THE UNIVERSE · BIG BANG THEORY •The most widely accepted theory of the universe today is the BIG...
Transcript of THE UNIVERSE · BIG BANG THEORY •The most widely accepted theory of the universe today is the BIG...
THE UNIVERSE
CHAPTER 20
THE UNIVERSE
• UNIVERSE – everything physical in __________ and ____________
– Includes all space, matter, and energy that has existed, now exists, and will exist in the future.
– How did our universe form, how did evolve to what it is today, and what will it be doing in the future???
BIG BANG THEORY
• The most widely accepted theory of the universe today is the BIG BANG THEORY!
BIG BANG THEORY: • Occurred _________ billion years ago • All energy and matter was compressed into a
single point that was infinitely dense and small • That point began to
________________extremely rapidly in a “big bang”
BIG BANG THEORY
• IMMEDIATELY AFTER THE “BIG BANG” – The universe existed of pure energy
– The universe was extremely _________ and ____________________quickly
– The universe began to ____________ allowing sub-atomic particles to form
– _________________ pulled atoms together into gas clouds that eventually formed stars, which eventually formed galaxies
– The universe is still __________________ today
EVIDENCE FOR BIG BANG THEORY • ________________________
• Edwin Hubble – 1929 – Stated the universe is
expanding
– Studied spectra “color” from galaxies
– He saw galaxies appeared to be red
– _______________= galaxies moving away from Earth
EVIDENCE FOR BIG BANG THEORY • ________________ BACKGROUND RADIATION
– Field of microwave radiation that comes from everywhere in the sky
– Discovered in 1965
– Scientists believe the microwave radiation found to be everywhere in the sky are dim remnants of radiation produced during the big bang.
QUIZ • How old is the universe believed to be? • Immediately after the big bang, did the universe expand
or contract? (is it still doing this today?)
• What force pulled atoms together as well as gas and dust to form stars and galaxies?
• What are the two pieces of evidence for the big bang theory?
• What does Hubble mean by a “red shift”?
STARS
• Star – huge spheres of very hot plasma that give off ________________and other types of radiation – The sun is our largest star – much closer to earth than
any other star
• Light-year – used to describe distances in space – One light-year is the distance light travels in one
___________ – One light-year = 9.5 trillion km/year
STAR FORMATION • Most stars begin as ______________, with
clouds of gas and dust mainly containing hydrogen and helium
• Hydrogen and helium are pulled together by ___________________
• The gravitational pull creates very high pressure and very high temperatures causing nuclear ______________ to begin which converts matter into energy – Stars give off this energy as heat, light, and other
forms of electromagnetic radiation
STAR CLASSIFICATION - BRIGHTNESS
• Stars are classified by their:
– Color
– Size
– Brightness
– Mass
STAR CLASSIFICATION – COLOR AND TEMPERATURE
• COLOR OF A STAR DETERMINES THE _____________________________ OF A STAR!!! – This is because the temperature of a star determines
the colors of light it gives off
– The hotter the star, the ____________ it appears
– The cooler the star, the ____________ it appears • Our sun is a moderately cool star, it gives off mostly yellow
light
– Temperature also affects __________________ • Hotter stars give off more intense light than cooler stars
STAR CLASSIFICATION - BRIGHTNESS
• BRIGHTNESS – _______________________
• Stars that are far away appear dimmer than closer stars that are the same size and temp.
– _______________________ • Cooler stars appear dimmer than hotter stars that are
the same size and distance from Earth
– _________________ • Small stars appear dimmer than larger stars that are the
same temp. and distance from Earth
HERTZSPRUNG – RUSSELL DIAGRAM
• _____________________ – Shows how the temperature and brightness of a star
are related – Graphs ____________________ vs. absolute
magnitude – Use to learn how stars change as they ___________
– As stars age and pass through different stages in their
life cycles, their positions on the diagram change – Most stars appear on a diagonal line in the diagram
called the __________________________
QUIZ • What is a light-year?
• Stars consist of what two elements that allow nuclear
fusion to occur?
• The color of a star tells you what about the star?
• What 3 factors affect the brightness of a star?
• What does an H-R diagram show you about a star?
• On what part of an H-R diagram is the sun found?
GALAXIES
• Galaxy – group of _________________ of individual stars, star, systems, star clusters, dust and gas bound together by gravity – More than ____________ billion galaxies in the
universe – The closest galaxy to Earth is millions of light years
away – Galaxies are moving _______________ from Earth
(Red Shift) • Galaxies that are farther away have a greater red shift
GALAXIES
• Galaxies are classified based on:
– Size
– Shape
• 3 main types:
– Spiral
– Elliptical
– irregular
______________ – have spiral arms of gas, dust, and stars
______________ – contain little gas or dust and have round or oval shapes
________________ – do not have any particular shape
OUR GALAXY! THE MILKY WAY
• ________________ galaxy
• More than 100 billion stars
• Diameter more than 100,000 light years
• At the center is a bulge of stars, and then spiral arms of gas, dust, and young stars
QUIZ
• How many galaxies are believed to be in our universe?
• Do galaxies experience a “red shift” or a “blue shift”?
• How are galaxies classified?
• What are the 3 types of galaxies?
• What type of galaxy is the our galaxy? What is its name?