Martin D. Weinberg UMass Astronomy...

93
Lec 01 09/04/12 – slide 1 A100–Exploring the Universe: Introduction Martin D. Weinberg UMass Astronomy [email protected] September 4, 2012

Transcript of Martin D. Weinberg UMass Astronomy...

Page 1: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Lec 01 09/04/12 – slide 1

A100–Exploring the Universe: Introduction

Martin D. Weinberg

UMass Astronomy

[email protected]

September 4, 2012

Page 2: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Overview

⊲ Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 2

What is Astronomy?

⊲ Story of our understanding of the Universe

⊲ By the end of the course, we will have traveled

through the solar system, the Galaxy, clusters of

galaxies to the beginning of the Universe.

Page 3: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Overview

⊲ Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 2

What is Astronomy?

⊲ Story of our understanding of the Universe

⊲ By the end of the course, we will have traveled

through the solar system, the Galaxy, clusters of

galaxies to the beginning of the Universe.

Objectives

⊲ Organization of the Universe

⊲ Principal components that create this organization

⊲ Scientific method: how we try overcome human

perceptual limitations to figure this out

Page 4: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Earth in the Universe

Overview

⊲ Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 3

Page 5: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Earth in the Universe

Overview

⊲ Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 3

104 km

Page 6: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Earth in the Universe

Overview

⊲ Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 3

104 km

1010 km

Page 7: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Earth in the Universe

Overview

⊲ Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 3

104 km

1010 km

1018 km

Page 8: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Earth in the Universe

Overview

⊲ Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 3

104 km

1010 km

1018 km

3× 1019 km

Page 9: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Earth in the Universe

Overview

⊲ Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 3

104 km

1010 km

1018 km

3× 1019 km

1021 km

Page 10: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scale of the Universe

Overview

Earth in context

⊲Scale of theUniverse

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 4

Sun = basketball

Earth = marble at a few hundred feet

Nearest star = about 10000 miles away (Tokyo)

Center of the Milky Way = 10000 times the nearest star

or 100,000,000 miles away

Nearest Galaxy = 1000 times distance to center of Milky

Way 100,000,000,000 miles away

Page 11: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Human Biases

Overview

Earth in context

Scale of the Universe

⊲ Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 5

Human biases

Cosmic length scales—very large compared to human

sizen

Cosmic time scales—very long compared to human

lifetime

Cosmic events at many wavelengths—humans have

limited sensitivity to the electromagnetic spectrum

Page 12: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Looking into the past

Overview

Earth in context

Scale of the Universe

Human Biases

⊲ Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 6

What was the Universe like in the past?

Destination Light travel time

Moon 1 second

Sun 8 minutes

Sirius 8 years

Andromeda Galaxy 2.5 million years

Page 13: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Looking into the past

Overview

Earth in context

Scale of the Universe

Human Biases

⊲ Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 6

What was the Universe like in the past?

Destination Light travel time

Moon 1 second

Sun 8 minutes

Sirius 8 years

Andromeda Galaxy 2.5 million years

Observing at large distances is looking back in time!!

Page 14: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Looking into the past

Overview

Earth in context

Scale of the Universe

Human Biases

⊲ Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 6

What was the Universe like in the past?

Destination Light travel time

Moon 1 second

Sun 8 minutes

Sirius 8 years

Andromeda Galaxy 2.5 million years

This is known as the “Space-time continuum”

Page 15: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Light-Year

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

⊲ The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 7

The distance light can travel in one year

About 10 trillion km (6 trillion miles)

Page 16: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Light-Year

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

⊲ The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 7

The distance light can travel in one year

About 10 trillion km (6 trillion miles)

At great distances we see objects as they were when the

Universe was much younger

Page 17: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Light-Year

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

⊲ The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 7

The distance light can travel in one year

About 10 trillion km (6 trillion miles)

At great distances we see objects as they were when the

Universe was much younger

Page 18: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Light-Year

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

⊲ The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 7

The distance light can travel in one year

About 10 trillion km (6 trillion miles)

At great distances we see objects as they were when the

Universe was much younger

Question: can we see the entire Universe?

