A100 Solar

System

Today’s APOD

Read Preview in text – “Cosmic Landscape” Quiz Monday (essential facts and scientific

notation) Rooftop Session Sept. 10, 9 PM 1st Homework due Sept. 12 (get it on

Oncourse)The Sun Today

Wednesday, Sept. 5

The Sun Today

SolarOrbiting

Heliospheric Observatory

(SOHO)Orbits between the Sun and Earth, about a million miles

away – a constant view of the Sun

No sunspots – the Sunis in a phase of low

activity

Spectacular Solar Prominence on Sunday, Aug.

31

Photo by Mike Borman, Evansville

Write and work with very large or small numbers without so many digits.

Only one digit should be in front of the decimal.

The exponent positive when the number is greater than one, negative when the number is less than one.

Review Scientific Notation

43,000,000. = 4.3 x 107

0.000043 = 4.3 x 10-5

Use the worksheet with the syllabus for practice

Powers of 10Power of 10 Notation Prefix Abbr.

billion 109 “giga” G

million 106 “mega” M

thousand 103 “kilo” k

hundredth 10-2 “centi” c

thousandth 10-3 “milli” m

millionth 10-6 “micro” billionth 10-9 “nano” n

Basic DefinitionsDistances Solar Radius (700,000 km)Astronomical Unit (AU)Light year

MassEarth massesSolar masses

SpeedSpeed of light(300,000 km per second)

Use approximate numbers

Using those essential facts! Which of the following diagrams most

closely depicts the relative sizes and distance between Earth and the Moon?

How do Astronomers Know?

Create a CONCEPT MAP Start with concepts (words we have for ideas) Form concepts into a hierarchical organization

lower levels that are more specific and less general than the higher levels

Add examples (illustrative nouns or names of specific people, events, places, or objects, at the lowest level of the hierarchy)

Add linking words or phrases (describe how one concept relates to another)

Add cross-links (show the relationship between one branch and another)

Hints: Concepts appear only once

Are all links and concepts relevant? Are examples relevant, appropriate, and representative?

About Learning Astronomy1. Pay attention to the diagrams

– What is shown in the diagram?– What basic concept is illustrated?– Why is the diagram included in

the text or lecture?

More complex diagrams may contain a lot of information

How do these two diagrams relate?

Looking at Scale

What information is shown in these two diagrams of the local bubble?

What is the relationship between them?

About Learning AstronomyUse physical models

Physical models can help you visualize the relationships among bodies in the Solar System

Modern science relies on observations and

experiments!

Understanding Science

Purpose – to understand the universe well enough to figure out the basic relationships that govern it

A process for understanding and predictingwill it rain tomorrow?what will be on the quiz?what will happen if…?

What about facts?new discoveriesbetter datanew theoriesfacts change!

The Science

of Astronomy

Learn what is known

and what is NOT known…

Develop a model to explain or describe what is knownUse the model to predict what is not known

TEST the predictions

Refine the model

But science rarely proceeds in this idealized way… For example: • Sometimes we start by “just looking”

then coming up with possible explanations.

• Sometimes we follow our intuition rather than a particular line of evidence.

Testing the PredictionsExperiments and Observations

repeatablequantitative well definedfair

Statistics evaluate the reliability of observations

Examples What time is it? Heads or tails?

Laws and Theories (and models)

A law is a set of hypotheses that explains WHAT is happening – usually mathematicalKepler’s laws of planetary motion

A theory is a well-developed set of hypotheses that explains why many related natural phenomena happenEinstein’s Theory of General Relativity

Laws and theories are both based on detailed and repeatable observations and measurements

Laws and theories both yield testable predictions

What is a scientific theory?

• The word theory has a different meaning in science than in everyday life.

• In science, a theory is NOT the same as a hypothesis, rather:

• A scientific theory must:—Explain a wide variety of observations with a few

simple principles, AND—Must be supported by a large, compelling body

of evidence.—Must NOT have failed any crucial test of its

validity.

Is a Theory Right? Can’t ever “prove” a theory rightDoes the theory make correct

predictions?If it doesn’t, then it’s wrong

If it’s not tested or testable, it’s NOT a scientific theory

Burden of proof is on the person making the claim“Extraordinary claims require

extraordinary proof” (Sagan)

An Ongoing Process

The process of science has been so successful becauseresults are widely shared and

evaluatedexperiments are reproduced and

checkedvalue of ideas based on observation

and usefulness, not authority

Criteria of ScienceConsistent: The results of repeated observations or experiment are more or less the same.

Observable: The event under study can be observed or natural evidence must be available.

Natural: A natural caused must be used to explain why or how the event happens

Predictable: The natural cause can be used to make specific predictions.

Testable: Predictions must be testable through observations or experiments.

Tentative: Science is subject to revision and correction based on new observations

• Consistent • Observable • Natural • Predictable • Testable • Tentative

Debating Scientific IssuesHow do we tell who is correct?

Majority vs. minority opinionsMajority isn’t always right Debate is a poor technique for deciding

EVIDENCE and DATAHow was the experiment done?Was it repeated by others

Is a new theory TESTABLE?

How can we distinguish

science from non-science?

• Defining science can be surprisingly difficult

• Science from the Latin scientia, meaning

“knowledge”

• But not all knowledge comes from science…

Warning Signs of Bad ScienceHow is it announced? Is the source reliable?

How good is the evidence?is it anecdotal? does it appeal to authority?does it fit what you already know?does it violate widely-accepted laws or theories?is contrary evidence ignored?

What kind of reasoning is used?Can the claim be tested?

The Baloney Detection Collection

Phil Plait's Bad Astronomy: Home Page

PLANET-DISSOLVING DUST CLOUD IS HEADED TOWARD EARTH!

September 12, 2005, by Yahoo! News

• By MIKE FOSTER

CAMBRIDGE, Mass. -- Scared-stiff astronomers have detected a mysterious mass they've dubbed a "chaos cloud" that dissolves everything in its path, including comets, asteroids, planets and entire stars -- and it's headed directly toward Earth!

Discovered April 6 by NASA's Chandra X-ray Observatory, the swirling, 10 million-mile- wide cosmic dust cloud has been likened to an "acid nebula" and is hurtling toward us at close to the speed of light -- making its estimated time of arrival 9:15 a.m. EDT on June 1, 2014. The bad news is that the total annihilation of our solar system is imminent.

To avoid widespread panic, NASA has declined to make the alarming discovery public. But Dr. Sherwinski's contacts at the agency's Chandra X-ray Observatory leaked to him striking images of the newly discovered chaos cloud obliterating a large asteroid.

“If it continues unchecked, the chaos cloud will eventually reduce our galaxy to the state of absolute chaos that existed before the birth of the universe,” the astrophysicist warned.

One question I’ve always had about astronomy is…

ASSIGNMENTSthis week

Read “Cosmic Landscape” Quiz on essential facts and

scientific notation on Monday

Rooftop Sky Viewing Sept. 10

1st HW due Sept. 12

Dates to Remember