Download How Big is the Universe

Objective – After reading an article, I can identify characteristics of the universe.
How Big Is Our Universe?
How many times have you wondered about all the things that we see in the night sky?
The universe contains everything: all the star systems, galaxies, gas, dust, and
everything else.
Stars are huge balls of gas held together by gravity. They are so far away. it would take
more than a lifetime to reach the nearest star to the Sun. Planets are round balls of
rock and/or gas that orbit a star. It can take months or years to reach a planet. Space
probes nine months to travel to Mars. The fastest spacecraft ever launched traveled
36,000 miles per hour. It is the New Horizons spacecraft. New Horizons passed Pluto
in July 2015. It took it 9.5 years to reach Pluto.
Stars and galaxies are so far away, measuring distances is difficult for our minds to
understand. Scientists and astronomers sometimes use a light-year, the distance light
travels in one year, to measure these distances.
Earth is about 93,000,000 miles away from the Sun. It takes light from the Sun 8.3
minutes to reach the Earth. We use the speed of light to measure the time it takes
light to travel over long distances. The speed of light is 186,000 miles per second.
Light-Year Calculation
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60 seconds per minute (x) 60 minutes per hour = 3,600 seconds per hour.
3,600 seconds per hour (x) 24 hours per day = 86,400 seconds per day.
86,400 seconds per day (x) 365 days a year = 31,536,000 seconds per year.
31,536,000 seconds per year (x) 186,000 miles per second = 5,865,696,000,000
miles per year (light-year in miles).
-or 31,536,000 seconds per year (x) 300,000 kilometers per second = 9,469,800,000
kilometers per year (light-years in kilometers).
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Objective – After reading an article, I can identify characteristics of the universe.
The closest star to the Sun is Proxima Centauri. It is near Alpha Centauri.1 Alpha
Centauri is about 4.3 light-years away. It would take about 4 years and 4 months to
reach if you were traveling at the speed of light.
Distance from the Sun in Light Years to the Planets
Planet
Light-Years
Mercury
0.000006 (3.2 light minutes)
Venus
0.000011 (6 light minutes)
Earth
0.000016 (8.3 light minutes)
Mars
0.000024 (12.7 light minutes)
Jupiter
0.000082 (43.3 light minutes)
Saturn
0.000151 (79.5 light minutes)
Uranus
0.000304 (2.7 light hours)
Neptune
0.000476 (4.2 light hours)
Pluto (Dwarf Planet)
0.000625 (5.5 light hours)
Proxima Centauri
4.2
Alpha Centauri
4.3
Most stars belong to a galaxy, a group of hundreds of billions of stars held together
by gravity. Our Solar System is about two-thirds from the center of our galaxy. Our
galaxy is called the Milky Way. The Milky Way Galaxy is made up of about 100 to
400 billion stars.
The Milky Way Galaxy is about 100,000 light-years across. The diameter of our
Solar System is about 0.004 light-years. The Milky Way Galaxy is only one of
billions of galaxies in the universe.
Alpha Centauri is in reality two stars that are slightly smaller that the Sun. They orbit each other
at an average distance that is about the same as the distance between the Sun and Uranus.
1
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Objective – After reading an article, I can identify characteristics of the universe.
p
One of the Milky Way’s neighboring galaxies is the Andromeda galaxy. It is about
2.5 million light-years away.
What’s at the edge of the Universe?
The universe doesn’t have an “edge.” Because space is expanding, the universe is
always getting larger.
The Role of Gravity
Gravity is a force of attraction. Anything with mass has gravity. The strength of the
gravitational force depends on how much mass-the amount of matter in an object-the
objects have and how far apart they are from each other. The greater an object’s mass,
the greater the force of attraction; in addition, the greater the distance between objects,
the smaller the force of attraction.
