Introduction to the Universe
Related Goals
• Appreciating science in general, and astronomy in
specific.
• Understanding how knowledge is gained and be
critical of what you see and hear. You will begin to ask
“How can we test that?” when forming hypotheses or
“How do we know that?” when reading new
information.
• Developing a working knowledge of the scientific
method and how to apply it to real world situations.
• Critically analyzing and evaluating information,
scientific or otherwise
Related Outcomes
• Learn some simple astronomical
nomenclature/terminology
• Learn about some problems astronomers and
astrophysicists are trying to solve, and understand the
methods scientists are using to try to solve these
problems.
• Develop a sense of what scientists know about the
overall universe, its constituents, and our location
Astro 25 extra outcomes that
we’ll touch on in chapter 1
• Understand the data that led to the
development of modern cosmology and
the Big Bang theory
• Evaluate the significance of the major
evidence in favor of the Big Bang theory.
• Illustrate how galaxies are distributed
through space.
• Discuss the evidence for Dark Matter and
Dark Energy.
Topics in this presentation
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Astronomical numbers
Light travel time
Composition of universe
Why the composition changes
– What causes the change?
• Sizes, distances, and ages
• Motions
• Expanding universe, how we measure age
Astronomical numbers
• 1 million = _________ = 10_. 1 million sec = ________
• 1 billion = __________= 10_ (aka. Giga or G). 1 giga-sec =
– _____________.
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1 light sec = ________________________________
= _________ = _____________. Almost to ________
1 light year = _______________________________
TRIVIA: 1 light year = ____________________.
Nearest star to Sun = _______________ away.
The Sun, all 8 planets are about _________ old.
– How many years is that?
• Universe & everything in it is _________ (some things
weren’t born at the beginning, so are younger)
Calif. School Science Standards for
Earth’s age & life development
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From California Science Standards, grade 6
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Students know that evidence from geologic layers
and radioactive dating indicates Earth is
approximately 4.6 billion years old and that life on
this planet has existed for more than 3 billion years.
Newest evidence: life probably started 3.5 billion years
ago, maybe even earlier (4 Gyr?).
And from the high school standards:
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Students know the evidence from Earth and moon
rocks indicates that the solar system was formed from a
nebular cloud of dust and gas approximately 4.6 billion
years ago.
•
The standards should include evidence from meteorites (space
rocks that landed on Earth)
Astronomers can detect a galaxy
that is 10 billion light-years away.
1. True
2. False
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Finding baby & senior citizen
galaxies
Talk to your neighbor for 1 minute and answer these:
• Where would astronomers need to look to find galaxies
in their earliest stages of life (babies)?
• Where would we find galaxies in their later stages
(senior citizens)?
Light years and observations
• FOR MORE HELP:
• See figure 1.5 on p. 9
• Lecture Tutorial workbook “Looking at
Distant Objects,” page 131.
California Elementary School
Science Standards for atoms
•
From California Science Standards,
grade 5
– Students know that each element is
made of one kind of atom and that the
elements are organized in the
periodic table by their chemical
properties.
Composition of the
Universe
• Stuff in universe (“______”)
• _______ matter ______________
______________
– _______ (often ____) ~___%
– _______ (often inert ____) ~__%
– ________________________
• __________________________________
__________________________________
• ______________________ are _________.
• __________________
– Matter ___________. Infer its existence
many ways. ______________________
• _____________________
– Energy ___________. Infer its existence
by _____________________________
_______. Book OMITS this from chap 1.
Another visual of universe’s
composition
Composition of the Universe
0.6%
4.4%
22%
Dark Energy
Dark Matter
"Normal Stuff" (baryons)
Neutrinos
73%
Normal matter
• Everything you know about is made of a few
______________________
– __________________________________________
• Most things are _______________________
– _______________________________________
• Science tells us right after the Big Bang, the
universe ________________________:
– ______________________________________
– TINY bit of 1-2 more.
• Where did everything else come from?
• Book calls it “_________”. See pages 6-7.
• Only __________________________. But that’s
enough to ______________________, luckily.
Calif. Elementary School Science
Standards for atoms & compounds
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From California Science Standards, grade 8
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Students know the structure of the atom and
know it is composed of protons, neutrons,
and electrons.