Page 19: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Course

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

⊲ The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 8

Three encompassing topics

⊲ Motions, Light and Gravity

⊲ Stars

⊲ Galaxies & Cosmology

Page 20: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Course

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

⊲ The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 8

Three encompassing topics

⊲ Motions, Light and Gravity

⊲ Stars

⊲ Galaxies & Cosmology

Text book: The Cosmic Perspective: Stars, Galaxies and

Cosmology, 6e, by Bennett et al.

Page 21: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Course

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

⊲ The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 8

Three encompassing topics

⊲ Motions, Light and Gravity

⊲ Stars

⊲ Galaxies & Cosmology

Text book: The Cosmic Perspective: Stars, Galaxies and

Cosmology, 6e, by Bennett et al.

Attendance is optional, but you are responsible for topics

covered in class whether you attend or not.

Page 22: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Course

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

⊲ The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 8

Three encompassing topics

⊲ Motions, Light and Gravity

⊲ Stars

⊲ Galaxies & Cosmology

Text book: The Cosmic Perspective: Stars, Galaxies and

Cosmology, 6e, by Bennett et al.

Attendance is optional, but you are responsible for topics

covered in class whether you attend or not.

My role is to help you understand. Please ask questions!!

Page 23: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

The Course

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

⊲ The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Lec 01 09/04/12 – slide 8

Three encompassing topics

⊲ Motions, Light and Gravity

⊲ Stars

⊲ Galaxies & Cosmology

Text book: The Cosmic Perspective: Stars, Galaxies and

Cosmology, 6e, by Bennett et al.

Attendance is optional, but you are responsible for topics

covered in class whether you attend or not.

My role is to help you understand. Please ask questions!!

Web site:

http://www.astro.umass.edu/~weinberg/a100

Page 24: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Requirements

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

⊲ Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 9

Reading: Assignments in the text for each class will be

given in preceding class and are required. The relevant

chapters are also listed in the Syllabus by subject.

⊲ You should expect to spend about 3 hours out of

class for every one hour of class time.

⊲ Effort = Final Grade

Page 25: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Requirements

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

⊲ Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 10

Exams: Three in-class one-hour exams and a final exam.

Of the four, I will drop you lowest score. The exams will

be multiple choice.

The exam dates are in the syllabus. They will only

change if the University is closed (e.g. snow day). In that

case, the exam will be held at the next class meeting.

Please bring a #2 pencil to each exam!

Page 26: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

A100 structure: lecture + lab

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

⊲ A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 11

A100: four credits with a lab

⊲ The lecture counts for 75% of your total grade

⊲ The lab counts for 25% of your total grade

Your lecture grade:

score =Your points

Total points× 100

Your course grade:

score = Lecture grade × 0.75 + Lab grade × 0.25

Page 27: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Lab info

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

⊲ A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 12

Tom Burbine runs the labs, not me . . .

The first lab meeting for the Wednesday lab will be this

Wed. (5th) from 4:40PM - 5:30PM in Hasbrouck 20

The first lab meeting for the Monday lab will be next

Mon. (10th) from 4:40PM - 5:30PM in Hasbrouck 20

After the orientation meeting, labs will be scheduled

every other week

Most of the assignments will be submitted on the Lab’s

Spark page

Here is the website for the lab:

http://blogs.umass.edu/astron100-tburbine/

Page 28: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Policies

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

⊲ Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 13

Makeup exam policy: Following the University

guidelines, makeup exams will be given only for

documented medical or family emergencies or by prior

arrangement.

Homework: There will be (roughly) weekly homework

assignments worth 25% of the total lecture score.

We will using www.masteringastronomy.com, an online

assignment system.

Page 29: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Policies

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

⊲ Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 14

Extra credit: At the end of each class, you may pass in a

sheet of paper with your name, UMass ID and

1. Brief description of an idea or topic from the day

that you found particular interesting

2. Your top question from the day’s class

1/2 credit for each. Over the entire semester, this is

worth up to 5% to your final score.

