La Tierra y la Luna

La Tierra


La Tierra es Redonda

Un concepto que hoy en día nos parece tan evidente como el de que la Tierra es redonde (o mejor dicho esférica) no siempre ha sido tan evidente. Antiguamente se pensaba que la Tierra era plana y que llegaba un punto en el que el agua de los océanos se derramaba por los lados en forma de gigantes e infinitas cataratas.

La gran pregunta que hay que hacerse es la siguiente ¿Quién fue o quienes fueron los que realmente se atrevieron a decir que la Tierra era plana? Lo que está claro es que las primeras evidencias de una Tierra esférica provienen de la antigua Grecia. Muchos filósofos, científicos e intelectuales de la antigua Grecia han sido en algún momento relacionados con este  concepto:

Hay quien dice que el primero que habló sobre este concepto de una Tierra esférica fue el filósofo griego Pitágoras (Siglo VI a.C.) aunque no está muy claro que así fuera. Esto se basa en que este concepto era conocido por dos filósofos de la "escuela pitagórica" como Parménides o Empédocles (Siglo V a.C.).

También se sabe que más tarde otros conocidos filósofos hablaron de este concepto: Platón (427-347 a.C.) enseñaba que la Tierra era una esfera aunque no ofreció ninguna justificación. Así en su obra El Timeo (en torno al año 360 a.C.) se lee que "(El Creador) hizo el mundo en forma de globo, redondo, de por sí la más perfecta de todas las figuras". También Aristóteles (384-322 a.C.) observó que había estrellas que se veían desde un sitio y no desde otro. Por ello consideró la forma esférica de una Tierra de un tamaño no muy grande. Incluso dio una serie de argumentos físicos y basados en observaciones para sustentar esta idea de que la Tierra es esférica.

En fin, el caso es que sólo eran ideas que no fueron demostradas hasta que una expedición consiguió rodear por primera vez nuestro planeta. Realmente no está registrado en ningún lado cómo la esfericidad de la Tierra fue descubierta.

La Luna

La Luna es el único satélite natural alrededor de nuestro planeta Tierra. Gira respecto a la Tierra de forma que siempre muestra la misma cara, en la cual se pueden observar muchos "mares lunares" de origen volcánico entre montañas antiguas.

La Luna es considerado como el quinto satélite más grande del Sistema Solar y después del satélite de Júpiter llamado Ío, es el segundo satélite más denso.

Aunque desde la Tierra la veamos muy luminosa y brillante, en realidad es muy oscura. De hecho tampoco es uno de los astros que mejor reflejen el Sol (tiene una capacidad de reflejar la luz similar a la del carbón).

La influencia gravitacional de la Luna en nuestro planeta Tierra produce las mareas y la distancia tan "escasa" que los separa (en torno a treinta veces el diámetro de la Tierra), hace que se vea en el cielo con el mismo tamaño que el Sol y permite que la Luna cubra exactamente al Sol durante los eclipses solares.

El poder visitar y habitar La Luna siempre ha sido una obsesión del ser humano. De hecho, La Luna es el único cuerpo celeste que los humanos hemos conseguido pisar. Y no fue hasta 1969 cuando la tripulación de la expedición norteamericana del Apolo 11 consiguió pisar suelo lunar. Sin embargo, el primer intento de alcanzar la Luna lo realizó la antigua Unión Soviética con su programa llamado programa Luna y con una nave espacial no tripulada.

Gracias a algunas rocas traídas de esas expediciones a la Luna, se ha podido investigar sobre los posibles orígenes de la Luna (se cree que se formó hace 4500 millones de años después de un gran impacto).

