Regulus (about 75 light years distant) is part of a 4-star system, with a close companion double star visible to its lower left. Leo I (about 800,000 light years away) is a dwarf galaxy thought to be the most distant of several known small satellite galaxies orbiting our Milky Way Galaxy.

Why are you taking this class? Why does the University consider it important for non-science majors to take a course in the physical sciences?

Science attempts to systemized knowledge through: observing questioning hypothesizing testing Using critical & creative thinking. Scientific thinking has applications to all fields of human endeavors, not just science.

Patterns are discovered. OBSERVING: Patterns are discovered. QUESTIONING: What causes these patterns?

Question everything, including things you “know” Examine your assumptions: Be aware that your thinking is influenced and structured by your previous life experiences, i.e., they are biased. Be creative, but critical, in your thinking!

Our goal is to teach you to be creative, critical thinkers that question authority, not to groom you to take exams!

Let’s begin now …

What happens next?

In some cases we need to revisit things that we “know” Our “knowledge” can be based upon misinformation or errant assumptions consistent with our previous expereinces. Never get too wedded to your own “knowledge”, question it as well.

DISTANCE SCALE

SCIENTIFIC NOTATION Expressing large and small numbers: 10n = 1 followed by n zeros e.g., 3.2 x 109 = 3.2 x 1,000,000,000 = 3,200,000,000 10-n = 1 / 10n e.g., 5 x 10-5 = 5 / 105 = 0.00005

Common prefixes in numbers: Symbol factor tera T 1012 1,000,000,000,000 giga G 109 1,000,000,000 mega M 106 1,000,000 kilo k 103 1,000 hecto h 102 100 1 centi c 10-2 0.01 milli m 10-3 0.001 micro μ 10-6 0.000001 nano n 10-9 0.000000001

Units of Distance in Astronomy Meter: ~ 10% larger than 1 yard Astronomical Unit (AU): Earth – Sun distance, ~ 15 x 106 kilometers ~ 9.3 x 106 miles) Light Year (LY): distance light travels in one year, ~ 9.46 x 1012 km Parsec (pc): ~ 3.26 light years

DISTANCE SCALE Seeing the past

The universe is approximately 14 billion years old Earth is 0.04 light seconds (8000 miles) in diameter Moon is 1.3 light seconds (250,000 miles) from Earth Sun is 8 light minutes (1 AU) distant Next nearest star is 4.3 light years (LY) distant Center of the Milky Way Galaxy is ~ 26,000 LY distant Andromeda galaxy is 2.5 x 106 LY distant We see galaxies greater than 109 LY away

“The Cosmic Connection” A video interlude… “The Cosmic Connection”

Edwin Hubble was the first to observe that, with the exception of very nearby galaxies, all galaxies move away from Milky Way. He also found that the velocity with which galaxies recede from the Milky Way is proportional to distance! The more distant a galaxy is, the faster it is moving away from us. This is a direct prediction of a uniformly expanding universe. BIG BANG – Universe approx. 13.7 x 109 years old

Big Bang (~ 13.7 x 109 yrs ago) T i m e Expansion & Cooling Initially only Hydrogen & Helium Growth of structures (gravity) Stars and Galaxies form Nucleosynthesis - “star stuff” Planets possible - “heavier” elements Solar System forms (4.6 x 109 yrs ago)

Which of the following best describes what we mean by the “universe”? (red) A vast collection of stars that number as many as the grains of sand on all the beaches on Earth. (blue) All the galaxies in all the superclusters. (yellow) The universe is another name for our Milky Way Galaxy (green) The sum total of all matter and energy.

Which of the following best describes what we mean by the “universe”? (red) A vast collection of stars that number as many as the grains of sand on all the beaches on Earth. (blue) All the galaxies in all the superclusters. (orange) The universe is another name for our Milky Way Galaxy (green) The sum total of all matter and energy.

Which of the following has your "cosmic address" in the correct order? You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe

Which of the following has your "cosmic address" in the correct order? You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe

Looking for patterns

questioning: why do these patterns exist? hypothesizing testing observing: look for patterns questioning: why do these patterns exist? hypothesizing testing