ASTRONOMYNebular Theory, Stellar Evolution and the Big Bang Theory

23.1- The Solar System The Planets: An Overview

The 8 planets in our solar system can be separated into two different categories1. Terrestrial planets2. Jovian planets

23.1- The Solar System1. Terrestrial planets (inner planets)

Includes Mercury, Venus, Earth, Mars Relatively small and rocky What does terrestrial translate to?

“Earth-like”2. Jovian planets (outer planets)

Includes Jupiter, Saturn, Uranus, Neptune Huge gas giants What does jovian translate to?

“Jupiter-like”

23.1- The Solar System

23.1- The Solar System The Planets: An overview

Size is the most obvious difference between the terrestrial and Jovian planets The Jovian planets are giants compared to the terrestrial

planets Density, what the planet is made of, and the rate of

rotation are other ways in which the two groups of planets differ Jovian planets are less dense while terrestrial planets are

more dense Jovian planets are made of gas Jovian planets rotate around the sun much slower than the

terrestrial planets

23.1- The Solar System

23.1- The Solar System The Planets: An Overview

The Interiors of the Planets All planets (and Pluto) are made up of

gases, rocks, and ice The Atmospheres of the Planets

Jovian planets have thick atmospheres of hydrogen, helium, methane and ammonia

Due to the large amount of gravity on these planets

Terrestrial planets have thin atmospheres

Due to the small amount of gravity on these planets

23.1- The Solar System Formation of the

Solar System Nebular Theory

A nebula is a cloud of gas and dust in space

According to the nebular theory, the sun and planets formed from a rotating disk of dust and gases.

As the disk rotated faster the sun formed in the middle

23.1- The Solar System Formation of the Solar

System Nebular Theory

Planetesimals Planets grew as solid bits of

matter began to collide and clump together through a process known as accretion.

The colliding matter formed small irregularly shaped bodies called planetesimals

As the collisions continued these planetesimals grew into planets

https://www.youtube.com/watch?v=PL3YNQK960Y

23.2- The Terrestrial Planets Mercury: The Innermost Planet

The innermost and smallest planet in our solar system; just slightly larger than Earth’s moon

Surface Features Has craters, similar to our moon.

Surface Temperatures Has the greatest temperature extremes of any

of the planets It can get as cold as -173°C at night and as hot as

427°C during the day

23.2- The Terrestrial PlanetsMercury’s Surface

23.2- The Terrestrial Planets Venus: The Veiled Planet

Called “Earth’s twin” Venus is similar to Earth in size, density, mass,

and location in the solar system. Surface Features

Covered in thick clouds that prevent light from hitting the planet

About 80% of Venus’s surface is covered in volcanoes

Surface Temperatures Atmosphere is 97% carbon dioxide, making it

VERY HOT!

23.2- The Terrestrial PlanetsVenus’s Surface

23.2- The Terrestrial Planets Mars: The Red Planet

The Martian Atmosphere Contains carbon dioxide with a small amount of

water vapor Extensive dust storms on Mars cause it to look

different colors at times through a telescope from Earth

Surface Features Consists of canyons, inactive volcanoes, and

craters These features are billions of years old

23.2- The Terrestrial Planets

23.2- The Terrestrial Planets Mars: The Red Planet

Water on Mars Some areas of Mars exhibit drainage patterns

similar to those created by streams on Earth Images from the Mars Global Surveyor indicate

that groundwater has recently migrated to the surface

http://www.cnn.com/2014/02/10/tech/innovation/mars-water-flows/

23.3- The Jovian Planets (and Pluto)

Jupiter: Giant Among Planets Jupiter has a mass that is 2.5 times greater

than the mass of all the other planets and moons in our solar system combined.

Structure of Jupiter Contains several gases such as hydrogen,

helium, methane, ammonia, and water Incredibly windy and cloudy

The “Great Red Spot” is a large storm, similar to that of a hurricane

23.3- The Outer Planets (and Pluto)

23.3- The Outer Planets (and Pluto) Jupiter: Giant Among Planets

Jupiter’s Moons Jupiter has 63 moons, which makes it resemble

a mini solar system Jupiter’s Rings

One of the most unexpected discoveries made by Voyager 1

Thought to be formed of fragments from the collision of meteorites hitting two of Jupiter’s moons.