También podemos obtener más información en el siguiente video sobre la Luna: https://www.youtube.com/watch?v=D_15||SUm6Q

Las fases lunares

La Luna como satélite que es, gira alrededor de la Tierra. Este giro dura en torno a 28 días (4 semanas) y durante este trayecto puede presentar diferentes aspectos o formas según sea su posición con respecto al Sol. Cuando la Luna está entre la Tierra y el Sol, tiene orientada hacia la Tierra su cara no iluminada (a esta fase se le llama novilunio o Luna nueva). Una semana más tarde, la Luna ha dado un cuarto de vuelta y presenta media cara iluminada (fase conocida como cuarto creciente). Otra semana más y la Luna ocupa una posición alineada con el Sol y la Tierra, por lo cual desde la Tierra se aprecia toda la cara iluminada ( a esta fase se le conoce como Plenilunio o Luna llena). Una semana más tarde se vuelve a ver media cara iluminada (lo que se conoce como cuarto menguante). Transcurridas unas cuatro semanas estamos otra vez en la fase de novilunio.

Aquí os dejo un video sobre la luna y su rotación:

https://www.youtube.com/watch?v=DEGpv9T7cC4

Y aquí hay otro video que habla sobre las fases de la luna y los eclipses:

The Light

Light

Light moves in a straight line. It goes straight to an object.
Light moves very fast. The speed of the light is considered around 300,000 Km/s (three hundred thousand kilometers per second).

Light is responsible for the sense of sight. It is known as Visible light. Visible light is emitted and absorbed in tiny "packets" called photons.

Some objects do no let light through. When light cannot travel through an object, appears a shadow.


The shadow of an object always appears at the other side of the source of light. Look at the pictures: Where is the focus of the light in each picture?

 


COLOURS

The light we get from the Sun is called white light.

White light is a mixture of seven colours: red, orange, yellow, green, blue, indigo and violet.
We can see all these colours in the rainbow (when the light travels through the raindrops) or when the light passes trhough a prism.

Watch this video:



We can classify objects depending on how much light can pass through them:

• Transparent objects: clear glass allow light to pass through.
• Translucent objects: allow some light to pass through and we cannot see objects behind them very clearly. Some liquids ar translucent.
• Opaque objects: These objects do not allow light to pass through such as cardboard or wood.

Have a look to this video: 

Some objects can give light (they are a source of light). We call them luminous bodies. We can distinguish between Natural luminous bodies and Artificial luminous bodies (made by humans).

Non-luminous objects cannot produce light Most of them only reflects the light that reaches them.

Different Ecosystems

Differences between an Ecosystem and a Biome



        An Ecosystem describes a specific area where the organisms (living things and non-living things) interact together as a unit. It can be very small like a swiming pool with water or it can be so big as a desert or an ocean. Each ecosystem is different and each each individual plant, animal or non-living thing is important to the rest of the components of this ecosystem.

• All living organisms need millions of other living organisms to survive. The sun, soil, water, air, minerals, rocks, animals and plants need each others.

• The sun provides the energy needed by ecosystems. Plants take this energy and use photosynthesis to make their own food (energy). Nutrients in the soil, the air, and water also play a part in keeping an ecosystem thriving and in balance. 

       A Biome is the name to describe a large group of similar ecosystems. Biomes have similar weather, rainfall, animals, and plants. There are a number of biomes on planet Earth. See the map of the world biomes below.









Now we are going to talk about them. Click on the biomes below to learn more about each one.

Land Biomes
Desert
Grasslands
Savanna
Tundra
Tropical Rainforest
Temperate Forest
Taiga Forest

Aquatic Biomes
Marine
Freshwater
Coral Reef

Humans and the Ecosystem 

Humans have adversely affected many ecosystems and biomes throughout the world. Cutting down trees, developing land, growing crops, burning fossil fuels, overfishing, and overhunting are just some of the ways that we have upset the balance of nature.





Information obtained from http://www.ducksters.com/science/ecosystems/world_biomes.php

Ecosystems

What is an ecosystem?

An ecosystem is a place and the living things that live there.

An ecosystem is made up by:

• Living things: They born, grow, eat, breathe and reproduce.  We have two big groups: Plants and Animals.
• Non-living things: do not eat or grow. They are for example: air, water, soil, minerals...

