1. 1 BUnit 1: The Earth, the living planet

2. The universe, the solar system and the EarthThe universe has begun 13.700 milion of yearsago.includes:celestial bodies (stars, planets, satellites...)intergalactic matter (dust and gas)intergalactic space 3. The celestial bodies form GalaxiesEach galaxycontains milionsof milions of starsand manyplanetarysystems 4. The planetary systemsconsists ofA starthe celestial bodies that goaround it (planets, satellites,asteroids and comets). 5. The Earth, the living planet- was formed 4.600 milions ofyears ago, like the Sun and allthe solar system.- is the only planet with life 6. Why the Earth is the only planet with life?1. Temperature is moderate.2. The atmosphere contains essentialgases for human life, as oxygen. Besides,the atmosphere protects us from unhealthysolar radiations and it helps us keeping itstemperature.3. The Earth has plenty of liquid water.This water is a large part of the Earth'ssurface, forming oceans and seas, for thisreason, we see the Earth from space blue. 7. Shape and dimensions of the Earth-The Earth' shape is almost spherical which iswhy it is represented by a globe.-The Earth has 510 milions of km2, a thousandtimes Spain' surface.-The Earth is a small celestial body in the wholeuniverse. 8. The Earth in motionThe universe and its asteroids are constantly moving.The Earth is constantly movingRotationOrbiting 9. RotationRotation is the turning of the Eartharound its imaginary axis; at eitherend of the axis are the poles. Afull rotation takes 24 hours (a day)The main consequences of the Earths movement arethe change from day to night and vice versa. 10. Whats happen if the Earth doesnt rotate?I f t h e E a r t h d o e s n o t r o t a t e , h a l f o f t h e p l a n e t w o u l d a l w a y sb e l i g h t a n d t h e t e m p e r a t u r e w o u l d b e e x t r e m e l y h o t w h i l et h e o t h e r h a l f w o u l d b e i n d a r k n e s s a n d w o u l d b e e x t r e m l yc o l d . 11. OrbitingThe orbit is the movement of the Earth around the Sun.It takes 365 days, 6hours and 9 minutes. 12. Consequences of the Earths' orbit The season of the year: Due to orbiting and the inclination of the Earth'saxis, each of the two hemispheres has a different exposure (exposicin) tothe Sun's rays.- In summer the rays fall directly on one hemisphere, while the otherreceives them with a strong inclination, making winter.- In spring and autumn the rays fall on both hemispheres with thesame inclination. When it is spring in one hemisphere it is autumn in theother. Different duration of night and days.The different climate zones: depending on the latitude, the Sun's raysfall with a different inclination. We can distinguish:- One warm zone-Two temperate zones.Cold zone- Two cold zones.Warm zoneTemperate zoneCold zone