Some of the homework assignments will have additional

questions that count for extra credit.

There are no other forms of extra credit.

Page 30: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Grades

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

⊲ Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 15

Grades will be assigned on a modified straight scale.

Scores will be adjusted upward if the exam is too hard.

92.5% A

90% A-

87.5% B+

82.5% B

80% B-

77.5% C+

72.5% C

70% C

67.5% D+

60% D

3 exams 37.5%

Online homework 18.75%

In-class feedback 3.75%

Lab score 25%

Academic Honesty is expected of all scientists, and also

of all students of science.

Page 31: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

MasteringAstronomy

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

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Scientific Notation

Light-year in km

Metric Prefixes

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Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 16

Interactive, online homework and study system (see your

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MasteringAstronomy

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

⊲ MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 16

Interactive, online homework and study system (see your

handout)

You must register using the access packet that comes

with your textbook

Page 55: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

MasteringAstronomy: grading

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

⊲ MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 17

The assignments untimed. You may stop in the middle,

go back later, etc.

The system offers you hints, if you want them. Not using

hints is worth 2% bonus credit.

If you give an incorrect response, in many cases, you will

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Page 56: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 18

104 km

1010 km

1018 km

3× 1019 km

1021 km

Page 57: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 19

The numbers encountered in this class are astronomical:

The nearest star is 41,000,000,000,000 kilometers away

The mass of the sun is

2,000,000,000,000,000,000,000,000,000,000,000 grams

Scientists have devised a more compact notation for dealing

with such numbers called scientific notation.

Page 58: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 20

41,000,000,000,000 kilometers

2,000,000,000,000,000,000,000,000,000,000,000 grams

There are really only two important parts to each of the

numbers:

1. The leading digits – which establish the precision of the

number itself

2. The number of digits – which sets the size or magnitude

of the number

In Scientific notation:

4.1×1013 and 2.0×1033

Page 59: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 21

The “×” is, as it appears, a multiplication:

102 = 10 × 10 = 100

103 = 10 × 10 × 10 = 1,000

104 = 10 × 10 × 10 × 10 = 10,000

105 = 10 × 10 × 10 × 10 × 10 = 100,000

106 = 10 × 10 × 10 × 10 × 10 × 10 = 1,000,000

so 4.5×104 = 4.5 × 10 × 10 × 10 × 10 = 45,000.

Page 60: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 22

Counting zeros and moving the decimal place is a convenient

way of carrying out the multiplication by powers of ten

Example:

Want: 103 × 105

103 × 105 = 10× 10× 10 × 10× 10× 10× 10× 10 = 108

The result of that long string of multiplication is that we add

the exponents of the 10’s: 3+5=8

Page 61: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 23

Addition a bit more tricky:

103+105 = 10×10×10 + 10×10×10×10×10 = 1.01×105

Page 62: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 23

Addition a bit more tricky:

103+105 = 10×10×10 + 10×10×10×10×10 = 1.01×105

or

1, 000 + 100, 000 = 101, 000 = 1.01× 105

Page 63: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Scientific Notation

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

⊲ScientificNotation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 23

Addition a bit more tricky:

103+105 = 10×10×10 + 10×10×10×10×10 = 1.01×105

or

1, 000 + 100, 000 = 101, 000 = 1.01× 105

or

0.01× 105 + 1.0× 105 = 1.01× 105

Rule: add the prefix (mantissa) when power of ten (exponent)

for the addends is the same

Page 64: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Light-year in km

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

⊲ Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 24

1 light-year = (speed of light)× (1 year)

= 300, 000km

365days

1 year×

24hr

1day×

60min

1hour×

60 s

1min

Page 65: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Light-year in km

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

⊲ Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 24

1 light-year = (speed of light)× (1 year)

