Welcome to Astronomy
101 – Under the Dome
Sec 5 – Intro to the Course and the
Scientific Method
Should I Be Here?
• If you are a science, math or
engineering major and have
already taken Math 150, Phys
151 or equivalents, you should
consider taking Ast 270
• THE OFFICE OF ACCESSIBILITY RESOURCE
CENTER IS LOOKING FOR A STUDENT IN THIS
CLASS TO VOLUNTEER TO PROVIDE NOTES
FOR THIS CLASS. THE STUDENT WILL BE PAID
A STIPEND FOR THE SEMESTER. INTERESTED
STUDENT SHOULD COME BY OUR OFFICE AT
2021 MESA VISTA HALL TO COMPLETE THE
REQUIRED HIRING PAPERWORK.
Course Intro
• Instructor: Dave Pitonzo, PhD
• dgpitonzo@salud.unm.edu
• Office hours: 30 min before or after class on
Tu/Th or by appt.
• Fri. evening observing on Main Campus at the
“domes” on Yale – very helpful if you are also
taking the lab!
Roger A. Freedman • Robert M. Gellar • William J. Kaufmann III
•
Required
course text
• Weekly
reading from
this book
• Eversion
available free
on publisher’s
website with
Required course text helpful review
questions and
Other required readings will be announced in theactivities
future
to supplement topics in the text
• 4 exams – MCQ, short answer, essay
• You will be permitted 1 page (2-sided) of handwritten
notes for each exam. No books or other references
BUT
• lowest grade will be dropped
do NOT miss any
exams unless there is an emergency! That is the
reason for this policy because there are no make-ups
for missed exams! (if you miss two exams for very valid
reasons you will need to set up an appt. within one
week.
• Here is the good part…
Grading (cont)
• If you do really well on the first three exams,
you may elect not to take the last one!
• You must, however, continue to attend lecture
because attendance is required!
• Attendance and participation will
be worth 10% of your grade!!!
• I have found that students usually prefer this
to graded homework assignments,
presentations and papers.
Grading (cont)
• SO:
• Three out of four exams each worth 30%
• Attendance and participation 10%
• Every two missed classes is automatic 1%
deduction
• So please do NOT take this section if you
have other commitments that will interfere
with attendance
Material/WebPage
• 75% of testable material will come from
lecture material
• 25% from readings – weekly readings for each
class are listed on the syllabus (webpage).
Check the schedule regularly for changes!
Check webpage for weekly course objectives
• Check webpage for weekly homework – these
are for your help in studying – they are not
handed in for credit
SO…
Why are you here?
•
•
•
•
•
Keep off streets?
Why are you here?
Air conditioning?
No parties on Mon/Wed nights?
Easy “A” ?(heh, heh!)
Fill core curriculum requirements instead of
taking biology, chemistry, physics?
OK, since you brought it up, how
about the math?
• AST 101 is designed as a survey course, not an
instrument of torture
• BUT (here it comes)
• You need to understand the math in order to
understand HOW we know what we know.
• YOU should have a basic understanding of
high school math: algebra, basic trigonometric
functions, exponents, logarithms, metric
system
The
math…
• You will NOT be asked to make difficult
calculations but you may be asked qualitative
questions about math as related to questions
in astronomy
110,000 ly
300,000 AU
2,300,000 ly distant
Distance to center of Virgo cluster – 70,000,000 ly
100,000,000,000 ly
Enter the megaparsec –
more about that later
Now, back on topic: Why are you here?
Why is astronomy interesting?
• It is a scientific discipline that is well suited to
ask (and hopefully begin to answer) some of
the deepest questions.
• Where did the universe come from?
• Where is it going?
• How likely is life elsewhere in the universe?
• What is the significance of humanity?
• Are there alternate realities?
The questions….
• As we go
through the
course, we
will try to
illustrate why
a given topic
might be
relevant to
answering
these
questions!
Why is astronomy especially suited to
this purpose?
NGC 891
in Andromeda
Photo by Hubble
Summer Milky Way
photo by Jerry Lodriguss
NGC 1365 in
Fornax
M83 in Hydra
How does astronomy help us find out about the
universe?
• Astronomy is a
science
• Science is a
philosophy
• What is its main
tenet??
• Anyone, anyone?
The bedrock of science
• THAT WE CAN UNDERSTAND THE UNIVERSE BY
• This may sound trite but it was not always this
way.
• there are certain rules for observing.
– The observations must be quantifiable (hence the
whole math thing), reproducible (by who?), controlled
(so we can make sure the effect is real) and validated
(confirmed by another method)
Accuracy and
• Accuracy: how close to the right answer
• Precision: the reliability of measurement. Essentially a
measure of random error.
• a study can be very precise but inaccurate.
What would imprecise but accurate
look like??
What would imprecise but accurate
look like??
Related to the concept of precision is reliability. This is defined
as the consistency with which results can be reproduced. It
generally applies to larger scale phenomena. Individual trials
can be precise or imprecise. Whole studies are reliable
(reproducible) or unreliable. Validity is to accuracy as
reliability is to precision
The Hypothesis
• Scientists ask questions in the form of hypotheses –
e.g. Einstein’s general relativity – Does the sun warp
the space around it?
• Experiments are then designed to test the hypothesis.
Let’s look at stars “near” the sun during a total eclipse
and measure any change in position.
Paradigm
• models or frameworks that are derived from
an experimental understanding of nature.
Paradigms are shared by a scientific
community and guide how a community of
researchers act with regard to inquiry.
• eg Newton vs Einstein
Models
• Once the parameters for “observation (i.e.experiment) are met…
• …we create a model, or a potential mechanism explaining the
observations consistent with previously established and the laws of
physics, chemistry, etc.
• e.g. the Ptolmaic model of a geocentric solar system
• Is this model consistent with observations??....
Ptolemy
• Nature of planets and orbits was
• a few learned people even in ancient times actually
believed that the earth and planets orbited the sun,
NOT the earth and believed the earth was round
• What was the primary reason for the Ptolmaic model??
– different epistemology (worldview)
– Low quality observations
• THEY WEREN’T SCIENTISTS, SO THEY CONVENIENTLY
IGNORED CERTAIN THINGS AND BELIEVED IN IDEAS
THAT WEREN’T VERIFIED BY OBSERVATION!
• Like what??
The orbit of Venus
• If Venus and the sun both went around the
earth, then, at times, Venus (and Mercury)
would be seen opposite the sun in the sky
when in fact it NEVER IS!!! So…
Deferents, epicycles, epiepicycles,
equants
• They created an “ad
hoc” solution”
• The sun and Mercury
and Venus orbit the
earth at the same
speed
• But if this were the
case, we would never
see Venus illuminated
Were they idiots?
• No, but most people never bothered to make the
detailed observations, some obsevations were
impossible to make at the time, and…
• The idea of the earth at the center was, on the
“face” of it, both appealing and “logical” – face
validity (we call it common sense)
• After all the earth did not feel like it was moving,
things weren’t flying around, so how could it be
moving.
• It took a long time for the explanation
The next step.
• The theory
• A model that has withstood
many observational tests,
been validated by multiple
methods and is now used as
the BASIS for future
experimentation.
• e.g. we used the Newtonian theory of gravity to calculate the
trajectories for all the robotic spacecraft that have been sent
throughout the solar system
• It all worked perfectly.
• Now it’s the LAW!
M63