Unit The Earth in the Universe: Origin, Solar System, Earth's Structure

The Earth in the Universe

Unit 1. The Earth in the universe Unit 1. The Earth in the universe

Contents of Unit 1

1Unit 1. The Earth in the universe CONTENTS

1. The origin and evolution of the universe
2. The Solar System
3. The Earth's layers
4. The Earth's changing surface
5. Risks associated with external geological activity

Unit 1. The Earth in the universe 2Unit 1. The Earth in the universe CONTENTS

1. The origin and evolution of the universe
2. The Solar System
3. The Earth's layers
4. The Earth's changing surface
5. Risks associated with external geological activity

Origin and Evolution of the Universe

The Universe and its Components

Unit 1. The Earth in the universe 31. The origin and evolution of the universe The universe, or cosmos, includes everything that exists: all material objects that we can find, the forms of energy that fills the cosmos, the space where these things are found, the time in which the phenomena happen that affect these things and the physical laws that apply there. Edwin Hubble expanded the concept of the universe, proposing that there were more galaxies than the Milky Way.

Galaxies and their Evolution

Unit 1. The Earth in the universe 41. The origin and evolution of the universe The universe is made up of galaxies. A galaxy is a huge group of stars, planetary objects and nebulae gathered around a central core due to the action of gravity. The most common ones are elliptical and spiral. Galaxies evolve over time: galactic cores (quasars) -> small irregular galaxies -> spiral galaxies -> large elliptical galaxies

Types of Galaxies

• Elliptical
• Spiral
• Barred spiral
• Irregular Types of galaxies

The Big Bang Theory

Unit 1. The Earth in the universe 51. The origin and evolution of the universe The Big Bang Theory is currently the most accepted theory to explain the origin of the universe. According to it, the origin of the universe was 13 800 million years ago (mya) with a sudden stage of expansion known as the Big Bang:

• It has expanded and developed the material structures we see today.
• Its temperature and density have decreased as its volume has expanded.
• Its metallicity has been increasing. This theory received a great support with the discovery of the background radiation in 1965. Scientists think this is an echo or shockwave of the Big Bang.

Stages of the Big Bang Theory

Unit 1. The Earth in the universe 61. The origin and evolution of the universe

1. At first, all the energy was concentrated in a small space with high density and temperature (1032K)
2. There was a huge explosion and the universe expanded very rapidly. The first atomic particles - protons, neutrons, electrons- were generated.
3. Within 3 minutes, protons and neutrons fused, generating helium nuclei.
4. Electrons connected to the nuclei, forming the first atoms. The universe became transparent - background radiation began,
5. Matter and energy came together in specific areas. Stars and galaxies formed. The Earth formed around 4 600 mya
6. Currently, the universe continues to expand and everything indicates that it that it will keep doing so in the future.

10.109℃ 6 000 ℃ -250 ℃ -270 ℃ E = m * c2 Big Bang Formation of First galaxies Current universe E=MC 0 1 second 300 000 years 1.109 years 12-15.109 years Age of the universe The Big Bang Theory

The Origin of Matter: Chemical Evolution

Unit 1. The Earth in the universe 7 2 atoms and molecules1. The origin and evolution of the universe THE ORIGIN OF MATTER: CHEMICAL EVOLUTION The nucleosynthesis, or creation of chemical elements in objects in space is due to nuclear fusion processes, that need extreme temperatures and pressure conditions. There are two main processes:

• Primordial nucleogenesis. Few minutes after the Big Bang, H nuclei are formed and join to form He nuclei. The proportion was 75% H and 25% He. Stellar nucleosynthesis. After a few hundred million years, the core of newly formed stars reached the required temperature for nuclear fusion again. Stars became nuclear reactor that generated the rest of the chemical elements. In the final phase of massive stars (>8 solar masses), elements heavier than iron are generated. The starts then explode in the form of supernovae and release moist of the elements into the space.

Stellar Evolution Stages

Unit 1: The Earth in int universe 81. The origin and evolution of the universe STELLAR EVOLUTION All stars go through three stages of stellar evolution:

1. Main pre-sequence (protostars).
2. Main sequence
3. Main post-sequence.

The size of the star also determines other aspects:

• Temperature
• Relative abundance
• Length of life cycle

The Birth and Death of Stars

Nebula Medium sta White dwarf Red giant Planetary nebula Protostar Pulsar neutron star Massive star Supernova Red supergiant Black hole The Birth and Death of Stars - Stellar Evolution Types of stars

Activities on the Universe

Unit 1. The Earth in the universe 9Activities

1. Explain the meaning of the sentence «We are stardust».
2. Why, despite being the most abundant, there are no red dwarfs (M type) among the visible stars at night?