Human Understanding of the Universe
What did the ancient Greeks recognize as the universe? Their universe had Earth at the
center. The Sun, Moon, and five planets revolved around the Earth. The stars were
attached to a sphere around Earth. This idea held for many centuries. Galileo used his
telescope, an instrument used to view distant objects. He saw there were more stars in
If I have seen further than others, it is by standing upon the shoulders of giants.
-Sir Isaac Newton
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Objective – After reading an article, I can identify characteristics of the universe.
the sky than are visible to the naked eye. Later, astronomers learned they were part of
the Milky Way Galaxy. They also observed many fuzzy, cloudy looking patches. They
were called nebulae. This is the Latin word for clouds. Some of them appeared to be
giant clouds of gas and dust inside the Milky Way. Astronomers debated whether
these nebulae were within the Milky Way or outside.
In the early 20th century, Edwin Hubble saw stars in a nebula in the constellation of
Andromeda. One particular type of star allowed him to calculate its distance. He
showed that the Andromeda Nebula was far outside our Milky Way Galaxy. Hubble
realized that many of the objects that astronomers called nebulae were not actually
clouds of gas. They were what we now call galaxies – a collection of billions of stars.
Hubble showed that the universe is much larger than our own galaxy. Today, we
know that the universe contains hundreds of billions of galaxies. That is about the
same number of galaxies as there are stars in the Milky Way Galaxy.
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Objective – After reading an article, I can identify characteristics of the universe.
Name ______________________________________________________________
How Big Is Our Universe?
Match the term with the definition
_____1. Distances
A. A force of attraction
_____2. Galaxy
B. A group of hundreds of billions of stars held
together by gravity.
_____3. Gravity
C. How far one object is from another,
_____4. Light-year
D. Huge balls of gas held together by gravity
_____5. Milky Way Galaxy
E. Our home galaxy.
_____6. Planets
_____7. Speed of light
F. Round balls of rock and/or gas that orbit a star,
have enough of their own gravity to become round.
_____87. Stars
G. The distance light travels in one year
H. The time it takes light to travel, about 186,000 miles
per second
9. The universe contains everything: all the stars, galaxies, gas, dust, planets, etc.
a. True
b. False
10. It takes a space probe ______ months to travel to Mars. (Enter a number.)
11. This is the fastest space probe every launched.
a. Cassini
b. Mariner 9
c. New Horizons
d. Voyager 2
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Objective – After reading an article, I can identify characteristics of the universe.
12. It took New Horizons ________ years to reach Pluto. (Enter a number; include
the decimal point!)
13. Earth is _______,000,000 miles away from the Sun. (Enter a two digit number!)
14. Earth is ______ light minutes from the Sun. (Enter a number; include the
decimal point!)
Match the number of seconds with the length of time.
_____15. Distance light travels in a year (miles) A. 31,536,000
_____16. Seconds per day
B. 5,865,696,000,000
_____17. Seconds per hour
C. 3,600
_____18. Seconds per year
D. 86,400
Place the planets/star in the proper order, 1 being the nearest, 10 being the farthest.
_____19. Alpha Centauri
A. 1
_____20. Earth
B. 2
_____21. Jupiter
C. 3
_____22. Mars
D. 4
_____23. Mercury
E. 5
_____24. Neptune
F. 6
_____25. Pluto
G. 7
_____26. Saturn
H. 8
_____27. Uranus
I. 9
_____28. Venus
J. 10
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Objective – After reading an article, I can identify characteristics of the universe.
29. The nearest star to Earth, Alpha Centauri, is _______ light years away. (Enter a
number; include the decimal point!)
30. The Milky Way Galaxy is about ______,000 light years across. (Enter a three
digit number!)
31. The Andromeda galaxy is about ______ million light years away. (Enter a
number; include the decimal point!)
