copyright © 2015, w. w. norton & company prepared by lisa m. will, san diego city college...

38
Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding Our Universe SECOND EDITION Stacy Palen, Laura Kay, Brad Smith, and George Blumenthal

Upload: ariel-hutchinson

Post on 31-Dec-2015

216 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Copyright © 2015, W. W. Norton & Company

Prepared by Lisa M. Will, San Diego City College

Lecture SlidesCHAPTER 1: Thinking Like an Astronomer

Understanding Our UniverseSECOND EDITION

Stacy Palen, Laura Kay, Brad Smith, and George Blumenthal

Page 2: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

What is Astronomy?

Loosely translated – “finding patterns amongst the stars”

Modern definition – the study of the universe

Page 3: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

What is Astronomy?: Purpose

Astronomy seeks to understand:• Our place in the universe.

• Our connection to the universe.

• Our astronomical origins.

Page 4: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Universe: everything; the entirety of space and time Galaxy: a massive system of stars (and other stuff

such as interstellar gas and dust) that exists inside the universe

Solar system: a star and its surrounding planets, comets, asteroids, etc… that exists inside a galaxy

A Few Vocabulary Terms

Page 5: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Earth is a relatively small planet. Orbiting an ordinary star Orbiting a supermassive black

hole at the center of the Milky Way galaxy.

Our Place in the Universe: The Earth

Page 6: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

The Milky Way is a spiral galaxy. Contains 100 billion stars Just one of billions of galaxies In a universe that is 13.8 billion

years old

Our Place in the Universe: The Milky Way

Page 7: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Class Question: Which of the following ranks the

sizes of the listed objects in the correct order, from

smallest to largest?

A. Asteroid, Galaxy, Solar System, Universe

B. Solar System, Galaxy, Asteroid, Universe

C. Asteroid, Solar System, Galaxy, Universe

D. Universe, Galaxy, Asteroid, Solar System

Class Question

Page 8: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

The universe is huge! One of the biggest challenges in astronomy is

measuring the distance to stars and galaxies. We use the travel time of light to measure the vast

distances of the universe.

Our Place in the Universe: How Far Away

Page 9: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Speed of light = 300,000 km/s = 186,000 mi/s Cosmic speed limit! So fast it could travel around the Earth in 1/7 of a

second

Our Place in the Universe: Speed of Light

Page 10: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

A Light-year is a DISTANCE, NOT a TIME!

It’s the distance light travels in one year = 9.5 million million km=9,500,000,000,000 kmIn scientific notation, that’s 9.5 x 1012 km or 9.5 x 1015 m

Don’t believe me? Let’s take a little math break. It won’t hurt, really! Exponents: 10,000 = 10 to what power?0.01 = 10 to what power?

The speed of light is constant = 300,000 km/s = 3.0 x105 km/s So a light year is a distance = speed*time We know speed. We need time. How many seconds in a year?T(in year) = 365.25 days*24 hr/day * 3600 sec/hr = 3.16x107 sThus, distance of 1 light year = speed*time = 3.0 x105 km/s * 3.16x107 s = 9.5 x 1012 km . Yay!

Our Place in the Universe: Light-Year

Page 11: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe: Light-Year (Cont.)

Page 12: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe: Light-Year (Cont.)

Page 13: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe: Light-Year (Cont.)

Page 14: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe (Cont.)

Page 15: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe (Cont.)

Page 16: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe (Cont.)

Page 17: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Place in the Universe (Cont.)

Page 18: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Class Question

Which of the following is a distance?

A. 500 light-years

B. 500 years

Page 19: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Class Question

Which of the following is a time?

A. 500 light-years

B. 8.3 light-minutes

C. 4 hours

D. 2.5 light-hours

Page 20: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Astronomical Origins

Stars generate energy by nuclear fusion, creating heavier elements in the process.

Dying stars eject those elements into space.

New stars and planets (and humans) form.

WE ARE STARDUST!

Page 21: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Connection to the Universe

We study the universe from both the ground and in space.

We use telescopes, spacecraft, physics experiments, etc… to expand our understanding of the universe.

Page 22: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Connection to the Universe: Science

Science is a way of exploring the physical universe

through the scientific method.

The scientific method is a systematic way of testing

new ideas.

Page 23: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Scientific Method

Hypothesis: an idea that can explain a phenomenon. Theory: a hypothesis which tests have failed to

disprove. Physical law: theories that have become very well

tested and are of fundamental importance.

Page 24: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

The cosmological principle: The testable assumption that the same physical laws that apply here and now also apply everywhere and at all times.

Another way of thinking about it: “There is nothing special about our place in the universe.”

Our Connection to the Universe: The Cosmological Principle

Page 25: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Implications of Cosmological Principle

Our view from the Earth is not special or unique. On a large scale, the universe is the same

everywhere. Matter and energy obey the same physical laws

everywhere. We can learn about distant objects by studying

nearby ones.

Page 26: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Scientific Method

The scientific method works like this:

Idea Hypothesis Prediction Test

Page 27: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Scientific Method: Testing

Scientific theories must be testable and falsifiable. All scientific knowledge is conditional. Our

understanding can change due to additional experimental findings.

=> This is how science makes progress.

Page 28: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Existing, accepted ideas are subject to challenge via the scientific method.

All theories must ultimately agree with nature.

Scientific Method: Agreement with Nature

Page 29: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Class Question

Which of the following represents a scientific way

of looking at nature?

A. All ideas are equally valuable and should be equally respected.

B. Well-established ideas should never be checked or tested.

C. Nature informs us about the usefulness of our ideas.

Page 30: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Class Question

Which of the following is a valid scientific

Hypothesis?

A. Parts of the universe will never be discovered.

B. Stars generate energy by burning coal.

C. There are processes in nature that we will never understand.

Page 31: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Class Question

Do you agree with the following statement?

“Evolution cannot be correct because it is just

a theory.”

A. Yes

B. No

Page 32: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Connection to the Universe: Patterns in Nature

Science discovers patterns in nature. Most phenomena work regularly and predictably.

Page 33: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Connection to the Universe: Language of Patterns

Mathematics is the language of patterns.

It can describe and predict relationships, like the one between distance and time traveled during a car trip.

Page 34: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Mathematics can describe and predict phenomena like Earth’s seasons.

Mathematics is a tool to express relationships concisely.

Our Connection to the Universe: Language of Patterns (Contd.)

Page 35: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Our Connection to the Universe: Ancient Science

Astronomy is an ancient science.

Join the many humans who have thought about the universe.

Build understanding. Share with others.

Page 36: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Chapter Summary

Astronomy is the study of the universe. We use the scientific method and the language

of mathematics to help us understand:• Our place in the universe.

• Our connection to the universe.

• Our astronomical origins.

Page 37: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Nebraska Applet

Click the image to launch the Nebraska Applet(Requires an active Internet connection)

Lookback Time Simulator

Page 38: Copyright © 2015, W. W. Norton & Company Prepared by Lisa M. Will, San Diego City College Lecture Slides CHAPTER 1: Thinking Like an Astronomer Understanding

Copyright © 2015, W. W. Norton & Company

wwnpag.es/uou2

Prepared by Lisa M. Will, San Diego City College

CHAPTER 1: Thinking Like an Astronomer

This concludes the Lecture slides for

Understanding Our UniverseSECOND EDITION

Stacy Palen, Laura Kay, Brad Smith, and George Blumenthal