OUR PLANET, THE EARTH

The Earth’s Features

• It is a rocky planet.• Its atmosphere contains oxygen.• Its average temperature is 15 ºC.• Water: solid, liquid, gas: water cycle.• A natural satellite: The Moon produces

tides.• Life exists.

THE EARTH IN THE UNIVERSE

Look at these two images, and find the differences.

Which one do you think is correct?

https://www.youtube.com/embed/Oc6yPFoqLF4?wmode=transparent

Geocentric Model

• The Earth is at the centre of the Universe.

• Proposed by ancient civilizations.

• Remained until 16th century.

Heliocentric Model

• The Sun is at the centre of the Universe.

• Proposed by Copernicous, Kepler and Galileo Galilei (*).

RotationRevolution

MOVEMENTS OF THE EARTH

Rotation Movement

• Is the spinning of the Earth on its axis.

• The time for one rotation is 24 hours.

• The speed of rotation is about 1.700 Km/h at the Equator.

Rotation consequences

Day and Night

http://recursostic.educacion.es/secundaria/edad/1esobiologia/1quincena4/imagenes1/movimtos.swf

Revolution Movement

• It is our planet’s movement around the Sun.• It describes an eliptical orbit.• It takes 365 days to complete a revolution.

Revolution consequences

June 21stDecember21st

September 22nd

March 20th

The Seasons

http://conteni2.educarex.es/mats/14393/contenido/interfaz.swfhttp://www.edistribucion.es/anayaeducacion/8420534/U02/U02_01_EPI_02/video_estaciones.html

THE EARTH’S SPHERES

GEOSPHERE

• Is the solid (rocky) part of Earth. • We can distinguish three parts in it:

– Crust.– Mantle.– Core.

HIDROSPHERE

• Is all the water on, under and above the Earth:– Solid (ice).– Gas (water vapour).– Liquid: salty / fresh.

ATMOSPHERE

• The layer of air which sorrounds the Earth.– It contains the oxygen we breath.– It blocks dangerous solar radiations: UV.– It keeps an adequated temperature for life.

BIOSPHERE

• All the living things which inhabit the Earth.

THE MOON

• It is our only natural satellite.• It was formed at the same time than the Earth.• It rotates (its day takes 29 terrestrial days).• It orbits the Earth at 3.680 Km/h.• It takes about 28 days to orbit the Earth.• It has no atmosphere, so it suffers lots of meteorites

impacts, which can form craters.

Las Fases de la Luna

http://rincones.educarex.es/byg/index.php/1-eso-la-tierra-en-universo/animaciones?showall=1&limitstart=

ECLIPSES

• Sometimes during their orbits, the Moon and the Earth form a line with the Sun. When this happens, an eclipse occurs.

LUNAR ECLIPSE

It happens when the Earth moves between the Sun and the moon, blocking part of the Sun's light from reaching the moon. So, we will see the Earth's shadow on the moon.

SOLAR ECLIPSE

It happens when the Moon moves between the Earth and the Sun. So, part of the Sun's light is blocked.When the moon and Sun are in a perfect line, it is called a Total Eclipse.