8. The Universe and the EarthBIOLOGY AND GEOLOGY. ANAYA 1ST ESO.

Ana Rupérez Romero

Ancient civilizations

Mythology

Earth motionless and flat

Sky was a dome with the stars.

Greeks

Earth is spherical body

Earth floats in space like other celestial bodies

Geocentric

model

Ptolemy in 2nd century AD

Earth round and at the center of the universe

Other celestial bodies revolved around

Sphere with fixed stars

Planets known: Earth, Venus , Mars, Jupiter and Saturn

Heliocentric

model

Aristarchus and Copernicus

The Sun is at the center of the universe

The other planets revolve (orbit) around the Sun.

The Moon orbits the Earth.

The Stars are on a fixed Sphere.

Current idea of universe

The sun is not at thecenter of the Universe, only at the center of

the Solar System.

The orbits of the planets are not

circles, but elipses.

The stars are not in a fixed sphere but in a

Galaxy.

The universe is allMATER, ENERGY AND

TIME

The Universe isexpanding: galaxies

are separating

Occupies anenormous space

The BIG BANG was the first explosion.

Some definitions:

Universe: All matter energy and time that exist. Itoccupies an enormous space (100 000 million light years)

Galaxies: collections or stars and nébulas.

Nebulas: clouds of dust and gas. They are the places where stars are born and they can also come fromexplosions of stars.

Stars: are enormous spheres of matter that emit energy(with nuclear reactions transforming hydrogen intohellium)

Solar systems: formed ussually by one star, planets, moons, asteroids, comets, dwarf planets….

Big Bang: is the name for the first explosión that createdthe universo. Galaxies are moving away from eachother. The universe is getting bigger and expanding. Ithappened around 14 000 million years ago.

Relative sizes

Video

Distances in the universe

1 Astronomic Unit: AU is 150 000 000 km. 150 million km

Speed of light: 300 000 km/s

1 year has: 60*60*24*365= 31 104 000 seconds

31 104 000s x 300 000 km/s is the distance that light covers in 1 year

Light year: 9 500 000 000 000 km, 9,5 billion km

Closest star to the Earth: Alpha Centauri (4,3 light years>>

41,32billion km)

Our solar system

Located in the Milky Way (100-400 billion stars)

The Milky Way belongs to the Local Group (20 galaxies)

The Local Group is in the Virgo Supercluster.

Celestial bodies in the Solar System: The Sun

Planets (8)

Satellites

Dwarf planets

Asteroids

Comets

The Sun video

The sun

Medium sized star.

Located in one of the spiral arms of the Milky Way

Movements: rotation around its axis and with the

Galaxy.

Sends energy in forms of heat and light. Also sends

solar wind (with particles) video of solar wind.

Sun age: 5000 million years

Sun will die in 4500 million years

Types of stars

Planets

Spherical celestial bodies that orbit a star.

Reflect sunlight (they can´t produce their own light)

They travel in elliptical orbits around the sun

All the orbits are located in the same plane: the

ecliptic plane

ROCKY or INNER: Mercury, Venus, Earth and Mars

Small, made of rock, weak atmosphere.

GAS or OUTER: Jupiter, Saturn, Uranus, Neptune.

Big, small solid nucleus, large and thick atmosphere,

many satellites and rings.

Planets of the solar system

Rocky or inner planets:

• Rocky surface

• Dense materials

• Atmospheres tenuous (tenues)

• Smaller in size

• Mercury, Venus, Earth and Mars

Gaseous or outer planets

• Further

• Low density substances in gaseous state

• Atmospheres very thick covering a tiny solid nuclei

• Size very large and a slower speed

Satellites

Spherical (or not) bodies that orbit a planet.

Rocky planets have none, one or two satellites.

Venus and Mercury: none

Earth: one (the Moon). Mars:two (Phobos and Deimos)

Gas planets have many satellites.

Jupiter: more tan 60. Galilean Satellites are 4: Callisto, Europa, Io and Ganimedes.

More definitions

Dwarf planets: spherical bodies (Pluto and Ceres) that

orbit a star but their orbits are not free of other objects.

Asteroids: Irregular rocky bodies that orbit around the

Sun (in the Asteroid Belt or Kuiper belt). The trajectory

can change.

Comets: small bodies made up of rock and ice. Come

from the Kuiper belt. Very elliptical orbits. The

fragments can become meteorites.

Meteor shower or shootting stars

Our solar

system

Watch the following videos about our solar

system:

The origin of the solar system:

http://www.watchknowlearn.org/Video.asp

x?VideoID=55507&CategoryID=2813

Solar System:

Formation of Solar System: video 1(Stephen Hawkins), video 2

Formation of the solar

system

1. The nebula begins to condense and revolve.

2. The rotation caused the nebula to take the shape of a flat disc: the protoplanery disc (most matter at thecenter)

3. The matter at the center concentrates more and more>> pressure and temperatura make nuclear reactions>>> the Sun is formed.

4. The rest of the materials were send outside the center and revolved around the Sun at different distances>> Planetesimals were formed (the heaviest one close to theSun will form rocky planets and the lighter ones will formthe gas planets.)

5. Planetesimals attract the materials in their orbits and formed larger and larger planetesimals that eventuallybecame planets.

Crab nebula5th July 1054. The story of a supernova.

Crab nebula is the first supernova that has been witnessed in the

whole world (China, America, native Anasazi..). During the explosion it

could be seen even at daytime and later stayed visible for 22 months

Crab nebula is 6300 light-years away from us. Therefore, the real

explosion was in 5246 before Christ although its light didn’t arrive to us

until later.

Explosion

Supernova

5246 BC

Year 0

Observed

1054 AC

Some constellations of the Milky Way

Constellation: group of stars forming a recognizable pattern

(drawing) that is named after the form of the figure (mythological

figure). The sky is divided into 88 regions called constellations.

