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Astronomy 1001
Stars and Galaxies
(Introductory Astronomy Part 2)
An introduction to astronomy beyond the
solar system for non-science students. Topics
include: the Sun as a star, stars and star
clusters, stellar evolution, nebulae, the Milky
Way, galaxies and galaxy clusters, active
galaxies, cosmology.
Homework consists of bi-weekly assignments
and labs, some of which require the use of the
Burke-Gaffney Observatory.
Lecture 1. Key Points
1. Layout of the course.
2. Astronomy as a science.
3. Examples of astronomy in everyday life.
4. The scale of the universe.
Distance = Time.
5. Science versus pseudoscience. Is the
concept testable?
6. Getting started. Learn your way around
the night sky.
http://www.ap.smu.ca/~turner/A1001.html
1. Layout
Course textbook:
21st Century Astronomy
Hester, Smith, Blumenthal, Kay, Voss
Read… read… read… read… read…
Assignments/Lab Exercises (biweekly)
25%
Mid-term Test (February)
25%
Final Examination (April)
50%
Observing Projects*
20%
Total Grade
100%
* Can replace portion of grade from any other
component of final grade.
2. Astronomy as a Science
Science versus pseudoscience: is the concept
testable: falsifiable? E.g. astrology, Van Daniken,
Velikovsky…
Much of what is depicted in the Star Trek and
Star Wars shows is actually unrealistic and
contradicts basic laws of physics, but so is a lot of
what is displayed in most action movies.
3. Examples of Astronomy in Everyday Life
Van Gogh’s Starry Night Over Rhone 1888
The beginnings…
Perfect Numbers
?
The beginnings…
Perfect Numbers
?
A perfect number is the sum of
its proper positive divisors, e.g.
6=1+2+3=123
28 = 1 + 2 + 4 + 7 + 14
= 1  2  14
=147
Very few perfect numbers exist.
6, 28, 496, 8128, 33,550,336,
8,589,869,056
28 is close to the length
in days of the Moon’s
phases (29½ days).
6 is the basis for many
different numbers we use
every day: 24 hour day, 6sided die, 360° circle, etc.
Ordering the Planets Outwards
Object
Motion relative to the Stars
Stars
Saturn
Jupiter
Mars
Sun
Venus
Mercury
Moon
infinite
29.30 years
11.86 years
1.88 years
365¼ days
225 days
88 days
27½ days
Saturn governs the 1st hour of the 1st day, Jupiter
the 2nd hour, Mars the 3rd hour, etc., and Mars the
24th hour. The Sun then governs the 1st hour of
the 2nd day, the Moon the 1st hour of the 3rd day,
Mars the 1st hour of the 4th day, Mercury the 1st
hour of the 5th day, Jupiter the 1st hour of the 6th
day, and Venus the 1st hour of the 7th day. The
days of the week are therefore:
Saturn-day
Sun-day
Moon-day
Mars-day
Mercury-day
Jupiter-day
Venus-day
What examples can you think of?
4. The Scale of the Universe
The speed of light in a vacuum is a constant speed
of ~300,000 km/s. The speed of light is the
maximum speed that anything can travel. The
distance that light travels in one year is referred
to as a light year, and it is a measure of distance
not time.
Earth – Moon = 1¼ light second
Earth – Sun = 8½ light minutes
Earth – Neptune = 8¼ light hours
Earth – Proxima Centauri = 4 light years
Earth – Milky Way Centre = 26½ thousand l.y.
Earth – Andromeda Galaxy = 2½ million l.y.
Earth – UGC 3378 (SN 2010LT) = 250 million l.y.
10 billion years ago, there were no planets.
There are roughly 300 billion stars in the Milky
Way Galaxy.
1 light year = 12 trillion km
Stars are made up of 75% hydrogen, 24% helium
and 1% metals (everything not H or He).
The sun produces helium.
Human beings are composed of elements that are
created in stars.
Astronomy as a science is limited by observations
of celestial objects, and many observations can
only be done once, or, in some cases, not at all.
5. Science versus pseudoscience.
The key: Is the concept testable?
If it is, it is considered a scientific concept. If not,
pseudoscientific.
Examples from the present and past:
astrological forecasts
Van Daniken and visits from UFOs
Velikovsky and bouncing planets
diseases from space?
How many such concepts can you think of?
6. Getting started.
Learn your way around the night sky. An image
from January 5 (morning) by Mike Boschat.
The Summer
Triangle
Groups that
look like their
namesakes.
Hercules
Normally
pictured
holding the
world.
Sagittarius
An archer?
Better pictured
as a teapot.
The Perseus
Group
A story in the
stars.
Ursa Major
Does this group
truly look like a
bear??!
A better way? − from Rambling Through the
Skies, George Lovi, Sky & Telescope, December
1990.
The stars of Orion as pointers.
The field of Orion
The Heavenly G. Captain, all d’uh riggin’ seems
perfectly polished.