23.3- The Outer Planets (and Pluto) Saturn: The Elegant Planet

The most prominent feature of Saturn is its rings

23.3- The Outer Planets (and Pluto) Saturn: The Elegant Planet

Features of Saturn Saturn’s atmosphere is very active, with winds roaring

up to 1500 km/hr Large storms similar to Jupiter’s “Great Red Spot”

Saturn’s Rings Was once that that this was the only planet to have

rings The inner rings are more densely packed with particles

while the outer rings are less densely packed with particles

Saturn’s Moons Contains 31 moons The largest moon is Titan, which is larger than Mercury

23.3- The Outer Planets (and Pluto) Uranus: The Sideways Planet

Uranus is unique in that it rotates on it’s side

23.3- The Outer Planets (and Pluto) Neptune: The Windy Planet

Winds exceeding 1000 km/hr make it one of the windiest places in the solar system

23.3- The Outer Planets (and Pluto) Pluto: Dwarf Planet

Until 2006 Pluto was considered to be a planet

Pluto is not considered to be a planet because its gravity is too weak to attract all nearby debris

As a result, the term Dwarf Planet was created. Dwarf Planet: a round object that orbits the

sun but doesn’t have a gravitational field strong enough to pull in all nearby debris

23.3- The Outer Planets (and Pluto) Pluto: Dwarf Planet

23.4- Minor Members of the Solar System Asteroids

Definition: small rock bodies that orbit the sun

Most asteroids lie in the asteroid belt between Mars and Jupiter.

Asteroids also have irregular orbits

23.4- Minor Members of the Solar System

Comets Definition: Pieces of rocky and metallic

materials held together by frozen water and gases

Comets also orbit the sun

23.4- Minor Members of the Solar System

Meteoroids Meteoroid: a small, solid particle that

travels through space Meteor: the phenomenon observed when a

meteroid enters Earth’s atmosphere and burns up, popularly called a shooting star

Meteorite: any portion of a meteoroid that reaches Earth’s surface

23.4- Minor Members of the Solar System

Meteoroids Meteoroids originate in one of the following

ways1. Debris that was not swept up by the gravity of

other planets during the formation of the solar system

2. Material from the asteroid belt3. Solid remains of comets that once traveled

near Earth’s orbit

24.1-The Study of Light How do scientists know all this

information about the planets? And how do they know so much about objects that are further away, such as stars? The majority of the information we know

about the universe is obtained from the study of light emitted from stars and other bodies in space.

24.1-The Study of Light Electromagnetic Radiation

Stars give off electromagnetic radiation (waves)

These electromagnetic waves have different wavelengths

Electromagnetic Spectrum

24.1- The Study of Light Electromagnetic Spectrum

The human eye can only see a certain range of wavelengths, in what is called the continuous spectrum

The continuous spectrum is caused by things like the sun or light bulbs

24.1- The Study of Light Electromagnetic Radiation

Emission spectrum Also known as “bright line spectra” These lines are made by glowing elements in a star,

and can be seen with an instrument called a spectroscope

Below is the emission spectra of hydrogen produced by a star

24.1- The Study of Light Electromagnetic Radiation

Absorption Spectrum When a visible spectrum of a star passes

through the cooler outer atmosphere of the star

24.1- The Study of Light Electromagnetic Radiation

Absorption Spectrum The gas in a star absorbs certain wavelengths

of light, resulting in the appearance of dark lines

Most common spectra of stars Also known as “dark line spectra” Each spectrum is like a fingerprint of a star,

telling us what element the star is made up of

24.1- The Study of Light The Doppler Effect

Moving sound sources produce perceived changes in pitch compared to the location of the observer

https://www.youtube.com/watch?v=h4OnBYrbCjY In astronomy, the doppler effect is used to

determine whether a star or other body in space is moving away from or toward Earth

24.1- The Study of Light The Doppler Effect

Red Shift Objects moving away from the

observer exhibit a longer wavelength, or a shift towards the red end of the electromagnetic spectrum

Using the doppler effect, scientists have discovered that all stars and galaxies in the universe are red shifted. What does this mean?

