Introduction to Astronomy &
Tools of Science
(Chapter 1)
Student Learning Objectives
• Diagram your location in space
• Write and interpret numbers in scientific notation
• Define astronomical distance measurements
• Apply the scientific method.
What is our location in space?
 We live on planet Earth
 In the Milky Way Galaxy
(1012 stars)
 Part of the Local Group
(Galaxy Cluster)
 Within in the Virgo
Supercluster
 One tiny spot in the
visible Universe
Practice
Diagram your location in space.
What is Scientific Notation?
Multiples of 10
 The number of multiples/divisions of 10 is
indicated as a power.
Blue Light
Earth-Sun
l = 450 x 10-9 meters
d = 93 x 106 miles
Practice
1) Write 67,000 in scientific notation - Distance
from center of galaxy to Sun
2) Write 1012 in standard notation - Number of stars
in our galaxy
3) Write 3.5 x 10−14 in standard notation - A
frequency of red light
What is the measurement system used in astronomy?
metric system
 Each factor of ten difference results in a single move of
the decimal.
Prefix
Mega
Kilo
Micro
Nano
Angstrom
Power of Ten
106
103
10-6
10-9
10-10
Word
Million
Thousand
One Millionth
One Billionth
Practice
1) Red light has an average wavelength of 650 nm. Is
this a very small or very large number?
2) Distances to galaxies are measured in Mega-parsecs.
This is (hundreds, thousands, millions) of parsecs.
(choose one)
How are astronomical distances measured?
Distances between objects in space are huge!
The astronomical unit (AU) is the average EarthSun distance.
1 AU 1.96 x 108 km 9.298 x 107 miles
Light Year
A light year measures distance, not time.
The light-year (LY) is the distance light travels
through a vacuum in 1 year.
Light travels 1 AU in about 8 Minutes
Earth - Moon: 1.3 Light Seconds
Earth - Sun: 8 Light Minutes
Earth - Mars: 13 Light Minutes
Earth to Proxima Centauri (nearest star)
4.3 Light Years
Earth to the other side of our own galaxy
52,000 Light Years
The parsec (pc) is the distance at which 1 AU
subtends 1 arcsecond.
1 pc
3.26 LY
206,265 AU
1º = 3600´´
Practice
What is the correct order from smallest to largest?
1 mile
1 pc
1 LY
1 meter
1 nm
Earth’s Diameter
1 AU
What is science?
 Science is not simply a
collection of facts, but
rather an objective
process of quantifying
what we observe.
 The outcomes of science
are laws and theories
with repeatable results.
Tested
Verified
How is science done?
• Measurements
• Observations
 Each scientist must be able to obtain the same results.
Observe/Question  Hypothesize/Predict
 Observe/Confirm  Theory 
Example: Atomic Spectra
Questions to Consider
1) The scientific method is a circular process. Explain
2) What do you think happens if scientists cannot obtain
the same results?
3) Can the scientific method be used to answer all
questions?
4) What is pseudoscience?
What is astronomy?
Astronomy is a science.
Astronomers study the universe and all objects
contained within the universe.