Download Astronomy Quiz Units 1 to 3

Astronomy Quiz Units 1 to 3a
Name_________________________________
1. What is the radius of the Earth in kilometers?
REarth = 6,378 km (Just look it up.)
2. The Moon has a radius of 1,738 km. Demonstrate that the Moon is just over ¼
the size of the Earth.
Look up the radius of the Moon in the text appendix and then use a ratio
RMoon 1,738km
1

 0.272  27% 
REarth 6.378km
4
3. The object shown in the picture to the right orbits the Sun at a
distance of 1.458 AU from the Sun but is not considered a
planet. Why not? Answer in a sentence.
The answer as to why this object is not a planet is that it is
not spherical.
“A planet (from Greek πλανήτης, alternative form of πλάνης "wanderer") is a
celestial body orbiting a star or stellar remnant that is massive enough to be
rounded by its own gravity, is not massive enough to cause thermonuclear fusion,
and has cleared its neighboring region of planetesimals. “ (Wikipedia)
I did not count this problem because I erroneously thought that it was covered in
Unit 1. I was mistaken.
4. Circle the objects below that are part of our Solar System
a. The Milky Way
d. Pluto
b. Jupiter
e. Comets
c. M31 (Andromeda
f. Polaris (The North Star)
Galaxy)
5. If Jupiter is 5.2 AU from the Sun, how many kilometers is it from the Sun?

5.2 AU  5.2  1.5 108 km
  7.8 10 km
8
AU
There are 780 million kilometers in 5.2 AU
6. Imagine the whole universe was scaled down so that the Earth were the radius of
a tennis ball (radius = 3.5 cm).
a. Use a proportion to determine how many centimeters away would the
nearest star be if the nearest star is actually 4.3 ly away?
RTennisBall
x

REarth
DNearestStar
x
RTennisBall
 DNearestStar
REarth
x
3.5cm 
  4.3ly  9.46  1012 km 
ly 
6,378km 
x  2.23  1010 cm
If the Earth were the size of a tennis ball, there would be 2.23 x 1010cm
(22.3 billion cm) between Earth and the nearest star.
b. How many kilometers would that distance be?
2.23 x 1010 cm (22.3 billion cm) is equivalent to 2.23 x 108 m and 2.23 x
105 km.
7. Describe the celestial sphere in a few sentences.
Full credit for
 A conceptual model of the Sky
 Carries the stars
 Appears to rotate westward once every 23h 56m 4.09s
 NCP, SCP and Celestial Equator are aligned with the Earth’s north
pole, south pole and equator respectively.
 Is divided into regions using Right Ascension and Declination.
8. What are special about the apparent motion of the celestial poles on the celestial
sphere?
The celestial poles are the only two points on the celestial sphere that don
not appear tot move on a daily basis.
9. In as sentence define a constellation and state the number of official
constellations.
“In modern astronomy, a constellation is an internationally defined area of the
celestial sphere. In 1922, Henry Norris Russell aided the IAU in dividing the celestial
sphere into 88 official constellations.” Wikipedia
Conversions
Formulas
A
L

2D
360 
Main Sequence Lifetime t 
M
1010 yr
L