Students know that compounds are formed by
combining two or more different elements
and that compounds have properties that are
different from their constituent elements.
And from the high school standards:
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Students know the evidence indicating that all
elements with an atomic number greater
than that of lithium have been formed by
nuclear fusion in stars.
Ages of a few things
• When things formed:
– The Big Bang = ____________________ ago
– The Sun & Earth = ________________ ago
– The Milky Way galaxy = _____________ years ago
• See the calendar & discussion on page 14.
Sizes & Distances
• Planet order & sizes with hands…
• In the “Voyage” scale model, __________
– Sun is the size of ___________________
– ____________________________________
____________________________________
– ____________________________________
____________________________________
– Jupiter is …
– Pluto is …
– Nearest star is named …, size & dist …
– Size of Milky Way is …
• Light travel times to these objects…
California Elementary School
Science Standards for solar system
•
From California Science Standards, grade 5
– Students know the Sun, an average star, is
the central and largest body in the solar
system and is composed primarily of
hydrogen and helium.
– Students know the solar system includes
the planet Earth, the Moon, the Sun,
eight other planets and their satellites,
and smaller objects, such as asteroids
and comets.
•
Satellites = moons
California Elementary School
Science Standards for solar system
•
And from the high school standards:
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Students know the evidence indicating that the planets
are much closer to Earth than the stars are.
Students know the Sun is a typical star and is
powered by nuclear reactions, primarily the
fusion of hydrogen to form helium.
Students know the solar system is located in an outer edge
of the disc-shaped Milky Way galaxy, which spans 100,000
light years.
Students know galaxies are made of billions of stars and
comprise most of the visible mass of the universe.
•
Not true anymore. Most visible mass seems to be located in the
center of galaxy clusters.
Motions
• Daily motion – Earth’s rotation once per __
– Speed varies: ___ for Santa, __________________
• Yearly motion – Earth’s revolution once per __
– Distance: 1AU = ____
– Speed: average ~_____________mph
– Direction ________________________________.
• Sun ___________________________ 230 Myr
– 28,000 ly radius, speed ~500,000 mph
– Studying this motion  ______________________
• Galaxies moving relative to each other.
– _________________________________________
Do all continents on Earth take 24 hours to
make one circle around the Earth?
1. Yes
2. No
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Galaxies outside the Local Group
are moving:
1. Towards us
2. Away from us
3. Randomly towards & away
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Expanding universe means
“objects are getting _________”?
1. Further apart
2. Bigger
3. Both further apart and bigger
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Expanding universe
• Expansion refers to __________________________
– Objects don’t grow because …
• ___________________________________________
– Examples: ______________________________________.
• We see _______________________
• Speed away from us depends on ______________
– Objects ____________ are moving twice as fast
– Objects _____________ are moving _________________
• This rule is now called “____________________”
• Let’s see how __________________ works with cars
Car “expanding universe”
• Make a chart like the one I put on the board (next slide has
room)
• Car 1 is 60 miles away and travels 30 mph
• Car 2 is 120 miles away. How fast is it moving if
it follows Hubble’s Law?
• Car 3 is 240 miles away. How fast?
• How long since Car 1 left you?
• Car 2?
• Car 3?
• How old is the “car universe?”
• This is exactly what we see with galaxies,
except the time is _________ years.
Chart goes here
California Elementary School
Science Standards for astronomy
•
From California Science Standards, grade 8
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Students know galaxies are clusters of billions of stars and
may have different shapes.
Students know that the Sun is one of many stars in the Milky
Way galaxy and that stars may differ in size, temperature, and
color.
Students know how to use astronomical units and light years
as measures of distances between the Sun, stars, and
Earth.
Students know that stars are the source of light for all bright
objects in outer space and that the Moon and planets
shine by reflected sunlight, not by their own light.
•
–
(technically, Moon & planets shine by scattered light)
Students know the appearance, general composition, relative position
and size, and motion of objects in the solar system, including planets,
planetary satellites, comets, and asteroids.
Summary – chapter 1
•
•
•
•
Astronomical numbers
Light travel time
Composition of universe
Why the composition changes
– What causes the change?
• Sizes, distances, and ages
• Motions
• Expanding universe, how we measure age