All stars and galaxies in the universe are moving away from each other and the universe is expanding

24.2- Tools for Studying Space Telescopes

Instrument that aids in the observation of distant objects, such as stars and planets, that give off electromagnetic radiation

Types of Telescopes1. Refracting Telescopes2. Reflecting Telescopes3. Radio Telescopes4. Space Telescopes

24.3- Tools for Studying Space Types of Telescopes

1. Refracting Telescopes Telescope that uses a lens to bend, or refract,

light. The objective lens bends all of the light rays

onto one spot, the focus, or central point, so that the eye can see the object clearly

24.3- Tools for Studying Space Types of Telescopes

2. Reflecting Telescopes A telescope that reflects light off of a mirror before it

focuses the image Benefits of the reflecting telescope

Lighter than the refracting telescope Produces a clearer image

24.3- Tools for Studying Space Properties of Reflecting and Refracting Telescopes

Both reflecting and refracting telescopes have 3 properties that aid astronomers in their work1. Light-gathering power (can see dim objects)2. Resolving power (can see images clearly)3. Magnifying power (can see small objects)

24.3- Tools for Studying Space Types of Telescopes

3. Radio Telescopes Detect radio waves emitted by far away stars in space A satellite TV setup is really just a simple radio

telescope

24.3- Tools for Studying Space Advantages of Radio Telescopes

Less affected by the weather Cheaper to build Can be used during the day Can “see” through interstellar dust and clouds

24.3- Tools for Studying Space Types of Telescopes

4. Space Telescopes Orbit above Earth’s atmosphere Advantages:

Above clouds and the Earth’s atmosphere Can be used during the day

Disadvantage: Expensive; if it breaks there is no way to fix it

24.3- Tools for Studying Space Types of Telescopes

4. Space Telescopes Hubble Space Telescope

Launched in 1990 by the space shuttle “Discovery” Photos are much higher in quality than Earth based

reflecting or refracting telescopes

25.1- Properties of Stars Characteristics of Stars

Star Color and Temperature Color is a clue to a star’s temperature

Red is cool Blue is hot

25.1-Properties of Stars Characteristics of

Stars Binary Stars and

Stellar Mass Binary stars are two

stars that revolve, or rotate, around each other

They rotate around each other at their center of mass.

Because of this, binary stars are used to find the mass of stars

25.1-Properties of Stars Measuring Distances to Stars

Parallax Slight shift in the apparent position of a star in the sky The closer the star, the more it appears to move in the night sky The further away the star, the less it appears to move in the

night sky

25.1-Properties of Stars Measuring Distances to Stars

Distances to stars are so large that units such as kilometers are too hard to use.

Scientists instead measure the distance to a star in light years Light Year

The distance light travels in 1 year

25.1-Properties of Stars Stellar Brightness

The measure of a star’s brightness is its magnitude Apparent Magnitude

Brightness of a star when viewed from Earth 3 factors control the apparent brightness of a star

from Earth1. How big it is2. How hot it is3. How far away it is

Absolute Magnitude How bright the star actually is from a distance of

32.6 light years away

25.1-Properties of Stars Hertzsprung-Russell Diagram (HR

Diagram) Shows the relationship between the

absolute magnitude and temperature of a star

HR Diagram

25.1-Properties of Stars HR Diagram stars

Main Sequence star Star that falls into

the main sequence category on the diagram

90% of stars fall along this part of the diagram

Hottest stars are the brightest (blue)

Coolest stars are the dimmest (red)

25.1-Properties of Stars HR Diagram stars

Red Giant Large, cool bright

star; it is in the upper right corner of the HR Diagram

Supergiant Bigger and

brighter than a red giant

White Dwarf Extremely small

star

25.2-Stellar Evolution Star Birth

Stars are born in interstellar clouds, or nebulae

25.2-Stellar Evolution Star Birth

Protostar stage A collapsing cloud of gas and dust in the

process of becoming a star When the center of a protostar has reached

about 10 million °C, nuclear fusion of hydrogen begins and a star is born

As hydrogen atoms fuse together they create helium atoms, which stay in the center of the star.

