about half and hour of searching to find the cave.
The cave had huge, stone walls, that had a thick layer of dark green
algae growing on them.

Harmony steered the submarine into the cave,
Millicent turned on the bright head lights on the front of the boat.
There were bits of discarded metal that were reflecting in the bright light.
At the back of the cave there was a big door. It opened when the submarine
came near and the Harmony steered the it into the door,
that slammed shut once they went through.

The other side of the cave had no water in it so Millicent and
Harmony got out of the submarine and started to walk around and explore.

“Is anybody here?” called out Harmony rather loud.

“I’m here,”  replied a deep voice.

“Show yourself,” said Millicent trying not to sound scared.

“It is me, Luka,” said Luka in his deep voice.

“We know that you stole the crystals,” Harmony called out bravely.

“I did indeed,” snapped back Luka.

“Why did you do it?” asked Millicent.

“I did it because I don’t want your scientists to be the first to discover time travel,
I want to,” Luka replied scornfully.

“I am also building a time machine and I need the crystals to power it,”

Millicent and Harmony were standing quiet far away from Luka so they took two
big steps forward. Both girls thought that Luka looked rather intimidating,
all his clothes were pitch black. He also had a cape that flowed slightly
as he also took some steps forward.

“Why did you steal the crystals?” asked Millicent with curiosity.

“I stole them because of something that happened a long time ago.  

“What happened?” asked Harmony.

“When I was younger I wanted to join the group of scientists in your village,
when I had joined something went missing and I got blamed and kicked of
the group,” said Luka feeling sad.

“Why did you get the blame someone could have taken it!” Millicent exclaimed.

“I know,” said Luka in a sad voice,”

“I stole the crystals to get revenge on the scientists,” Luka added scornfully.

“What if Harmony and I convinced the scientists to let you join them and
help building the time machine?”  asked Millicent.

“Why would do something like that for me?” said Luka sounding very
surprised.

“I just thought that you might want to help build the time machine that
our scientists,” began Harmony.

“I guess you could give it a try,” added Luka sounding cheerful.

All three of them hopped into the submarine (plus the crystals)
and were on their way back up to the surface.
When the submarine surfaced there was a gushing sound and lots
of clear bubbles bubbling on the emerald water. Harmony went off to
find Rusty to tell him that they were back. Millicent took Luka to the crystal
house on the boat. When they got to the crystal house Millicent lead Luka
through the door and into the lab, where the scientists were working hard.
Luka had a dark red bag that contained the crystals.

“I think you might need these,” said Luka taking they crystals carefully out
of the bag and handing them to the scientists.

“How did you get them!” cried the head scientist.

“Hey aren’t you Luka,” exclaimed someone.

“Yes it is me Luka and I took them to get revenge on you for kicking me out,”
yelled Luka.

“I was hoping that you let would let him help you build the time machine,”
Millicent said hopefully.

The scientists thought very carefully but finally gave in and let Luka join.

Two weeks later the time machine was finished and all they had to do
was put in the crystals. One by one the crystals were placed in the time
machine and it was ready to go.  

The Star Of Kazan

The Star Of Kazan By Eva Ibbotson

Do you like books that have action, adventure and mystery?
Well this is the book for you.
This book has adventure because it is interesting and exciting.
The Star Of Kazan is a fiction story.

The Star Of Kazan is set in Vienna, in a big and grand house.

This is where the professors and the maids live.
Vienna is a busy city where lots of people live.
The setting changes between the professor's house and Annikas mother’s
house.

Annika has never had a real birthday instead she has a found day.
She was found in a church on a hill and two maids took her in.
Ellie and Sigrid are maids in a grand house.
They can be stern at times but are caring and kind.
Ellie, Sigrid and Annika work for three professors, professor Julius,
professor Emil and professor Gertrude.

Annika grew up to be a good cook and maid.
Annika is a kind and caring girl, she is a good cook and never gives up.  
Her mother came to get her to take her home but then
Annika finds out the truth…

The Star Of Kazan reminds me of friendship because the
characters work together to solve the mystery of Annika’s mother.
It also reminds me of a book called The Dragonfly Pool,
also written by Eva Ibbotson which is about friendship.

The Star Of Kazan is a good book and I recommend this book for children
10-13 years old, because it might be a bit hard for children under the age of ten.
I recommend this book because it has mystery, adventure and action.
It is also interesting and exciting.

Gravity

Highlight the main ideas. Summarize these main ideas  in one or two paragraphs
Gravity is a force that attracts all objects towards each other. Gravitational attraction is
greater for more massive objects.

Gravity decreases as distance between the objects increases.

Every object in the Universe is being attracted towards every other object by the force of gravity.
Gravity keeps people on the Earth’s surface.

Gravity keeps the International Space Station in orbit around the Earth.

Gravity keeps the Moon orbiting around the Earth.

Gravity keeps the Earth orbiting around the Sun.Isaac
Newton was the first to come up with the idea that all objects are attracted towards
each other by gravity.

The Moon is 360,000 km from the Earth and only needs to be travelling at 1 km/s to stay in
orbit around the Earth. Any two masses are attracted towards each other by gravity.
This force of gravity causes the Moon to change direction to make it orbit around the Earth.
Gravity doesn’t disappear just because you are above the atmosphere.
Isaac Newton worked out that, if the distance from the centre of the Earth doubles,
gravity becomes a quarter as much as it was on the surface.
As a satellite moves around the Earth in a circular orbit,
the direction of the force of gravity is always towards the centre of the Earth.However
, if the satellite is given speed in any direction horizontal to the surface of the Earth,
it will travel further before it hits the Earth. If it is given enough speed, it will travel so far that,
as it curves towards the Earth, it will miss the Earth altogether.