Solar System Overview

Unit 1. The Earth in the universe 10Unit 1. The Earth in the universe CONTENTS

1. The origin and evolution of the universe
2. The Solar System
3. The Earth's layers
4. The Earth's changing surface
5. Risks associated with external geological activity

The Solar System

Components of the Solar System

Unit 1. The Earth in the universe 112. The Solar System The Solar System consists of the Sun (almost 99.9% of the mass of the entire system) and the celestial bodies that orbit it: eight planets and their satellites, dwarf planets, the asteroid belt, the trans-Neptunian objects and comets located in the Kuiper belt and the Oort cloud. Earth Sun Planetary region Kuiper belt Oort cloud Simplified diagram of the Solar System The eight planets in the solar system are classified as inner or rocky and outer or gaseous, according to their composition, density, satellites and rings. Jupiter 3º Uranus Mars 25 Venus 177º ·Pluto (dwarf.planet) 120° Mercury 0.1º Earth 23.5º Saturn 270 Neptune 30°

Origin of the Solar System: Nebular Theory

Unit 1. The Earth in the universe 122. The Solar system THE ORIGIN OF THE SOLAR SYSTEM: NEBULAR THEORY

1. The nebula that started the Solar System came from a supernova.
2. The material from the nebula began to come together as it rotated in the same direction that the Sun and planets do today. It flattened into a disc shape.
3. The temperature rose, due to particles colliding. In the centre, nuclear fusion began and this led to the creation of the Sun.
4. The temperature began to decrease and the vaporised materials condensed; the most refractory materials condensed unflose to the Sun and the most volatile condensed far from it.
5. Gravitational attraction pulled together the condensed fragments which formed larger fragments and then planets.

Characteristics of the Solar System

132. The Solar System CHARACTERISTICS OF THE SOLAR SYSTEM All the planets move around the Sun, on approximately the same elliptical plane. The Sun revolves in the same direction as the planets. Saturn Jupiter The planets move around the Sun in the same direction. Mercury Sun Venus Mars Uranus Earth Asteroid Belt The inner planets are rich in refractory metals and minerals such as silicates. The giant outer planets are composed of gases and volatile2 substances and have only small amounts of iron and silicates. Neptune Pluto (dwarf planet)

Solar System Activities

Unit 1. The Earth in the universe 14Activities

1. How would you explain that all the planets and the Sun rotate in the same direction (counterclockwise, seen from the North pole of the Earth)?
2. Do you think the Sun was at it beginning a solitary star as it is now? Will there be other planetary systems?

Elements of the Solar System

Unit 1. The Earth in the universe 152. The Solar System ELEMENTS OF THE SOLAR SYSTEM The Sun is a yellow G-type star. It's at the halfway point of its stellar evolution, in the middle of main sequence, and still contains enough hydrogen for another 5000 million years. We can classify the eight planets into two large groups:

Types	Planets	Composition	Density	Satellites	Rings
Terrestrial, rocky, inner planets	Mercury, Venus, Earth, Mars	Iron core with silicates rock around it.	High: from 4 g/cm3 (Mars) to 5.5 g/cm3 (Earth)	Hardly any satellites, except the Moon (an exception)	No rings
		Few or no volatile elements (air, water)
Jovian, gaseous, outer planets	Gas giants: Jupiter and Saturn Ice giants: Uranus and Neptune	Very small solid core with gases (H, He) around it or frozen material (water, methane, ammonia, etc.)	Low: from 0.7 g/cm3 (Saturn) to 1.6 g/cm3 (Neptune)	Many satellites (Neptune, 14: Saturn, 82) made up of ice	All have rings; the most obvious are around Saturn.

The Sun-Earth-Moon System

Unit 1. The Earth in the universe 162. The Solar System THE SUN-EARTH-MOON SYSTEM The Moon is the largest satellite in the Solar System, compared to the planet it orbits. Scientists believe it formed when a large planet, called Theia, collided with Earth about 4 500 mya. The impact brough many benefits.

• It stabilised Earth's rotation axis. This prevents Earth from oscillating too much, which would cause big changes in climate and seasons.
• Earth received a lot of iron from Theia's core, which strengthened the magnetic field that protects us from solar wind and another solar radiation.

Unit 1. The Earth in the universe The origin of the Moon

Activities on Earth-Moon System

17Activities

1. Rotation is the movement of the Earth around its own axis. Revolution is its orbital motion around the Sun. How do these movements of Earth and the Moon provide the different cycles we use to measure time: days, weeks, months, seasons and years? Explain the origin of each one.
2. Look at the sequence of an eclipse of the Sun. Draw a diagram to explain the phenomenon, What happens in an eclipse of the Moon? Draw a diagram and label each phase of the Moon: new Moon, waxing crescent, first quarter, full Moon, third quarter and waning crescent.

Phases of the Moon

Earth's Layers and Geological Activity

Unit 1. The Earth in the universe 18Unit 1. The Earth in the universe CONTENTS

1. The origin and evolution of the universe
2. The Solar System
3. The Earth's layers
4. The Earth's changing surface
5. Risks associated with external geological activity

The Earth's Layers

Formation of Earth's Layers

Unit 1. The Earth in the universe 193. The Earth layers Planet Earth, like the rest of the inner planets, was formed by an accretion process. The friction caused by planetesimal impacts and the decay of short-lived radioactive isotopes increased the internal heat, melting the Earth.

• Iron and nickel moved to the center of the Earth, creating the core.
• The degasification created a primitive atmosphere. When temperatures dropped, vapor water formed the hydrosphere.
• The surface of the ocean of magma cooled down and formed the first crust.Unit 1. The Earth in the universe

Silicates Mantle Core Iron 20