 Audio
 (If you cannot open the sound file, download the VLC program here: download VLC )

There are big ecosystems like the savannah, the desert or the oceans. Even the Earth (our planet) can be considered the biggest ecosystem.






Other ecosystems are small like a pond or a river.




An ecosystem that we can find near of us is the Forest ecosystem: In a forest, there are plants like trees, bushes and grasses. There are insects and other kind of invertebrates animals such as beetles, ladybirds, butterflies, worms or spiders. There are vertebrates animals like squirrels, birds, mice, deers, owls or wolves.

 Other very common Ecosystem is the Sea: It is the biggest ecosystem of the Earth. In the sea, there are plants like seaweeds, invertebrates animals such as jelly fishes, crubs, mussels and octopuses; even vertebrates animals like fishes, dolphins and whales. Almost all of them live in the high sea. In the deep sea there are very little food, so very few animals can live there.





            In an ecosystem is very important the FOOD CHAIN or FOOD WEB: It is when an animal eat other animals or plants and it is eaten by other animals bigger. For example: herbivores animals (like rabbits) eat plants, carnivores animals (like eagles or hawks) eat this herbivores animals (rabbits) and some of these carnivores animals are eaten by other carnivores bigger.






The best video filmed by a tourist:

The same video translated to spanish

Activity to use in class with the Interactive Digital Board (IWB)

Here there is an activity for teachers to use in Science class with the Interactive WhiteBoard, as well known as Interactive Digital Board. This activity is created by two teachers at CRP Sant Martí, Barcelona during year 2012-13. To download the file, click the picture or the link below.

https://www.dropbox.com/s/8gthhw8nhhplclu/Ecosystems_science_project.notebook

Videos to watch and learn.

Now, you can watch some videos about it to obtain more information.

Video about ecosystems and food chains.

Video about components of the ECOSYSTEMS

http://www.youtube.com/watch?v=MWPj2IkeklI

Here you are a video in Spanish.

in Spanish: http://www.youtube.com/watch?v=tPFGdTE_nas

La Tierra y el Universo (Ampliación)

LA TIERRA es nuestro planeta conocido como "El Planeta Azul".

Aquí os dejo un enlace para ver un vídeo sobre la Tierra y de qué está compuesta:

La Tierra y su composición



¿Cómo se formó la Tierra? aquí hay un video para aprender un poco sobre ello.

Así se hizo la Tierra. El nacimiento de la Tierra. (youtube)

¿Y el Universo? aquí hay un video sobre El Big Bang.

La historia del Universo: El Bing Bang

Reportaje sobre el Big Bang de National Geographic.

Ciencia al Desnudo - Big Bang (National Geographic)

Video sobre una de las curiosidades del universo: LOS AGUJEROS NEGROS.

AGUJEROS NEGROS

The Universe, The Milky Way and The Solar System

The Universe

The universe is a name for all matter and energy. It includes The Earth (our planet), other planets, stars, satellites and comets, the Solar System and other galaxies. It has other names such as the cosmos or the world.

The Universe is full of astronomical bodies. We can classify them in two big groups:

• luminous astronomical bodies: They give off light and heat. For example: Stars. 
• non-luminous astronomical bodies: They don't give off light; they only reflect the light from the stars. For example: planets, satellites and comets reflect light from the Sun and other stars.  

Sometimes people name the Universe like Solar System or The Milky Way, but they are not the same.

Universe, The Milky Way and The Solar System.

Do you understand the difference between them?   No?
Ok. We will try to explain the differences:

The Earth is our planet. It is one of the planets of our Solar System; The Solar System is a small part of our Galaxy (the Milky Way); and the Milky Way is a Galaxy of the Universe.

Our Earth orbits the Sun in our Solar System. Our Sun is one star among the billions in the Milky Way Galaxy. Our Milky Way Galaxy is one among the billions of galaxies in our Universe. You are unique in the Universe!

