Download Earth in the Universe

Unit 3
Earth in the Universe
Origin and Age of Universe
• Celestial object- anything above Earth’s
atmosphere.
• Universe- all the space, matter, and energy
in existence.
• Universe is very vast and more than 10
billion years old.
Origin
• Most scientist believe in the Big Bang
theory.
• All matter and energy started out
concentrated in a small area, after a gigantic
explosion, matter began to organize into
subatomic particles and atoms.
Origin con’t.
More Origin
• Most early atoms where hydrogen and
helium. Within a billion years the atoms
began to form into celestial bodies. As the
bodies got bigger they began to increase
their gravitational forces. This resulted in
the grouping of stars.
• Remember that the universe was expanding
then and is still expanding today.
Evidence for the Bang!
• If the Big Bang did occur, the energy released
would expand along with the matter.
• Radiation from the bang would be mixed with
radiation given off from stars at later times.
• Recently, background radiation has been found to
be coming from all directions in the universe.
• Other evidence lies in the spectrum of the
radiation given off by stars.
Electromagnetic Spectrum
• What is it? Waves of energy transmitted
through space.
• Each element has its own signature
wavelength in the spectrum.
• Scientists compare the wavelengths seen
from space to the wavelengths of known
elements on Earth.
Blue Shift/Red Shift
Blue Shift/Red Shift con’t.
• Doppler effect- the shifting of wavelengths
• How else can you observe the Doppler
effect?
• If an object is moving towards Earth there is
a blue shift (shorter wavelength), if an
object is moving away there is a red shift
(longer wavelength).
More Evidence of the Bang
• The collective light from all the stars in all
the galaxies, except for a few close to Earth,
is shifted to the red end of the spectrum.
• This proves that the universe is indeed
expanding in all directions.
Structure of Universe
• The basic structure of a unit of matter seems
to be a galaxy.
• Galaxy- a collection of stars, gas, and dust
held together by gravity.
• An average galaxy contains over 100 billion
stars! There are more than 100 billion
galaxies!
Galaxy Shapes
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3 types:
Elliptical
Irregular
Spiral
Milky Way Galaxy- our solar system is a
part of this galaxy, and is spiral shaped.
Irregular
Elliptical
Spiral Shapes
Stars
• Make up the majority of known matter in
the universe.
• Star- large ball of gas held together by
gravity and produces a tremendous amount
of energy.
Energy Production
• Result of nuclear fusion- combines the nuclei of
smaller elements to make larger ones. Mass is
converted into energy.
• The sun converts hydrogen into helium with 7% of
the mass converted to energy.
• Nuclear fusion can only occur in extremely high
temperature and pressure situations.
• Energy is released into space as electromagnetic
energy.
Luminosity and Temperature
• Chart is used to classify stars based on their
surface temperature and luminosity.
Luminosity
• Star’s brightness compared to the sun
• Stars change colors depending on their
temperature.
Star Types
• Main sequence- 90 % of stars. Majority of
stars life spent as a main sequence.
• These stars are the average size.
• As they grow their luminosity moves from
red to blue-white.
• Growing results in a higher temperature.
Star Types
• Giant stars- red, orange, and yellow giant
stars are rare, but are commonly seen
because they are so large.
Star Types
• Super giants- 100 to 1000 times the
diameter of the sun.
• Usually explode in a tremendous event
known as a supernova.
• What stars are brightest and the hottest?
Star Types
• White dwarfs- not all are white, but they are
all small (size of Earth).
• Hot on the surface, but low in luminosity.
Star Types
• Black dwarfs- when a white dwarf cools
and no longer emits electromagnetic energy
it is known as a “dead” star/black dwarf.
Star Origin and Evolution
• Start from clouds of gas and dust molecules.
• Clouds are the result of the Big Bang or from stars
that have undergone a supernova.
• Gravity draws these clouds together, forming
larger and larger clouds.
• This process continues until the mass of the cloud
is slightly larger than Jupiter. This gives the “star”
a high enough temperature and pressure to begin
nuclear fusion.