= 300, 000km

✁s×

365✟✟✟days

1✘✘✘year×

24✚✚hr

1✚✚day

×

60✟✟✟min

1✘✘✘hour×

60 ✁s

1✟✟✟min

Page 66: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Light-year in km

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

⊲ Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 24

1 light-year = (speed of light)× (1 year)

= 300, 000km

✁s×

365✟✟✟days

1✘✘✘year×

24✚✚hr

1✚✚day

×

60✟✟✟min

1✘✘✘hour×

60 ✁s

1✟✟✟min= 9, 460, 000, 000, 000 km

Page 67: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Light-year in km

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

⊲ Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 24

1 light-year = (speed of light)× (1 year)

= 300, 000km

✁s×

365✟✟✟days

1✘✘✘year×

24✚✚hr

1✚✚day

×

60✟✟✟min

1✘✘✘hour×

60 ✁s

1✟✟✟min= 9, 460, 000, 000, 000 km

= 9.46× 1012 km

Page 68: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Light-year in km

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

⊲ Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 24

1 light-year = (speed of light)× (1 year)

= 300, 000km

✁s×

365✟✟✟days

1✘✘✘year×

24✚✚hr

1✚✚day

×

60✟✟✟min

1✘✘✘hour×

60 ✁s

1✟✟✟min= 9, 460, 000, 000, 000 km

= 9.46× 1012 km

≈ 1013 km

Page 69: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Metric Prefixes

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

⊲ Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 25

10−15 femto-

10−12 pico-

10−9 nano-

10−6 micro-

10−3 milli-

10−2 centi-

10−1 deci-

10 deka-

102 hecto-

103 kilo-

106 mega-

109 giga-

1012 tera-

1015 peta-

Page 70: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Measuring distance

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

⊲Measuringdistance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 26

Distance in meters (m)

Page 71: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Energy Output

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

⊲ Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 27

Energy Source Total Energy (J)

Big Bang 1068

Radio galaxy 1055

Supernova 1046

Sunlight (1 y) 1034

Volcanic explosion 1019

H-bomb 1017

Thunderstorm 1015

Lightning flash 1010

Baseball pitch 102

Typing (per key) 10−2

Flea hop 10−7

Page 72: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Local motions

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

⊲ Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 28

Earth rotates: speed = 0.5 km/s = 1,700 km/hour =

1,000 miles/hour

Page 73: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Local motions

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

⊲ Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 28

Earth rotates: speed = 0.5 km/s = 1,700 km/hour =

1,000 miles/hour

Earth orbital speed (solar system) = 30 km/s = 170,000

km/hour = 67,000 miles/hour miles/hour

Page 74: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Local motions

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

⊲ Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 28

Earth rotates: speed = 0.5 km/s = 1,700 km/hour =

1,000 miles/hour

Earth orbital speed (solar system) = 30 km/s = 170,000

km/hour = 67,000 miles/hour miles/hour

Sun’s orbital speed (Galaxy) = 200 km/s = 450,000

miles/hour

Page 75: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Motions in the galaxy

Read: Chap 1 09/04/12 – slide 29

Page 76: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Dark Matter

Read: Chap 1 09/04/12 – slide 30

Page 77: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Expanding Universe

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

⊲ExpandingUniverse

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 31

Discovery by Edwin Hubble in 1929

All galaxies outside of our Local Group are moving away

from us

The more distant the galaxy, the faster it is moving

Nothing special about our location in the Universe

Page 78: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Expanding Universe

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

⊲ExpandingUniverse

Motions summary

Origin of theelements

Time scales

Read: Chap 1 09/04/12 – slide 31

Discovery by Edwin Hubble in 1929

All galaxies outside of our Local Group are moving away

from us

The more distant the galaxy, the faster it is moving

Nothing special about our location in the Universe

Conclusion: We live in an expanding Universe!