Do you understand it now? Not yet? Ok, we will learn more...


The Universe is made up of billions of galaxies. NASA's telescopes allow us to study these galaxies in detail.

The Hubble Space Telescope made the one of the most beautiful images of the universe called the Hubble Extreme Deep Field. Soon the James Webb Space Telescope will be exploring galaxies forming at teh very beginning of the universe.

This is the famouse Hubble Extreme Deep Field made by the NASA. Every spot is a galaxy.

One of these Galaxies is The Milky Way (Vía Láctea in Spanish). It is made up of between 200 and 400 billion stars. The Milky Way is a big galaxy but there are some galaxies much bigger, like our neighbour Andromeda Galaxy (Galaxia de Andromeda in Spanish).

One of these hundreds of billions of stars is our Sun. the Sun is the centre of our Solar System.

The Solar System is a part of the Milky Way. It consists of: the Sun and other astronomical bodies like planets (including the Earth), asteroids and comets that orbits the Sun and other like satellites that orbit the planets.
For example: The Earth is a planet that orbits the Sun, and the Moon is a satellite that orbits the Earth.

Here, there is a picture of our galaxy, The Milky Way. Can you find the Solar System?

What we used to study is our Solar System, so here there are some basic notions about it:

There are eight planets orbiting the Sun:

• Mercury is the closest planet to the Sun and the smallest planet of the Solar System.
• Venus is a rocky planet and teh second closest planet to the Sun.
• The Earth is our planet. It is called the Blue Planet because it has a lot of water.
• Mars is a rocky planet and it is called "The Red Planet" because it has a lot of iron oxide.
• Jupiter is the largest planet in the Solar System. It is a gaseous planet.
• Saturn is the second larges planet in the Solar System. It is a gaseous planet and it is famous by its ring system, that consists of nine continuous main rings and three discontinuous arcs, composed mostly of ice particles with rocks and dust.
• Uranus is the seventh planet from the sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System.
• Neptune: is the farthest planet from the Sun. It is a gaseous planet and it is the fourth-largest planet by diameter and the third-largest by mass.

Pluto was considered a planet between 1845 and 2006. In 2006 Pluto was not considered a planet anymore. However, in the 19th Century (between 1807 and 1845) some astronomical bodies such as Ceres, Pallas and Vesta were considered as planets.

Here you can find a song about the planets for children. It is very easy to understand.

The planet song for children

But if you want a song with more rythm, you can watch this video of Bemular.

The Planets Song - Bemular 

In August 2006, the IAU (International Astronomical Union) established the definition of planet.

This definition of planet states that, in the Solar System, a planet is a celestial body that:

• Is in orbit around the Sun
• Has a nearly round shape.
• and has "cleared the neighbourhood" around its orbit.

Pluto was considered a member o a new class of planets, named dwarf planets, created, initially containing three objects: Ceres, Pluto and Eris.

Between 1807 and 1845 the list of planets was: 

1. Mercury
2. Venus
3. Earth
4. Mars
5. Vesta
6. Juno
7. Ceres
8. Pallas
9. Jupiter
10. Saturn
11. Uranus

Then, between 1854 and 1930 and from 2006 to now, the list of planets is:

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune

Here there is a picture about our Solar System:

Here you are a short video about The History of the Universe in only 10 minutes.

The History of Universe in 10 minutes

A longer video about the birth of our Planet: The Earth

The Birth of Planet Earth

Minerals and rocks: Ampliación en Español

Más información sobre Minerales y rocas (en Español)

Ejercicio Ampliación sobre el Ciclo de las rocas realizada por la junta de Comunicadades de Castilla y León

http://recursos.crfptic.es/ambientech/indice_asignatura.swf

Vídeo sobre minerales y rocas donde explica cómo se clasifican:

Vídeo curioso sobre cómo se extrae el oro:

Documental sobre la utilidad de las Rocas y los minerales (www.Youtube.com):

Video sobre Minerales y la importancia económica que tienen

Minerals and Rocks

Minerals are natural materials.
They can be part of rocks, animal bones and shells.  

