Transcript class 1,S11

Welcome to AST 2002
I.
AST 2002H General Comments
Hard class, but also fun. Lots of resources:
a) Attend class
b) Keep up with lectures, quizzes, online resources
c) Office hours
d) Einstein Club (more on this later)
e) SARC tutors and workshops
f) [email protected]
II.
Online Resources
Mastering Astronomy comes with the new book.
Specific instructions from publisher. If questions about
Mastering Astronomy: [email protected]
AST 2002H General Comments
Mastering Astronomy:
Course ID: AST2002004S11
Free help available for Mastering Astronomy:
"virtual" office hours (times will be announced soon) with
AIM Screen Name ast2002help. Additionally, students may
use this email address: ([email protected]),
appointments to see students in person are also available.
AST 2002H General Comments (Cont.)
IV.
Class Mechanics:
• Syllabus has all the relevant information, READ IT!
• The Essential Cosmic Perspective (5th edition) by
Bennett .
– The Mastering Astronomy code comes with the book at the
UCF bookstore. MAKE SURE you get this code if you buy
the book elsewhere.
• 4 Exams: 3 in-class (Thursday Feb. 8, Thursday March17,
and Tuesday April 19), and a cumulative final (on Tuesday
April 26 at 1:00 PM)
• Grades: 100% exams, plus extra credit (see below)
IV. Class Mechanics: EXTRA CREDIT
• Participate in the Einstein Club
– To get extra credit you MUST complete 90% of the
assigned quizzes (you can miss no more than 1 quiz).
• If at end of semester the quiz requirement is
fulfilled, extra credit will be earned for several
activities:
– Attending a workshop at UCF's Student Academic
Resource Center (SARC, Phillips Hall Room 113)
BEFORE SPRING BREAK, can add 1%.
– Attending BEFORE SPRING BREAK a session with a
SARC astronomy tutor can add 1% extra credit.
– The total extra credit that can be earned is 3%, i.e., 1%
from the quizzes, 1% from the SARC workshop and 1%
from meeting with a SARC tutor (If you fulfill the
requirement of completing 85% of quizzes).
V.
Other:
a. Please turn off cell phones, never answer them in class
b. Do not be shy about asking questions in class, it
makes the lecture much more interesting
c. Seek help outside class (office hours, tutor at SARC)
d. Attendance is very important. Unannounced in-class
quizzes. Exams will be based on material covered in
class
e. Read chapters BEFORE CLASS, review and study
THAT DAY after class
f. Not a stargazing class, more like physics of the
universe
g. Course gets harder: get a good grade on the first exam
because its hard to recover later
Who cares about astronomy
anyway?
Outline of lecture 1 (Ch 1)
1.1 Our modern View of the Universe
Survey of the universe and powers of ten
1.2 The scale of the Universe
Astronomical distances
1.3 Spaceship Earth
Motions of Earth, Sun, Galaxies
1.1 Our Modern View of the Universe
Our goals for learning:
• What is our place in the universe?
• How did we come to be?
• How can we know what the universe was like in the
past?
• Can we see the entire universe?
Start with Earth-Moon and jump 100 times larger every slide
102
102
102
102
102
102
102
102
102
DISTANCE SCALES
• ASTRONOMICAL UNIT (AU):
– The average distance between the Earth and the
Sun.
• About 150 million km or 93 million miles
Sun.
1 AU
Earth
NOT TO SCALE!!!!
KUIPER BELT AND OORT CLOUD
PLUTO
NEPTUNE
URANUS
SATURN
JUPITER
ASTEROID BELT
MARS
EARTH
MERCURY
VENUS
A TOUR OF THE SOLAR
SYSTEM
NOT TO SCALE!!!!
10
20
30
40
URANUS
NEPTUNE
PLUTO
KUIPER BELT AND OORT CLOUD
5
SATURN
.4 .7 1.0 1.5
JUPITER
ASTEROID BELT
MARS
EARTH
Distance
(AU)
MERCURY
VENUS
A TOUR OF THE SOLAR
SYSTEM
DISTANCE SCALES
• LIGHT-YEAR (LY):
– The distance light can travel in one year.
• About 9.5 trillion km
– NOTE: this is a distance not a time!
– How far is the nearest star?
DISTANCE SCALES
• LIGHT-YEAR (LY):
– The distance light can travel in one year.
• About 9.5 trillion km
– NOTE: this is a distance not a time!
– How far is the nearest star? 4.3 Ly
WRITING NUMBERS IN
SCIENTIFIC NOTATION
CONVENTIONAL
SCIENTIFIC NOTATION
341,000
3.41 X 105
0.0000049
4.90 X 10-6
234,000,000
2.34 X 108
0.0134
1.34 X 10-2
1.1 Our Modern View of the Universe
Our goals for learning:
• What is our place in the universe?
We are on a planet, orbiting a star, in a galaxy
(which is a member of the Local Group of galaxies in the
Local Supercluster)
• How did we come to be?