As a result, the remaining hydrogen fusion moves outward and away from the center of the star

25.2-Stellar Evolution Main Sequence Stage

Different stars age at different rates Massive stars exist for only a few million years Small stars exist for perhaps hundreds of billions of years A star spends 90% of its life on the main sequence stage of

the HR Diagram

Red Giant Stage Remember, hydrogen fusing has continued to move out

and away from the core The red giant forms when hydrogen fusion ONLY occurs

on the outermost part of the star (NOT the core) This causes the star to cool (become red) and expand

(become a giant)

25.2-Stellar Evolution

25.2-Stellar Evolution Burnout and Death

All stars eventually run out of fuel and collapse

Death of Low-Mass Stars Die as a white dwarf without ever turning into a

red giant Death of Medium-Mass Stars

As the red giant collapses into a white dwarf a cloud of gas called planetary nebula is formed

25.2-Stellar Evolution Burnout and Death

Death of Massive Stars A supernova is an

exploding massive star Will produce either a

neutron star OR a black hole

Crab Nebula; remnants of a supernova that took place in 1054

Stellar Evolution

25.2-Stellar Evolution Stellar Remnants

White dwarfs Core of a burned out star When it cools down it will be called a black

dwarf Neutron Stars

Star of extremely high density composed entirely of neutrons from atoms

Produced from a supernova

25.2-Stellar Evolution Stellar Remnants

Black Hole Dense objects with gravity so strong that not

even light can escape their surface

25.3- The Universe Types of Galaxies

A galaxy is a large group of stars, dust, and gases held together by gravity

There are 3 types of galaxies1. Spiral Galaxies2. Elliptical Galaxies3. Irregular Galaxies

25.3- The Universe Types of Galaxies

1. Spiral galaxies Disk shaped galaxies

2 types1. Spiral galaxy2. Barred spiral

galaxy Contain old and young

stars Younger stars are in

the arms 30% of galaxies are spiral galaxies

25.3- The Universe Types of Galaxies

2. Elliptical galaxies Range in shape from round to oval Contain only old stars About 60% of galaxies are elliptical galaxies

25.3- The Universe Types of Galaxies

3. Irregular galaxies Have irregular shapes Contain only new stars Only 10% of galaxies are irregular galaxies

25.3- The Universe The Milky Way

The name given to our galaxy

Spiral galaxy

25.3- The Universe The Expanding Universe

Red Shifts Galaxies in the universe are red shifted,

meaning they are moving away from Earth. A scientist by the name of Edwin Hubble set out

to explain why this occurred. He realized that brighter stars must be closer to

Earth and dim stars must be far away from Earth He attempted to explain the red shift phenomenon

by determining if a relationship existed between the distance to a galaxy and its red shift

25.3- The Universe The Expanding Universe

Hubble’s Law Hubble discovered that galaxies further away

from Earth have a bigger red shift than those closer to Earth

This means that objects move even faster as the get further away from Earth

This indicated that the universe is expanding

25.3- The Universe The Big Bang Theory

States that at one time, the entire universe was confined to a dense, hot, supermassive ball.

13.7 billion years ago, a violent explosion occurred, hurling this material in all directions

A few seconds after this big bang the universe cooled enough to allow protons, neutrons, and electrons to form These are the building blocks for all matter

A few thousand years after the big bang atoms formed The majority of these atoms were hydrogen and helium

atoms Giant clouds of these hydrogen and helium atoms

gathered together to form stars and galaxies

25.3- The Universe Supporting Evidence of the Big Bang

Theory1. In the 1960’s scientists discovered a type

of energy called background radiation. This was detected as faint radio signals coming from every direction in space thought to be produced during the big bang

Bill Nye clip 26:452. There is an extremely large amount of

hydrogen and helium in our atmosphere3. The galaxies in our universe are moving

further away from each other