Close to the Earth at an altitude of 100 km, a satellite needs to be moving at 8 kilometres
per second (28 000 km/h) to stay in orbit. Close to the Earth at an altitude of 100 km, a satellite
needs to be moving at 8 kilometres per second (28 000 km/h) to stay in orbit.
Astronauts appear to be weightless for the same reason that a person
on a trampoline feels weightless when in the air.

When does gravity decrease? Gravity decreases  as the distance between the objects increases.

When does the force of gravity become noticeable? Gravity only becomes noticeable if one or both
 of the objects has a lot of mass, such as the Earth.

Gravity disappears when you are above the atmosphere. True or False? It is true that gravity
disappears when you are above the atmosphere.

According to the text, how long does it take the International Space Station (ISS) to orbit Earth?
It takes about 90
minutes for ISS to orbit Earth.

Who first stated that all objects are attracted towards each other by gravity? Isaac Newton
first stated that all objects are attracted towards each other by gravity.

Find six words in the text that have a suffix.  Noticeable, weightless,  pulling, accepted,
horizontally, gravitation

Gravity

Gravity is a force that attracts all objects towards each other. People are attracted towards

the Earth and the Earth towards people, the Moon and the Earth are attracted towards each

other, and the Sun and the Earth are attracted towards each other. All of these attractions

are caused by gravity. Gravitational attraction is greater for more massive objects. Gravity

decreases as distance between the objects increases.

Gravity attracts all things towards each other

Every object in the Universe is being attracted towards every other object by the force of gravity. This

means that there is nowhere you can go in the Universe where gravity is not acting. Examples of gravity
in action:

Gravity holds the atmosphere in place around the Earth.

Gravity keeps people on the Earth’s surface.

Gravity keeps the International Space Station in orbit around the Earth.

Gravity keeps the Moon orbiting around the Earth.

Gravity keeps the Earth orbiting around the Sun.

Isaac Newton was the first to come up with the idea that all objects are attracted towards each other
by gravity. Even people are attracted towards each other by gravity, but this force is so small that it is
not noticeable. Gravity only becomes noticeable if one (or both) of the objects has a lot of mass, such
as the Earth. Close to the Earth at an altitude of 100 km, a satellite needs to be moving at 8 kilometres
per second (28 000 km/h) to stay in orbit. The Moon is 360,000 km from the Earth and only needs to be
travelling at 1 km/s to stay in orbit around the Earth.

There is gravity in space

Earth-Moon system and gravity

Any two masses are attracted towards each other by gravity. This force of gravity causes
the Moon to change direction to make it orbit around the Earth.

Gravity doesn’t disappear just because you are above the atmosphere. Even if an object is high above
the Earth’s atmosphere, there will still be a strong force of gravity pulling it towards the centre of the
Earth. At an altitude of 30 km, you would be above 99% of the Earth’s atmosphere. At 100 km, you
would officially be in space, yet the weight force of gravity would still be nearly the same.
You and the Earth would still be pulled together.

Isaac Newton worked out that, if the distance from the centre of the Earth doubles,
gravity becomes a quarter as much as it was on the surface.
A satellite with a mass of 1000 kg has a weight force of 9800 N at the Earth’s surface.
The radius of the Earth is about 6366 km, so at 6366 km above the Earth’s surface,
the distance from the centre of the Earth will have doubled.
The weight force pulling it towards the centre of the Earth will now only be a quarter as much
but will still be 2450 N.

So why doesn’t a 1000 kg satellite just fall back to Earth?

Sideways speed keeps satellites in orbit.

As a satellite moves around the Earth in a circular orbit, the direction of the force
of gravity is always towards the centre of the Earth.

At an altitude of 100 km, you would be so high that you would see black sky and stars
if you looked upwards. If you took a satellite to this height and released it, it would still fall towards
the Earth because the force of gravity is nearly the same as it is at the Earth’s surface.

However, if the satellite is given speed in any direction horizontal to the surface of the Earth,
it will travel further before it hits the Earth. If it is given enough speed, it will travel so far that,
as it curves towards the Earth, it will miss the Earth altogether.
At just the right speed, it will move around the Earth in a circular motion.
This type of motion and the path that a satellite moves in is called an orbit.

Close to the Earth at an altitude of 100 km, a satellite needs to be
moving at 8 kilometres per second (28 000 km/h) to stay in orbit. At higher altitudes, satellites
do not need to be travelling as fast. Television communication satellites are at a higher altitude
of 36 000 km and only need to travel at 3 km/s (11,000 km/h).

The Moon is 360,000 km from the Earth and only needs to be travelling at 1 km/s to stay in
orbit around the Earth.

If there is gravity in space, why do astronauts appear weightless?

Astronauts appear to be weightless for the same reason that a person on a trampoline
feels weightless when in the air. There is still the same amount of gravity acting, but there is
no floor pushing upwards on the astronaut, so the weight force cannot be felt.

If a person was in an elevator and the cables broke and the brakes failed (we are assured this
cannot happen), the person and the elevator would fall towards the Earth at the same rate.
The floor would not be holding the person upwards, so the person could enjoy the sensation of
weightlessness (for a brief while).

This is the same for astronauts high above the atmosphere on the International Space Station
(ISS) at an altitude of about 400 km. Gravity is still strong, but the astronaut and the ISS fall towards
the ground at the same rate. They are also both travelling horizontally at 28,000 km/h.
As they fall towards the ground, they travel so fast horizontally that they miss the Earth
altogether and orbit the Earth once every 90 minutes.

Nature of science

Science ideas change over time. Isaac Newton’s gravity-based world view has since been
superseded by Albert Einstein’s ideas that all masses distort space and time.
This highlights the fact that science is not a fixed body of knowledge. Although
Einstein’s theory is widely accepted, Newton’s law of universal gravitation is still used for
practical situations such as satellite motion.