Transcript ISP 205: Visions of the Universe

Welcome To Astronomy 110
• Instructor : Thomas Dixon
– Email : [email protected]
– http://www.ifa.hawaii.edu/~dixon/courses/astro110-summer-2011.htm
– For course guide, class schedule and lectures.
•
•
•
•
•
Course Time: MTWRF, 1030-1145am
Room: WAT 112
Course CRN : 90327
Duration: 07/05-08/12
The final exam will be in the final class of the session.
Copyright © 2012 Pearson Education, Inc.
Welcome To Astronomy 110
• Office Hours
– Immediately after classes … see me at the end class to arrange.
• Required Materials
– Lecture-Tutorials for Introductory Astronomy, 2nd edition, Edward
E. Prather et al.
– The Essential Cosmic Perspective Bennett (comes with bundled
material at UH Manoa bookstore).
– MasteringAstronomy.com access kit (comes bundled with the
textbook at the bookstore, or you can sign up on-line with your
credit card.)
Copyright © 2012 Pearson Education, Inc.
Typical Class Format
• A lecture with interactive questions and discussion.
• Followed by a tutorial, using
– ‘Lecture-Tutorials for Introductory Astronomy, 2nd edition.,
Edward E. Prather et al.’
– So you must buy the 2nd edition of this book ASAP.
– You will be working in pairs when you do the tutorial exercises.
– But I will provide assistance if needed.
– The answers you write in the tutorial book will become your text
book … Use it for revision.
– Many exam questions will be similar to those in this book.
Copyright © 2012 Pearson Education, Inc.
Course Assessment
• Homework average 20%.
– Short homeworks twice per week.
– No late homework accepted.
• Student Projects 20% (see course web site).
• Class Participation Credit 10%.
– Sign-in before each class starts.
• Exams based on Lectures, homeworks, class questions and
lecture tutorials.
–
–
–
–
First Mid-term 10%.
Second Mid-term 10%.
Final Exam 30%.
Exams will usually have some extra credit questions.
• You will not be graded on a curve.
Copyright © 2012 Pearson Education, Inc.
How to succeed in this course
• Come to class.
– We will be doing exam questions almost everyday in class.
• Read the text book as we go.
• Do the questions in the tutorial book.
– Also, try tutorials on the mastering astronomy website.
• Work in pairs\groups.
– But remember whatever you submit must be in your own words.
• If you have a course related problem, let me know ASAP.
• http://www.dartmouth.edu/~acskills/success/index.html
– You may find this site useful to assess how you learn.
Copyright © 2012 Pearson Education, Inc.
Some Course Topics
•
•
•
•
•
•
•
•
•
•
The Sun.
Phases of the Moon and lunar eclipses.
The solar system and its formation.
Star birth and death.
Black holes.
Galaxy formation.
The structure of the Universe.
The big bang.
Planets around other stars.
The search for ET.
Copyright © 2012 Pearson Education, Inc.
Our Place in the Universe
Copyright © 2012 Pearson Education, Inc.
What is our place in the universe?
Our “cosmic address”
Copyright © 2012 Pearson Education, Inc.
Star
A large, glowing ball of gas that generates heat and
light through nuclear fusion
Copyright © 2012 Pearson Education, Inc.
Planet
Mars
Uranus
A moderately large object that orbits a star; it
shines by reflected light. Planets may be rocky,
icy, or gaseous in composition.
Copyright © 2012 Pearson Education, Inc.
Moon (or satellite)
An object that orbits
a planet
Ganymede (orbits Jupiter)
Copyright © 2012 Pearson Education, Inc.
Asteroid
A relatively small
and rocky object
that orbits a star
Computer model from RADAR Measurements
Copyright © 2012 Pearson Education, Inc.
Comet
A relatively
small and icy
object that
orbits a star
Copyright © 2012 Pearson Education, Inc.
Solar (Star) System
A star and all the material that orbits
it, including its planets and moons
Copyright © 2012 Pearson Education, Inc.
Nebula
An interstellar cloud
of gas and/or dust
Copyright © 2012 Pearson Education, Inc.
Galaxy
A great island of stars in space, all held
together by gravity and orbiting a
common center
M31, theM31,
Great
theGalaxy
great galaxy in
in AndromedaAndromeda
Copyright © 2012 Pearson Education, Inc.
Universe
The sum total of all matter and energy;
that is, everything within and between
all galaxies
Copyright © 2012 Pearson Education, Inc.
How did we come to be?
Copyright © 2012 Pearson Education, Inc.
How did we come to be?
Copyright © 2012 Pearson Education, Inc.
How did we come to be?
Copyright © 2012 Pearson Education, Inc.
How did we come to be?
Copyright © 2012 Pearson Education, Inc.
How can we know what the universe was
like in the past?
• Light travels at a finite speed (300,000 km/s).