• How can we know what the universe was like in the past?
• Can we see the entire universe?
STAR
A large, glowing ball of gas that generates heat
and light through nuclear fusion
PLANET
A moderately large object which orbits a star;
it shines by reflected light. Planets may be
rocky, icy, or gaseous in composition.
PLANET
What about Pluto?
What about objects larger than Pluto that
have been discovered? What about
asteroids?
The definition of a planet is not so clear
(it was much easier for the ancient
Greeks….for them a planet was a star that
moved and there were 5 of them)
MOON
An object which
orbits a planet.
ASTEROID
A relatively small
and rocky object
which orbits a star.
COMET
A relatively
small and icy
object which
orbits a star.
SOLAR (STAR) SYSTEM
A star and all the material which orbits it,
including its planets and moons
NEBULA
An interstellar cloud
of gas and/or dust
GALAXY
A great island of stars in space, all held
together by gravity and orbiting a
common center
THE UNIVERSE
The sum total of all matter and energy;
that is, everything within and between
all galaxies
AGE OF UNIVERSE
Age of Universe: about 14 billion years
Age of Solar System: about 4.6 billon years
Cosmic Calendar: see details in book
1.1 Our Modern View of the Universe
Our goals for learning:
• What is our place in the universe?
We are on a planet, orbiting a star, in a galaxy (which is a member
of the Local Group of galaxies in the Local Supercluster).
• How did we come to be?
—The matter in our bodies came from the Big Bang, which
produced hydrogen and helium.
—All other elements were constructed from H and He in stars
and then recycled into new star systems, including our solar
system.
• How can we know what the universe was like in the past?
• Can we see the entire universe?
Where do we come from?
• The first (and simplest) atoms were created during
the Big Bang.
• More complex atoms were created in stars.
• When the star dies, they are expelled into space….
to form new stars and planets!
Most of the atoms in our
bodies were created in
the core of a star!
SPEED OF LIGHT
• The speed of light in the vacuum of space is
constant! All light travels the same speed!
c = speed of light
= 290,000,000 m/sec
= 2.9 x 108 m/sec
= 290,000 km/sec
Looking back in time
• Light, although fast, travels at a finite speed.
• It takes:
– 8 minutes to reach us from the Sun
– 8 years to reach us from Sirius (8 light-years away)
– 1,500 years to reach us from the Orion Nebula
• The farther out we look into the Universe, the farther
back in time we see!
1.1 Our Modern View of the Universe
Our goals for learning:
•
What is our place in the universe?
We are on a planet, orbiting a star, in a galaxy (which is a member of the Local Group of galaxies in the Local
Supercluster).
•
How did we come to be?
— The matter in our bodies came from the Big Bang, which produced hydrogen and helium.
— All other elements were constructed from H and He in stars and then recycled into new star systems,
including our solar system.
• How can we know what the universe was like in
the past?
—When we look to great distances we are seeing events that
happened long ago because light travels at a finite speed.
• Can we see the entire universe?
1.1 Our Modern View of the Universe
Our goals for learning:
•
What is our place in the universe?
We are on a planet, orbiting a star, in a galaxy (which is a member of the Local Group of galaxies in the Local
Supercluster).
•
How did we come to be?
— The matter in our bodies came from the Big Bang, which produced hydrogen and helium.
— All other elements were constructed from H and He in stars and then recycled into new star systems,
including our solar system.
• How can we know what the universe was like in
the past?
—When we look to great distances we are seeing events that
happened long ago because light travels at a finite speed.
• Can we see the entire universe?
– Nope!
1.1 Our Modern View of the Universe
Our goals for learning:
•
What is our place in the universe?
We are on a planet, orbiting a star, in a galaxy (which is a member of the Local Group of galaxies in the Local
Supercluster).
•
How did we come to be?
— The matter in our bodies came from the Big Bang, which produced hydrogen and helium.
— All other elements were constructed from H and He in stars and then recycled into new star systems,
including our solar system.
• How can we know what the universe was like in the past?
— When we look to great distances we are seeing events that happened long ago because light
travels at a finite speed.
• Can we see the entire universe?
—No, the observable portion of the universe is about 14 billion
light-years in radius because the universe is about 14 billion
years old. ALSO (not in Ch. 1 of the book), we can “see”
only about 4% of the universe, 96% is made of “dark matter”
and “dark energy”.
What have we learned?
• How is Earth moving in our solar system?
— It rotates on its axis once a day and orbits the
Sun at a distance of 1 AU = 150 million km
• How is our solar system moving in the Milky
Way Galaxy?
— Stars in the Local Neighborhood move
randomly relative to one another and orbit
the center of the Milky Way in about 230
million years
What have we learned?
• How do galaxies move within the universe?
— All galaxies beyond the Local Group are
moving away from us with expansion of the
universe: the more distant they are, the faster
they’re moving
• Are we ever sitting still?
— No!