THE UNIVERSE

GALAXIES

•Galaxies are a vast collection of stars, dust and gases.

•They appear in groups called galaxy clusters. (Local Group is our galaxy cluster)

•Our galaxy is the Milky Way.

MILKY WAY

What shape is the Milky Way?Can we see the Milky Way from Earth as it is shown in the image?

Why or why not?

1. WHAT IS THE UNIVERSE LIKE?

Geocentric theory

2nd century B.C.

Proposed by Ptolomy.

The Earth was thecenter of theUniverse.

The Sun, Moon and planets orbited theEarth.

1. WHAT IS THE UNIVERSE LIKE?

Heliocentric theory

In 1542

Proposed by NicolausCopernicus

The Sun was the center of the Universe

¿ASTRONOMY OR ASTROLOGY?

WHEN DID THE UNIVERSE BEGIN?

BIG BANG

17.000 m.y. ago

IS THERE ANY EVIDENCE?

2. HOW BIG IS THE UNIVERSE?

WHAT UNIT OF MEASUREMENT DO

ASTRONOMERS USE?

Astronomical unit (AU) is the distance between the Earth and the Sun= 150 million kilometres.

Express the distance of Mercury, Mars and Pluto from the Sun in kilometres:

Mercury: 0,4 AU =

Mars: 1,5 AU=

Pluto: 39,4 AU=

Light year. It is the distance light travels in a year. Light travels 300,000 km per second.

0,4 x 150.000.000 = 60.000.000 Km

1,5 x 150.000.000 = 225.000.000 Km

39,4 x 150.000.000 = 5.910.000.000 Km

This distance is equivalent to roughly

9,461,000,000,000

4. WHAT MAKES UP THE SOLAR SYSTEM…?

SUN

It’s a medium-sized star.

The Sun consists mainly of two gases: 75% hydrogen (H) and 25% helium (He).

Temperature of the nucleus 15.000.000 ºC. So hot inside that it emits heat and light through nuclear fusion.

It rotates on its axis in an anticlockwise direction (once every 25-30 days)

It was formed when clouds of gases pull together by gravitational forces.

What is the name of the process that takes

place inside the Sun’s nucleus?

What happens during this process?

PLANETS

Planets are spherical bodies which revolve around the Sun.

They move in elliptical orbits.

Mercury, Venus, Earth and Mars are made up mainly of rock. (Rocky planets)

Jupiter, Saturn, Uranus and Neptune are made up mainly of gases. (Gaseous planets)

Rocky planetsor inner planetshave a crust and a mantle made of rock and a metallic core.

Gaseous planetsor outer planetsare made up mainly of gas.

Elliptical orbits

WHICH ARE THE INNER PLANETS?

Mercury

Mercury is the closest planet to the Sun

It is the smallest planet in the Solar System

It has no natural satellites.

It has no atmosphere

There are lots of craters on its surface

Huge differences in night and day

temperatures (From -170ºC to 480ºC)

Venus

Venus is similar in size to Earth.

It has an extremely dense atmosphere which

consists mainly of carbon dioxide (CO2). This

thick atmosphere makes it the hottest planet

of the planetary system, with surface

temperatures over 450°C.

Venus has no natural satellites.

One day in Venus lasts more than one Earth

year.

Earth

Earth is the largest and densest of the inner

planets

It’s the only planet known to have life.

Its liquid hydrosphere is unique among the

inner planets. (Average surface temperature

= 15ºC)

Earth's atmosphere has been altered by the

presence of life to contain 21% free

oxygen. (78% N2)

It has one satellite, the Moon.

Mars

Mars is smaller than Earth and Venus.

It has a thin atmosphere that contains 95%

carbon dioxide, so it’s not breathable.

It’s surface resemble the Earth’s rocky

deserts.

Mars has two tiny natural satellites

(Deimos and Phobos).

WHICH ARE THE OUTER PLANETS?

Jupiter

Jupiter is the largest planet of the Solar System.

It is composed largely of hydrogen (90%) and

helium (10%).

Jupiter has more than 60 known satellites.

The four largest satellites are Ganymede, Callisto,

Io, and Europa.

There are bands of different coloured clouds

around the planet, parallel to the equator.

Saturn

Saturn, famous for its extensive ring

system made of ice, small rocks and dust

particles.

Its composition is very similar to Jupiter’s.

(97% Hydrogen, 3% Helium)

Saturn also has more than 60 known

satellites. The largest one is Titan.

Uranus

Uranus is the lightest of the outer planets.

It’s a frozen planet, with very low surface

temperatures.

One unique feature of Uranus is its axial tilt.

The planet rotates on its side with a tilt over

ninety degrees to the ecliptic.

It also has a ring system

Uranus has 27 known satellites.

Neptune

Neptune is slightly smaller than Uranus.

It has 13 known satellites. The largest one

is Triton.

Elliptical orbits

DW

ARF

PLANETS

They are spherical bodies that orbit the Sun.

They are smaller than planets.

They have not cleared the area in which they orbit.

In the

Asteroid belt

Further than Pluto

DWARF PLANETS Asteroid belt

SM

ALL

SOLAR

SYSTEM

BODIES

These are other celestial bodies that orbit the Sun.

They include asteroids, comets and satellites.

Asteroids

Between the orbits of Mars and Jupiter is located

the Main Asteroid Belt. Asteroids are rocky

bodies that range in size from hundreds of

kilometres across to microscopic.

Comets

Comets are composed largely of volatile ices, dust and fragments of rock. When a comet enters the inner Solar System, its proximity to the Sun causes its icy surface to sublimate and ionise, creating a coma, which is a long tail of gas and dust often visible to the naked eye.

Short-period comets, such as Halley's Comet, are believed to originate in the Kuiper belt (30-1.000 A.U. from the Sun), while long-period comets, such as Hale-Bopp, are believed to originate in the Oort cloud (60.000 A.U. from the Sun)

Satellites or moons

They orbit some planets.

The Earth’s natural satellite is the Moon.

Trans neptunian regions:

Kuipert belt (30-1000 AU) and Oort cloud (60.000 AU)

PLAY THESE GAMES

http://www.educaplay.com/es/recursoseducativos/102

3849/solar_system.htm

http://www.educaplay.com/es/recursoseducativos/102

3852/classify_planets.htm

http://www.educaplay.com/es/recursoseducativos/102

3853/which_planet_.htm

HOW DO THE PLANETS MOVE?

http://esminfo.prenhall.com/science/geoanimations/

animations/01_EarthSun_E2.html