There are minerals on the Earth's surface and under the ground.
Minerals have different:

• Shape: Some minerals have a regular hsaape, like pyrite. Others have an irregular shape, like turquoise or quartz.
• Colour: Each mineral has a typical colour or colours.
• Malachite is green, marble is white and others can be severeal colours, like quart.
• Shiny or dull: Some minerals are shiny, like pyrite. Others are dull, like chalk.
• Hard or soft (hardness): Diamond is the hardest mineral. Gypsum is the softest.

There is a scale of hardness for minerals called the Mohs scale.

Some examples of classification of minerals are: 

• Gypsum is a white or red mineral. It is dull and soft. 

• Pyrite is a cube shaped mineral. It is grey and shiny.

We use minerals like gypsum to build buildings.

We use minerals like diamonds, gold or silver  to make jewellery.




Pyrite is known as fool's gold because it looks like real gold.





Minerals are very useful in everyday life.
If tou look around your home and on the street you can find minerals everywhere.
There are minerals in your bathroom (talcum powder), in your pencil (graphite), we can find gold, silver and quartz in our digital watches, rubies, emeralds and diamonds in our jewellery. We use gypsum to make plaster casts for broken bones and copper to make pans, electric cables and coins.

Rocks are materials made up of minerals.
They form the solid part of the Earth.
Some examples of rocks are clay, marble, clay and granite

Some rocks are made up on fonly one mineral. For example, marble is made up of calcite.

Many rocks are made up of a mixture of minerals. For example, granite is made up of feldspar, mica and quartz.

Rocks can be hard, like marble, or soft, like clay.

They can be different colours: coal is black, Marble can be several different colours. Petroleum is a liquid rock


We dig mines to obtain rocks that are under the ground. For example, coal.
We dig quarries to obtain rocks, that are on the surface. For example, granite.

Some kind of rocks (like slate, marble and granite) are used for building (in constructions). For example, granite is used to make walls. Clay is used to make bricks. Slate is used to make roof tiles.

Other materials, like coal or petroleum, is used for fuel. When they burn they give off heat.

In industry. Petroleum is transformed into plastics, paint and fertilizers.
For decoration. Marble is used to make statues and ornaments.
For example the famous statue David of Michelangelo Buonarotti is made up of a huge block of marble.






Video A brief Introduction to minerals

http://www.youtube.com/watch?v=8a7p1NFn64s

Video Erase una vez el Hombre: Nace la Tierra.

http://www.youtube.com/watch?v=qOFB3JfYq5c

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing

The way animals move.

Another classification of animals could be by the way they move. Animals can:

• Walk: 
• Almost all mammals move walking. We have to except some aquatic mammals, like dolphins, sharks or whales; and the bat, maybe the only mammal who can fly.
• Some amphibians
• Some birds.

• Fly:
• Almost all birds move flying. Some birds, as for instance the penguin cannot fly. We have mentioned before the bat (a mammal).

• Swim:
• All fishes move swimming.
• Some aquatic mammals move swimming.
• Some anphibians can swim. 

• Crawl along the ground:
• Some anphibians move crawling along the ground. They do not have legs

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing 

Herbivores, Carnivores and Omnivores

All animals need to eat food. We can classify animals, according to the food they eat, into three groups:

Herbivores: These animals eat plants. They eat different parts of plants: roots, leaves and fruits. They have special teeth to help them cut and cheww plants. For example: Deer, cows, horses, ponnies and rabbits are herbivores.

Carnivores: These animals eat other animals. They hunt and eat meat. They have sharp teeth. They have excellent eyesight. For example: Foxes, eagles, pumas and lions are carnivores.

Omnivores: These animals eat plants and other animals. Bears and chimpanzees are omnivores.