Page 79: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Expanding Universe

Read: Chap 1 09/04/12 – slide 32

Page 80: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Motions summary

Read: Chap 1 09/04/12 – slide 33

Page 81: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Origin of the elements

Read: Chap 1 09/04/12 – slide 34

Gas (mostly hydrogen) set-

tles in the disk of galaxies

This gas fragments into

dense knots, forms stars

The stars fuse hydrogen

into helium and heavier el-

ements, generating energy

The star explodes!

Galaxy: a huge “island” of stars

moving around a common center

and held together by gravity.

Page 82: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Origin of the elements

Read: Chap 1 09/04/12 – slide 34

Gas (mostly hydrogen) set-

tles in the disk of galaxies

This gas fragments into

dense knots, forms stars

The stars fuse hydrogen

into helium and heavier el-

ements, generating energy

The star explodes!

Nebula: an interstellar cloud of

dust and/or gas

Page 83: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Origin of the elements

Read: Chap 1 09/04/12 – slide 34

Gas (mostly hydrogen) set-

tles in the disk of galaxies

This gas fragments into

dense knots, forms stars

The stars fuse hydrogen

into helium and heavier el-

ements, generating energy

The star explodes!

Star: generates heat and light

through nuclear fusion

Page 84: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Origin of the elements

Read: Chap 1 09/04/12 – slide 34

Gas (mostly hydrogen) set-

tles in the disk of galaxies

This gas fragments into

dense knots, forms stars

The stars fuse hydrogen

into helium and heavier el-

ements, generating energy

The star explodes!

Supernova: fusion fuel ex-

hausted, the star explodes

Page 85: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Origin of the elements

Read: Chap 1 09/04/12 – slide 34

Gas (mostly hydrogen) set-

tles in the disk of galaxies

This gas fragments into

dense knots, forms stars

The stars fuse hydrogen

into helium and heavier el-

ements, generating energy

The star explodes!

Page 86: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Page 87: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Page 88: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Time for Uranus to orbit the Sun: 84 years

Page 89: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Time for Uranus to orbit the Sun: 84 years

Time for Sun to Orbit the Galaxy:

Time =2π × 28, 000 light years

200 km/s

Page 90: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Time for Uranus to orbit the Sun: 84 years

Time for Sun to Orbit the Galaxy:

Time =2π × 28, 000 light years

200 km/s

= 2π28, 000 light years

220 km/s×

9.46× 1012 km

1 light year×

1 year

3.15× 107 s

Page 91: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Time for Uranus to orbit the Sun: 84 years

Time for Sun to Orbit the Galaxy:

Time =2π × 28, 000 light years

200 km/s

= 2π28, 000✘✘✘✘✘✘

light years

220✘✘✘km/s×

9.46× 1012✟✟km

1✘✘✘✘✘light year×

1 year

3.15× 107 ✁s

= 2.4× 108 year = 240× 106 year

Page 92: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Time for Uranus to orbit the Sun: 84 years

Time for Sun to Orbit the Galaxy: 240 million years

Time for Milky Way to collide with Andromeda Galaxy:

10 billion years

Page 93: Martin D. Weinberg UMass Astronomy weinberg@astro.umassastro.umass.edu/~weinberg/a100/lectures/lec01.pdf⊲ Stars ⊲ Galaxies & Cosmology Text book: The Cosmic Perspective: Stars,

Time scales

Overview

Earth in context

Scale of the Universe

Human Biases

Back in time

The Light-Year

The Course

Requirements

A100 structure

Policies

Grades

MasteringAstronomy

Scientific Notation

Light-year in km

Metric Prefixes

Measuring distance

Energy Output

Local motions

Galactic motions

Dark Matter

Expanding Universe

Motions summary

Origin of theelements

⊲ Time scales

Read: Chap 1 09/04/12 – slide 35

Time for Earth to make one rotation: 1 day

Time for Earth to orbit the Sun: 1 year

Time for Uranus to orbit the Sun: 84 years

Time for Sun to Orbit the Galaxy: 240 million years

Time for Milky Way to collide with Andromeda Galaxy:

10 billion years

Time for light to get to us from the most distant galaxy:

14 billion years