1. Astronomy 104 If you are not registered for the class:
The class is full, and the instructor cannot add more students!
(lab space is limited)
A tiny chance to get in:
• if you attend the first two classes
• and you are lucky enough to take a seat of someone who drops
Note this:
• you must take the slot as soon as it opens
(through on-line registration)
• there is no guarantee you get lucky
THERE IS NO WAITING LIST FOR THIS CLASS.

2. Prepare your scantron:
Use
a pencil,
not a pen!
Fill in your name and fill the bubbles under
your name.
LAST NAME FIRST, First name second
Put your 4-digit code instead of “IDENTIFICATION NUMBER”.
--- (The last 4 digits of your OleMiss ID.)
Question # 1: answer A
Question # 2: answer A
Question # 3: answer A
Setup:
Note extra credit deadlines:
Signup: Sept > contact Shadi
Image Proc. Lab turned in: Sept. 17
Reading assignment:
Chapter 1, pp. 1 – 24
Labs next Monday or Tuesday – buy the lab book!
Please take a moment to mute your cell phone!

3. The hierarchy of the Universe, Step 1
Step 1: Earth and the Moon
Memorize this, please!
Size : 12,756 km = 7972 miles
Size: 3476 km
Earth
Moon
Distance: 384,400 km

4. The hierarchy of the Universe, Step 2
Step 2: the Solar System
The hierarchy of the Universe, Step 2
Planets
The
Sun
is a
STAR
The planets revolve around the Sun
and reflect sunlight
(they are not in a bunch as in this picture)
Distance = 150 million km
= 1 AU
Earth
(Astronomical Unit)
Memorize this, please!
Distance = 400,000 km

5. The hierarchy of the Universe, Step 3
Step 3: Stars
Each star may come with its own planets
(we cannot see these planets directly: too small and far away)
Star
Star
Sun
Star
Distance = a few light years
1 light year = 10,000 billion km (= 1013 km)
Star
The hierarchy of the Universe, Step 3
Star
The closest star (except the Sun): Proxima Centauri light years

6. The hierarchy of the Universe, Step 4
~ 100,000 light years
Consists of
100 billion
stars and a
little rare gas
between
the stars.
Where this gas
is a little less rare,
it glows
and is called
a nebula:
The
Milky
Way
is a
galaxy:
the
Galaxy
Sun
The hierarchy of the Universe, Step 4
Step 4: the Milky Way

7. The hierarchy of the Universe, Step 5
Step 5: The whole Universe
The hierarchy of the Universe, Step 5
Consists of
1000 billion
galaxies.
Size:
10 billion light years
The
Milky Way
Distance = 400,000 km

8. Questions coming …

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Question 4
Which one of the following is large enough contain a nebula?
A a star
B a solar system
C a galaxy
D a planet
E none of these
Next question coming …

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Question 5
Which of the following is wrong?
A The Universe consists of galaxies.
B Galaxies consist of stars.
C Solar systems consist of one star and planets.
D Planets get their light from their stars.
E All the above is correct.
Next question coming …

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Question 6
Where is the Sun located in the Universe?
A In space, far away from all galaxies.
B In the center of the Galaxy.
C In a nondescript location in the Galaxy.
D In the middle of a spiral arm of the Galaxy.
E In the center of the Universe.
Next question coming …

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Question 7
What is a light year?
A A time as long as the lifetime of a star.
B A long time. Stars live a lot longer than one light year.
C A distance comparable to the distance between
closeby stars.
D A large distance. Closeby stars are usually much
closer to each other than one light year.
E A large distance, comparable to the size of the
whole Universe.