AST 2002Introduction to Astronomy

• Textbook– The Essential Cosmic Perspective, by

Bennett. – Included with your textbook should be an

access package for MasteringAstronomy

AST2002

• Your Professor– Dr. Dan Britt

– Office is PSB 442

– Office hours are • T Th 9:30-10:20 AM

Grading • 3 exams (80% of grade)

– The first two exams will cover 1/3 of the course each– The final is will be comprehensive with extra emphsis on the last

1/3 of the course.

• Quizzes (10%)– I will give brief in-class quizzes on the book material every week. – It will cover the material to be discussed. Read the book in

advance!

• Readings (10%)– There are 12 short articles assigned. – We will discuss each in class and you will be graded on your

participation.

• Scores will be posted on MyUCF Grades.

Lectures• I am not here to read you the book

– I am what is called an “expert”– There are lots of important things that I think you

NEED TO KNOW are NOT in the book….they will be in the lectures

• I will post the powerpoints I use – http://physics.ucf.edu/~britt/AST2002/– BUT….This is NOT an on-line class– Almost every class will have a section that is NOT in

the Book and will NOT be put in the on-line powerpoints….but will be on the tests.

– There is no substitute for coming to class

Extra Credit• Attend an observing session at the Robinson

Observatory AND write up an Observing Report of what you have seen: 2% extra – Observing report forms will be available at the Observatory– YOU MUST turn in your observing report at the

Observatory, NO forms will be accepted in class.

• This extra 2% usually moves someone a grade higher

• Observatory schedule is posted– http://planets.ucf.edu/observatory/openhouse– Extra credit must be completed before April 15, so go early!

Robinson Observatory

• Watch the posted schedule for dates• Time: Is listed OR when it gets

dark……!• Clouds? IF it is cloudy….Robinson will

be closed.• Standing in the rain at Robinson does

NOT constitute extra credit.

Robinson Observatory

How to Get an “A”• Attend class!

– People who blow off the lectures don’t do very well….figure 30% of test questions will NOT be from the book or posted slides

• Participate in Class– 10% of your grade will be participation and

discussion– I will give extra points for good questions and

discussion.

• Read the book! – Quizzes will be in advance of the lectures

• DO the extra credit!

Dr. Britt’s quirks• This is a small class….discussion will

be key!• I ask questions…..

– Correct answers get points.• I invite you to ask questions.

– You do get points for good questions….• One more thing……

– I am on various NASA review and advisory panels, so I will be gone sometimes.

– I also have to attend scientific meetings.– You will have guest lecturers.

Lets do a little front-porch science…

What can you tell about the history and composition of the Moon just from what you can see from your

front-porch?

What do you see?

What do you see?

Dark StuffLight Stuff

Light Stuff

What can you tell me about the Light Stuff?

Light Stuff

What can you tell me about the Light Stuff?

• It’s lighter

• It has more craters

• It covers more of the surface

Dark Stuff

What can you tell me about the Dark Stuff?

Dark Stuff

What can you tell me about the Dark Stuff?

• It’s darker

• It has fewer craters

• It covers less of the surface

What does having more craters mean?

So the light stuff is older…. How did the dark stuff get

where it is?

Let’s recap what we know

• The Moon has Dark Stuff and Light Stuff

• The Light Stuff is…. – Lighter, has more craters, and is older

• The Dark Stuff is….– Darker, has fewer craters, and is

younger

• What does this mean for the history of the Moon?

So….what can we KNOW about the Moon from a few simple

observations?

• It has two major regions• Those regions were created at MUCH

different times• The older Light Stuff was subjected to

EXTREMELY heavy cratering• The younger Dark Stuff appears to have

flowed over the low-lying Light Stuff– The Dark Stuff was once molten and probably

like terrestrial basalt (lava).

Not bad for an evening spent on the porch….

• A few simple observations can tell you a great deal about an object.

• To know more took sending humans to the Moon.

So…..where would you send Humans on the Moon?

But, the engineers have a few constraints:1. Can’t land north or south of these lines2. Can’t land on anything rough

11

1517

161412

Apollo Landing Sites

Astronomy is…..

• In this class Astronomy means a whole lot more than looking through telescopes.

• Astronomy is really about how the Universe is put together

– How it was created

– How it evolves

– Why there are planets

– How Earth fits in the scheme of things

Where do we come from?• The first (and simplest) atoms were created

during the Big Bang.• More complex atoms were created in stars.• When the star dies, they are expelled into

space…. to form new stars and planets!

Most of the atoms in our bodies were created in the core of a star!

Looking back in time• Light, although fast, travels at a finite speed.• It takes:

– 8 minutes to reach us from the Sun– 8 years to reach us from Sirius (8 light-years away)– 1,500 years to reach us from the Orion Nebula

• The farther out we look into the Universe, the farther back in time we see!

A Sense of Scale

• The first difficult concept is the immensity of time and space

• What we will be doing a lot of is stepping out of human scale

• Astronomers talk about large numbers in powers of ten…..

– This is just a shorthand for writing large numbers

– For example the distance to the Sun is 150 million Kilometers (150,000,000 Km) or 1.5 x 108 Km

• The planets outside the Air and Space Museum in DC (1:10 billion)

• Our Sun is the size of a grapefruit, Jupiter the size of a marble

• At this scale the nearest star would be another grapefruit in San Francisco

100 (1 meter)

101 (10 meters)

102 (100 meters)

103 (1000 meters)

104 (10,000 meters)

105 (100,000 meters)

106 (1,000,000 meters)

108 (100,000,000 meters)

1010 (10,000,000,000 meters)

1012 (1,000,000,000,000 meters)

1013 (10,000,000,000,000 meters)

1020 (100,000,000,000,000,000,000 meters)

1022 (10,000,000,000,000,000,000,000 meters)

1026 (100,000,000,000,000,000,000,000,000 meters)

Aldebaran translates as "the follower", because this star appears to follow the Pleiades

How big is the Universe?• The Milky Way is one of about 100 billion galaxies.

• 1011 stars/galaxy x 1011 galaxies = 1022 stars

As many stars as grains of (dry) sand on all Earth’s beaches…