Solutions to all Prather et al. workbook pages relevant
to what we covered in Chapter 1.


For section 1 of Chapter 1:
"Looking at Distant Objects" - pp 131-132

For section 2 of Chapter 1:
"Sun Size" - pp 105-108
"Milky Way Scales" - pp 123-126



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Looking at Distant Objects:

#1: Light-year is a unit of distance, the distance
light travels in one year.

#2: Sydney lives 4.3 ly from the Sun.

#3: 11.4 years -- Crystal's picture takes that long.

#5: Yes, the farther away the child lives, the older he/she
is when you actually receive his/her message.

#6: Crystal sent her picture first and Sydney sent her picture last.

#7: As it wasy 2.5 million years in the past. Light takes
that long to travel the distance between Andromeda Galaxy and here.

#8: 10 million years, 40 million years, 60 million years ago.

#9: a and e






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Sun Size:

1. baseball

2. you should draw something that has the Moon 
30-earth diameters away from Earth. 

3. d.

4. five things that might work:
basketball and grain of sand
basketball and pea
soccerball and grain of sand
soccerball and pea
baseball and grain of sand

5. two Moon orbits would fit across the Sun.

6. d.

7. no -- a basketball Sun would need a pea
or grain of sand for Earth.

8. about 440. If 110 Earths fit across Sun,
and 4 Moons fit across Earth.....

9. about 220. If 110 Suns fit in the distance
between Earth and Sun, and 2 Moon orbits fit
across the Sun....



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Milky Way Scales


1. about 30000 ly.

2.  AAAAA. Since 1000 light years is just 1 millimeter,
all these stars are about 1 millimeter or less from the Sun.
That can only be dot A.

3.  No Deneb is not distant, a large fraction of the Milky Way
is farther away from the Sun than Deneb is.

4. Inside -- the Milky Way is much bigger than even
Deneb's distance.

5. ABC. M45 is less than 1 mm away. M1 is just about 6 mm away.
M71 is about 13 mm (1.3 cm, about half an inch) away.

6. They are part of it. Though the distances are generally
bigger here than problem 3, they are still smaller than
the Milky Way's overall diameter.

7.  Tiny dot. If 1000 light years is 1 millimeter, than 11
light years is much much smaller than a millimeter. So 
no blob of any size that you could conceivably draw would
be small enough. Has to be a dot.

8.  The dot is way too big.

9.  A dot for SagDEG fits, a dot for LMC might fit, and a dot
for M31 does not fit. SagDeg is 80 mm ( = 8 cm = about 3 inches)
away. LMC is 160 mm ( = 16 cm = about 6 inches) away. M31
is 2500 mm ( = 250 cm = 2.5 meters = about 8 feet) away.

11. SagDEG actually could use a blob. 11000 light years
is about 11 millimeters.

12. Virgo cluster would be 60000 millimeters away = 6000 centimeters
= 60 meters = about 200 feet.