Astronomy 1020-HSpring_2015

Day-4Stellar Astronomy

3X5 card question• Name (legible!legible!):

• What scientist (living or not) would you most like to meet?

Course Announcements• Smartworks Chapter 1: Start on –

Grades will be downloaded sometime after Friday.

• SW-2 … hop to it.

A Scientific Result: We Are Stardust

Our bodies contain many types of atoms.Except for the hydrogen in water (H2O), all

the atoms were made in stars.Stars generate energy by making heavier

elements out of light ones.They eject the material into space.New stars and planets (and humans) form out

of the ejected material.

Science Is CreativeScience is one of many creative human

activities.It has its own rules for deciding what is right

and wrong.It is an important way for achieving

knowledge and insight.There are also other valuable ways to

achieve understanding.

Science Is a Process• Science is a method for learning about

nature.• The scientific method works like this:

• Ideas are tested against nature.• Tests come from observation or calculation.• The tests falsify some ideas and support

others.

• All scientific knowledge is provisional.• Science involves Exploration & Discovery

• HST• Curiosity

Scientific Method• To be accepted as

valid, an idea must be testable and falsifiable.

• This separates “fact” from “faith”.

• We use the “Scientific Method”

Scientific Revolutions• The scientific processes and investigations

can be slow: many small steps and tweaks.• Every now and then, there is a revolution

and progress is very rapid in both new knowledge gain and understanding the implications and effects.• Newtonian Mechanics• Quantum Mechanics• Evolution

Challenges to Science• Science is subversive.• Old ideas can be falsified and rejected.• New ideas must be supported by evidence.• Authority often works by suppressing

inquiry.• Scientific authority can be overthrown by

new or better evidence.• Nature is the arbiter of science. It decides

what ideas are good or bad. (Occam’s Razor)

New Concept:Cold Dark Matter

A Strange Universe

Cute and Science

Colored Card QuestionThink-Pair-Share

The Milky Way is:

A) A nutty candy bar B) A spiral galaxy C) An elliptical galaxy D) Haven’t got a clue.

An Important AssumptionThe cosmological principle: “There is

nothing special about our place in the universe.”

On one level:Our view from the Earth is not special or

unique.Distant objects should be like nearby ones

which we can study in detail.On another level:

Matter and energy obey the same physical laws everywhere.

Math• Review page 16 – Math Tools 1.1 box.• You should feel comfortable working at this

level.• You’ll need at least these skills just to live in

the modern world.• Scientific Notation• Ratios• Geometry• Algebra• Proportionality

Scientific Notation4,500,000,000,000,000 = 4.5x1015

0.000000000000000028 = 2.8x10-17

On calculators…look for the “EXP” keyor the “EE” key

centi = 0.01 = 10-2 (c)

milli = 0.001 = 10-3 (m)

micro = 0.000001 = 10-6 ()

nano = 0.000000001 = 10-9 (n)

kilo = 1,000 = 103 (k)

mega = 1,000,000 = 106 (M)

giga = 1,000,000,000 = 109 (G)

tera = 1,000,000,000,000 = 1012 (T)