UNIT 1: THE UNIVERSE AND THE SOLAR SYSTEM
THE UNIVERSE What are the points of light in this photo?
What’s the difference between
WHAT IS THE UNIVERSE LIKE? The Universe is all the matter , energy and space that exists. The Universe is made up of galaxies which contains stars and planetary systems. Galaxies are a vast of collection of stars, dust and gases, held together by the gravitational attraction. Our galaxy is the Milky Way . Stars are massive spherical bodies of gases. They emit heat and light. Planets are spherical bodies which orbit some stars. They do not emit light. Our planetary system is the Solar System .(8 planets and the Sun) Natural satellites orbit some planets. The Earth’s satellite is the Moon .
Asteroids are rocky objetcs with irregular shape.
Galaxy The Milky Way Asteroid
Galaxies appear in groups called galaxy clusters . The Milky Way belongs to the Local Group galaxy cluster.
Different theories to explain the Universe: Geocentric theory : 2nd Century BC. Ptolomy proposed that the Earth was the centre of the Universe. Heliocentric theory: In 1542 Copernicus proposed that the Sun was at the centre of the Universe.
In 1570 Lippershey invented the telescope, and Galileo proved that the planets revolve around the Sun.
ACTIVITIES Imagine an alien friend from another galaxy wants to write to you. Write your galactic addres. M P L A N E T S I G R L A A S A L U A T S R P T K N E L T T A E Y S E N A H C L W O H B R X E L A T M S U N Y I Y M O O N L G T K E S W C P A E
Make a drawing of the heliocentric and geocentric theories, label their components and the person who proposed it.
HOW BIG IS THE UNIVERSE? The Big Bang theory says that the universe was once in an extremely hot and dense state that expanded rapidly 13.700 millions years ago. The Earth seems huge, but it’s small compared to the Sun. The Sun is 1.300.000 times greater than the Earth. Astronomers use units of measurenment: AU (Astronomical Unit). Approximately 150 million kilometres. Light-year: The distance light travels in one year.
Express the distance of Mercury, Mars and Pluto from the Sun in kilometres.
WHAT MAKES UP THE SOLAR SYSTEM? The Solar System was formed five thousand million years ago from the gas and dust of a nebula . Our Solar System is made up of the Sun , eight planets with their satellites, dwarf planets and small solar system bodies . The Sun consists mainly of two gases: hydrogen and helium . Planets revolve around the Sun in elliptical orbits . Mercury, Venus, Earth and Mars are made up of rock. Jupiter, Saturn, Uranus and Neptune are made up of gases. Dwarf planets are smaller than planets and they orbit the Sun. Pluto .
Small solar system bodies are other celestial bodies which orbit the Sun. They include asteroids, comets and satellites.
HOW DO THE PLANETS MOVE? Celestial bodies like Earth have two types of movement: Rotation : Celestial bodies spin or rotate on an invisible axis. This invisible line is called rotational axis . Revolution: Celestial bodies revolve around other celestial bodies.
An orbit is a curved path which a celestial body follows in its revolution around another celestial body. The orbit of the Earth around the Sun is an ellipse.
ACTIVITIES 1. Do some research at home. Which planet takes the longest to orbit the Sun? Which planet takes the fastest to orbit the Sun? Which planet has the longest day? Which planet has the shortest day?
3. What do you call the imaginary plane of the Earth’s orbit?
WHICH ARE THE INNER PLANETS? The inner planets are the four planets closest to the Sun: Mercury, Venus, the Earth and Mars. They are terrestrial or rocky planets. The crust and mantle are made of rock. The core is metallic. The Earth is the only planet that has life on it.
In 2004, the robots Spirit and Opportunity landed on Mars.
Inner planets Mercury Venus Earth Mars Interesting characteristics The smallest and closest to the Sun Rotates in opposite direction The only planet with life Very thin atmosphere Average surface temperature -180ºC to 430ºC 465ºC -89ºC to 58ºC -82ºC to 0ºC
WHICH ARE THE OUTER PLANETS? Outer planets Jupiter Saturn Uranus Neptune Interesting characteristics Largest planet, most satellites System of rings Rotational axis almost horizontal Greatest distance from the Sun Average surface temperature -150ºC -170ºC -200ºC -210ºC
Jupiter, Saturn, Uranus and Neptune are the four outer planets. They are called gas giants .
Did you know that Pluto used to be a planet? In 2006 the International Union of Astronomers reclassified it as a dwarf planet. Most of the asteroids are between Mars and Jupiter. This area is called asteroid belt.
When comets travel close to the Sun, some of the ice on it evaporates, creating the long, bright tails.
ACTIVITIES Which planet has the most satellites? Which planet is closest to the Sun? Which planet supports life? Which planet is the largest is the Solar System? Which planet spin on its axis in the opposite direction?
Draw a diagram of the Solar System seen from above. Include the rotation and revolution movements of each planet.