Evolution
• Most of the life of this new born star is
spent in the main sequence. What the star
evolves to next depends on their original
mass.
• Stars with masses similar to our sun expand
to become red giants. When the red giant
uses up its nuclear fuel it collapses into a
white dwarf and then a black dwarf.
Evolution con’t.
• Any star whose mass is 1 ½ times the sun have
much different paths of evolution.
• Exist as a main sequence for a much shorter time,
about 100 million years.
• These stars still turn into super giants.
• They then undergo a supernova and quickly
collapse forming a center that is so dense only
neutrons can exist (neutron star)
• Even larger stars explode into a black hole- allows
no visible light or any other form of energy to
escape.
Solar System
• Any star or group of stars that have non-star
objects orbiting it.
Parts of the Solar System
• Satellites- any object that orbits another object.
• Planets- 9 revolve around sun. 100 planets have
been found revolving around stars other than our
sun.
• Asteroids- solid rocky, or metallic body that
independently orbits the sun. Irregular in shape
and have no atmosphere. Smaller than planets.
More Parts
• Moons- anything that orbits a planet or an asteroid
as those objects orbit the sun.
• Comets- compared to a dirty snowball. Composed
of a mixture of ices of water and methane, and
metallic solids. What happens when a comet gets
too close to the sun?
• Meteoroids- small solid fragments that orbit the
sun. Size of dimes or grains of sand. What is a
meteor?
Evolution of Solar System
• About 5 billion years old. Started as a gas cloud
many times the size of today’s solar system.
Gravitation caused the cloud to condense, most of
the mass was pulled to the center and formed our
sun.
• After Earth and other planets were formed, their
gravity pulled on other smaller objects causing
them to collide with the planets. This is called an
impact event. Where is there evidence for this?
Planet Characteristics
• A planet’s distance from the sun largely
determines its characteristics.
• When the sun was still forming it was much
hotter than today, forcing less dense
elements towards the outer solar system.
• Planets can be divided into two types:
terrestrial and Jovian.
Terrestrial Planets
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Close to the sun and mostly solid.
Small diameters and high densities
Surfaces have impact craters
Have few or no moons and no rings
Name the terrestrial planets.
Jovian Planets
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Far from the sun
Largely gaseous
Relatively large diameters and low densities
No solid surface/could have solid core
Many moons and have rings
Name the Jovian planets.
Motions of the Planets
• Planet rotation- spins on an imaginary axis
- determines a planet’s length of day
- 7 of 9 planets rotate in same direction of
the rotation around the sun.
- periods of rotations can be found in Earth
Science Reference Tables
• Planet revolution- the planet’s motion
around the sun, called an orbit.
Motions of the Planets
• Ellipse- the shape of the orbits of all planets.
• Foci- see page 42 in review book.
• Eccentricity- the amount of difference between an
ellipse and a circle.
Eccentricity of ellipse= distance between foci
--------------------------length of major axis
The closer the number is to zero the closer the orbit
is to resembling a circle.
Varying Distance of Planets from
the Sun
• The Earth is 147 million km away at its
closest point to the sun and 152 million km
away at its furthest point to the sun.
• This does not determine seasons!
click here to see the solar system drawn to
scale
Inertia, Gravitation, Orbital
Velocity/Speed, and Planet
Orbits
• Inertia- an object at rest will remain at rest, and an
object in motion will maintain the speed and
direction of that motion unless an opposing force
acts upon it.
• Gravitation- the attractive force between any two
objects.
- The greater the mass of one or both of the objects,
the greater the attraction.
- The closer the two objects together the greater the
attraction.
- What causes a planet to maintain its orbit?
Inertia, Gravitation,
Orbital Velocity/Speed, and
Planet Orbits
• Keeping in mind that each planet’s orbit has some
degree of eccentricity, is the orbital velocity the
same all the time?
• When is it fastest?
• When is it slowest?
• Revolution- the time it takes a planet to go all the
way around the sun. Explain how a planet’s
distance from the sun determines the speed of a
planets revolution.