Stars in a constellation are not closed together, they look

together because apparently have the same brightness.

Orion

Finding the North: Pollaris

Ursus Major or Big Dipper is one of the constellations that can be

seen the whole year because they are close to Polaris. They are

named circumpolar.

Other circumpolar constellations are:

Casiopea, Perseus, Draco or Cepheus

Stars in a costellation are at different distances from us.

Meanings of the names of the planets and

curiosities more curiosities planets like the moon

PLANET CURIOSITY

Mercury God Messenger of Roman gods. Faster. Smaller planet, no atmosphere, no moons, 88 days

revolution, 59 days rotation. 430ºC at day, -170 degrees at night

Venus Godess of love and beauty. Clouds of carbón dioxide. White and dense atmosphere.

Surface very hot. Lava. It rains sulphuric acid. Morning star. Evening star. Second brightest

object after the moon. Similar size to Earth. High greenhouse effect. It rotates in the other

direction. Impact of something turned it upside down

Earth Life. Water 3 states (solid, liquid, gas) . Temperature of 15 degrees of average. Axis tilted 23,5

degrees>> seasons

Mars God of war. Red planet. Smaller than Earth. No internal activity. Olympus (22km). Rests of

wáter. Ice caps. Pathfinder explore>> bacterias. Future colony, Two moons: Phobos, Deimos

Jupiter King of Gods. Bigger. Storm 200 years. Faster rotation (10hours) Magnetosphere. Aurora. 4

main moons: Europa, Callisto, io, Ganymedes. Discovered by Galileo with telescope (1610)

Atmosphere with stripes. Hydrogen and hellium. Weight higher than all the other planets

together

Saturn Second big planet. Titan. Rings of ice and gas.1km thick. More tan 60 satellites. Titan has

atmosphere. Very light, it would float. Is the farthest planet you can see without telescope.

Uranus God of air. Spins like from a side, like a Rolling ball. Blue. Several moons. Rings very thin

Neptune God of oceans and wáter. Blue. Farthest planet. Similar to Uranus in size

Our planet: the Earth

The movements of the Earth

The Earth moves in

two different ways:

• Rotation.

• Revolution.

• https://www.youtube.com/wat

ch?v=lkWyM-M8o0c

Rotation

The Earth rotates (spins) on its

own axis.

Its axis is an imaginary line

between the North Pole and

the South Pole.

The axis is tilted 23.5º with

respect to the perpendicular

line to the ecliptic plane

The consequences of rotation

The rotation of the Earth every 24 hours causes day and night.

• It is day time on the side of Earth where the sun shines.

• On the other side of Earth is night.

https://www.youtube.com/watch?v=R3jr0DaV8N8

The consequences of rotation

Rotation sense is

counterclockwise.

Sunrise or dawn: when the

sun first appears in the

morning>> EAST

Sunset or twilight: the sun

disappears in the

evening>> WEST

Revolution

The Earth revolves around the Sun.

The Earth takes 365 days, 6 hours and 9 minutes

to complete the revolution = a sideral year.

The consequences of revolution:

the seasonsTwo factors cause the seasons:

• The revolution of the Earth around the Sun

• The tilt of the Earth’s axis of rotation respects to the Plane of the Ecliptic.

• Video on seasons solstices and equinoxes

• https://www.youtube.com/watch?v=tX3Y5bzNDiU

Solstices equinoxes and seasons

Solstices and equinoxesSolstices: Maximum

difference between day

and night.

Equinoxes: Day

and night have

the same length.

Sun hits perpendicular to

the equator.

March, 20/21

September 22,23

Sun is at the highest or lower

point.

December, 21/22 is the

shortest day

June, 21/22 is the largest day

The seasons in the Northern

Hemisphere

During the summer in the northern hemisphere, the

temperature is higher because there are more hours of

daylight and because the Sun rays hit the Earth surface at an

angle of 90º. During the winter, Sun rays are more tilted and

that´s why is colder.

In the South Hemisphere is the opposite.

During the seasons, temperature changes

depending on angle at which the Sun’s rays

hit the Earth.

Our satellite: the Moon

Movements of the moon: Rotation of the moon: It takes 27.3 Earth days to rotate on its axis.

Revolution of the moon: Moon orbits the Earth every 27.3 Earth days.

Libration (see the gif on this page. The libration is that Little movement)

Same side of Moon always facing the Earth. (there is a far side of themoon we never see)

Video on Moon phases

Origin and formation of the moon

Phases of

the moonMoon calendar

Newmoon

First quarter

(crescent moon)

Full moon

Last quarter

or Third quarter (decreasing

moon)

The 4 phases repeat every 29

days (7 days each main

phase)

Eclipses

Eclipses:

Solar eclipse; the Moon is alligned with the Earth and the Sun.

Lunar eclipse: the Earth is between the Sun and the Moon.

https://www.youtube.com/watch?v=kgbK2FZFFdw&t=83s

Tides

Tides:

Periodical rise and fall of the sea level.

They are caused by the gravitational force of theMoon and, to a lesser extent, the Sun on the

water masses of the Earth.

https://www.youtube.com/watch?v=9rkfk9TJ52I

Images of high/low tides

High tides: the sea level rises

Low tides: when the sea level moves down.

Tide changes every 6 hours.

There are 2 high tides and 2 low tides every 24 hours

Spring tides (mareas vivas) and

neap tides (mareas muertas)

Tides

Neap tides (mareas muertas)>> First and last quarters. Little difference betweenhigh and low tidessea levels.

Spring tides (mareas vivas) >> Full moonand new moon Big difference betweenhigh and low tidessea levels.