Copyright © 2012 Pearson Education, Inc. Welcome To Astronomy 110 Instructor : Thomas Dixon...

Copyright © 2012 Pearson Education, Inc.

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.


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.)


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.


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.


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.


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.


Our Place in the Universe


What is our place in the universe?

Our “cosmic address”


A large, glowing ball of gas that generates heat and light through nuclear fusion

Star


Planet

A moderately large object that orbits a star; it shines by reflected light. Planets may be rocky,

icy, or gaseous in composition.

UranusMars


Moon (or satellite)

An object that orbits a planet

Ganymede (orbits Jupiter)


Asteroid

A relatively small and rocky object that orbits a star

Computer model from RADAR Measurements


Comet

A relatively small and icy object that orbits a star


Solar (Star) System

A star and all the material that orbits it, including its planets and moons


Nebula

An interstellar cloud of gas and/or dust


GalaxyA great island of stars in space, all held

together by gravity and orbiting a common center

M31, the Great Galaxy in Andromeda

M31, the great galaxy in Andromeda


Universe

The sum total of all matter and energy; that is, everything within and between

all galaxies


How did we come to be?


How can we know what the universe was like in the past?

• Light travels at a finite speed (300,000 km/s).

• Thus, we see objects as they were in the past:The farther away we look in distance,

the further back we look in time.

Destination Light travel time

Moon 1 second

Sun 8 minutes

Sirius 8 years

Andromeda Galaxy 2.5 million years


Definition: Light-Year

• The distance light can travel in 1 year

• About 10 trillion kilometers (6 trillion miles)


• At great distances, we see objects as they were when the universe was much younger.


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.


Put these objects in the correct order, from nearest to farthest

from Earth:A. The Moon, Mars, the Sun, the nearest stars, PlutoB. The Moon, Mars, the Sun, Pluto, the nearest starsC. The Moon, the Sun, Mars, Pluto, the nearest starsD. Mars, the Moon, the Sun, the nearest stars, Pluto


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


Put these objects in the correct order, from nearest to farthest

from Earth:A. The Sun, the Milky Way, Sirius, Jupiter, the Andromeda

galaxyB. The Sun, Sirius, Jupiter, the Andromeda galaxy, the

Milky WayC. The Sun, Jupiter, Sirius, the Milky Way, the Andromeda

galaxyD. Jupiter, the Sun, Sirius, the Milky Way, the Andromeda

galaxy


Can we see the entire universe?


Thought Question

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.

Why can’t we see a galaxy 15 billion light-years away? (Assume the universe is 14 billion years old.)


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. an atom

B. the tip of a ballpoint pen

C. a marble

D. a golf ball


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


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.


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. 1 mileB. 10 milesC. 100 milesD. the distance across the United States (2500

miles)


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


Thought Question

How long would it take you?

A. a few weeks

B. a few months

C. a few years

D. a few thousand years

Suppose you tried to count the more than 100 billion stars in our galaxy, at a rate of one per second…


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.


Tutorial

• Now work on the Sun Size Tutorial.

• Page 105-107.


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 Earth-Sun distance.

Copyright © 2012 Pearson Education, Inc. Welcome To Astronomy 110 Instructor : Thomas Dixon...

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