Destination
Light travel time
Moon
1 second
Sun
8 minutes
Sirius
8 years
Andromeda Galaxy
2.5 million years
• Thus, we see objects as they were in the past:
The farther away we look in distance,
the further back we look in time.
Copyright © 2012 Pearson Education, Inc.
Definition: Light-Year
• The distance light can travel in 1 year
• About 10 trillion kilometers (6 trillion
miles)
Copyright © 2012 Pearson Education, Inc.
• At great distances, we see objects as they were
when the universe was much younger.
Copyright © 2012 Pearson Education, Inc.
Example:
This photo shows the Andromeda Galaxy.
Question: When will we be able to see Andromeda as it is now?
A. Never.
B. 2.5 million years from
now.
C. Today.
D. There is no way to know.
Copyright © 2012 Pearson Education, Inc.
Put these objects in the correct
order, from nearest to farthest
from Earth:
A.
B.
C.
D.
The Moon, Mars, the Sun, the nearest stars, Pluto
The Moon, Mars, the Sun, Pluto, the nearest stars
The Moon, the Sun, Mars, Pluto, the nearest stars
Mars, the Moon, the Sun, the nearest stars, Pluto
Copyright © 2012 Pearson Education, Inc.
Which is farther, the distance from San
Francisco to Los Angeles, or the
distance from you to the space shuttle
if the shuttle passes directly overhead?
A. San Francisco – LA is further
B. The space shuttle is further
Copyright © 2012 Pearson Education, Inc.
Put these objects in the correct
order, from nearest to farthest
from Earth:
A. The Sun, the Milky Way, Sirius, Jupiter, the Andromeda
galaxy
B. The Sun, Sirius, Jupiter, the Andromeda galaxy, the Milky
Way
C. The Sun, Jupiter, Sirius, the Milky Way, the Andromeda
galaxy
D. Jupiter, the Sun, Sirius, the Milky Way, the Andromeda
galaxy
Copyright © 2012 Pearson Education, Inc.
Can we see the entire universe?
Copyright © 2012 Pearson Education, Inc.
Thought Question
Why can’t we see a galaxy 15 billion light-years
away?
(Assume the universe is 14 billion years old.)
A. No galaxies exist at such a great distance.
B. Galaxies may exist at that distance, but their
light would be too faint for our telescopes to see.
C. Looking 15 billion light-years away means
looking to a time before the universe existed.
Copyright © 2012 Pearson Education, Inc.
Let’s reduce the size of the solar system by a factor of
10 billion; the Sun is now the size of a large grapefruit
(14 cm diameter).
How big is Earth on this scale?
A.
B.
C.
D.
an atom
the tip of a ballpoint pen
a marble
a golf ball
Copyright © 2012 Pearson Education, Inc.
The scale of the solar system
• On a 1-to-10 billion
scale:
— Sun is the size of a
large grapefruit (14
centimeters).
— Earth is the size of a
tip of a ballpoint pen,
15 meters away.
Relative Distance of the Nearest Star
Copyright © 2012 Pearson Education, Inc.
Scales and Sizes In Astronomy
• Mercury’s distance from the Sun.
• Is about half the Sun-Earth distance.
• It is half and Astronomical Unit.
• The star Sirius is about twice as massive as the Sun
• We say it has a mass of two solar masses.
• Sirius is about 25 times more luminous than the Sun.
• We say it has a luminosity of twenty-five solar luminosities.
Copyright © 2012 Pearson Education, Inc.
How far away are the stars?
On our 1-to-10 billion scale, it’s just a few minutes’
walk to Pluto.
How far would you have to walk to reach Star?
A.
B.
C.
D.
1 mile
10 miles
100 miles
the distance across the United States (2500
miles)
Copyright © 2012 Pearson Education, Inc.
How big is the Milky Way Galaxy?
The Milky Way has
about 100 billion
stars.
On the same 1-to-10
billion scale…
The Size of the Milky Way
Copyright © 2012 Pearson Education, Inc.
Thought Question
Suppose you tried to count the more than 100 billion
stars in our galaxy, at a rate of one per second…
How long would it take you?
A. a few weeks
B. a few months
C. a few years
D. a few thousand years
Copyright © 2012 Pearson Education, Inc.
How big is the universe?
• The Milky Way is one of about 100 billion galaxies.
• 1011 stars/galaxy  1011 galaxies = 1022 stars
It has as many stars as grains of (dry) sand on all Earth’s beaches.
Copyright © 2012 Pearson Education, Inc.
Tutorial
• Now work on the Sun Size Tutorial.
• Page 105-107.
Copyright © 2012 Pearson Education, Inc.
Summary
• A light year is a measure of distance (it is
NOT a time).
• When we observe distant objects we see
them as they were in the past.
• 1 Astronomical Unit is the average EarthSun distance.
Copyright © 2012 Pearson Education, Inc.