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing 

Viviparous vs Oviparous

One way for classificating animals can be the way they are born. In that way, we can classify animals into two groups:

• Viviparous: They are born from their mother's womb. 

• Oviparous: They are born from eggs.The female animals lay the eggs. Some animals, like birds, then keep their eggs warm; others, like sardines and flies do not keep their eggs warm.

Viviparous animals depends on their mothers when they are a babies. They need to drink their mother's milk.

However, some oviparous animals are independent when they are born. For examples snakes leave their eggs and baby snakes have to move around and find some food. 

Other oviparous animals, like birds, cannot lookafter themselves. The adult animals stays with their babies. They feed and protect them.

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing 

Vertebrates vs Invertebrates

Vertebrates

Vertebrates are animals with a skeleton. The skeleton is made up of bones. The bones are joined together to hold the body up. They protect some parts of the body.
Vertebrate bodies have several parts:

• The head: Vertebrates have a skull to protect their brain.
• The trunk: They have a spinal column, ribs, shoulders and hips in the trunk.
• The limbs: Some vertebrates have legs. Others have wings or fins. Some vertebrates like snakes, have no limbs. Limbs' bones should be long. 
• The tail: This is an extension of the spinal column. Very small vertebrae make up the tail.

Have a look to the following videos:

Invertebrates
Invertebrates animals have no bones (no skeleton).

Some invertebrates have a protective covering:

• Shells are hard and strongs. For instance: a mussel
  
  
   
• Exoskeleton can be thick or thin: For instace: 

• Crabs have thick exoskeletons

• Beetles have thin exoskeletons

Other invertebrates, like jellyfish and worms have no protective covering.

Watch the video:

Insects

Insects are a kind of invertebrates.

All of them have:

• A head : with two eyes, a mouth and two antennae.
• A thorax : In the thorax we can find almost always two or more wings (there are some insects without wings). However all insects will have six legs. If they do not have six legs, they are not insects.
• An abdomen : It is always joined to the thorax. 

Insects are born from eggs. 

Young insects are called larvae. Some larvae are caterpillars. They have no wings or antennae.

All insects breathe air.

Some insects like butterflies are herbivores.

Other insects like dragonflies are carnivores.

Others, like flies are omnivores.

https://www.youtube.com/watch?feature=player_embedded&v=EoLFR3owpfY

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing 

Plants

Plants live in places where they find the things they need:

All plants need:

• Water: They absorb water through their roots. Some plants, like catus can survive with only a little water. Other plants, like ferns, need a lot of water. Some plants, like water lilies, live in water.

Ferns live in wet, shady places.

•  Soil:The roots of the plant fix it to the soil. Plants absorb water and other substances from the soil. They use these substances to make their own food.

 

Wipping willows need a lot of water. They have long roots to absorb as much water as possible.

• Sunlight: They make their food using sunlight. Some plants need a lot of sunlight. Other plantes, like moss, live in very shady places.

Moss needs very little light. 

• The right temperature: Most plants need a warm temperature. Now many plant grow in very cold places

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing 

Animals

ANIMALS

Animals...

They need:

• Water: All animals need water. Most animals live on land although some of them live in water; they are aquatic animals like fishes and dolphins. 

• Food: All animals eat other living things. Depending of what kind of food they eat, we can classify animals in Herbivores (eat plants), carnivores (eat other animals) and omnivores (eat plants and animals).

• The right temperature: Some animals live in very hot places and other animals live in very cold places. Their bodies are adapted to this habitat

Classification of animals
We can classify animals using different criteria:

• If they have skeleton: Vertebrates or Invertebrates
• the way they are born: viviparous or oviparous
• The food they eat: herbivores, carnivores or omnivores.
• The way they move: walk, fly, swim or crawl along the ground

Most part of information and images are taken from the book: Essential Science 4. Science, Geography and History (2006). Santillana Education, S.L / Richmond Publishing