32. Gravity holds the universe together.
a. True
b. False
33. The Greeks believed the Earth was the center of the universe.
a. True
b. False
34. Using a telescope, Galileo saw more _______ than you can see with just your eyes.
a. galaxies
b. moons
c. nebulae
d. stars
35. There are about the same number of galaxies in the universe as there are stars in
our galaxy.
a. True
b. False
Scoring Guide
95-100% - 4 75-84% - 2.5
90-94% - 3.5 65-74% - 2
85-89% - 3 55-64% - 1.5
45-54% - 1
1-44% - .5
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Objective – After reading an article, I can identify characteristics of the universe.
How Big Is Our Universe? – Key I
Match the term with the definition
_____1. Distances
A. A force of attraction
_____2. Galaxy
B. A group of hundreds of billions of stars held
together by gravity.
_____3. Gravity
C. How far one object is from another,
_____4. Light-year
D. Huge balls of gas held together by gravity
_____5. Milky Way Galaxy
E. Our home galaxy.
_____6. Planets
_____7. Speed of light
F. Round balls of rock and/or gas that orbit a star,
have enough of their own gravity to become round.
_____87. Stars
G. The distance light travels in one year
H. The time it takes light to travel, about 186,000 miles
per second
C 1. Distances
B 2. Galaxy
A 3. Gravity
G 4. Light-year
E 5. Milky Way Galaxy
F 6. Planets
H 7. Speed of light
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Objective – After reading an article, I can identify characteristics of the universe.
D 8. Stars
9. The universe contains everything: all the stars, galaxies, gas, dust, planets, etc.
a. True
b. False
a. True
10. It takes a space probe ______ months to travel to Mars. (Enter a number.)
9
11. This is the fastest space probe every launched.
a. Cassini
b. Mariner 9
c. New Horizons
d. Voyager 2
c. New Horizons
12. It took New Horizons ________ years to reach Pluto. (Enter a number; include
the decimal point!)
9.5
13. Earth is _______,000,000 miles away from the Sun. (Enter a two digit number!)
93
14. Earth is ______ light minutes from the Sun. (Enter a number; include the
decimal point!)
8.3
~9~
Objective – After reading an article, I can identify characteristics of the universe.
Match the number of seconds with the length of time.
_____15. Distance light travels in a year (miles) A. 31,536,000
_____16. Seconds per day
B. 5,865,696,000,000
_____17. Seconds per hour
C. 3,600
_____18. Seconds per year
D. 86,400
B 15. Distance light travels in a year (miles)
D 16. Seconds per day
C 17. Seconds per hour
A 18. Seconds per year
Place the planets/star in the proper order, 1 being the nearest, 10 being the farthest.
_____19. Alpha Centauri
A. 1
_____20. Earth
B. 2
_____21. Jupiter
C. 3
_____22. Mars
D. 4
_____23. Mercury
E. 5
_____24. Neptune
F. 6
_____25. Pluto
H. 7
_____26. Saturn
I. 8
_____27. Uranus
J. 9
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Objective – After reading an article, I can identify characteristics of the universe.
_____28. Venus
K. 10
J 19. Alpha Centauri
C 20. Earth
E 21. Jupiter
D 22. Mars
A 23. Mercury
H 24. Neptune
I 25. Pluto
F 26. Saturn
G 27. Uranus
B 28. Venus
29. The nearest star to Earth, Alpha Centauri, is _______ light years away. (Enter a
number; include the decimal point!)
4.3
30. The Milky Way Galaxy is about ______,000 light years across. (Enter a three
digit number!)
100
31. The Andromeda galaxy is about ______ million light years away. (Enter a
number; include the decimal point!)
2.5
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Objective – After reading an article, I can identify characteristics of the universe.
32. Gravity holds the universe together.
a. True
b. False
a. True
33. The Greeks believed the Earth was the center of the universe.
a. True
b. False
a. True
34. Using a telescope, Galileo saw more _______ than you can see with just your eyes.
a. galaxies
b. moons
c. nebulae
d. stars
d. stars
35. There are about the same number of galaxies in the universe as there are stars in
our galaxy.
a. True
b. False
a. True
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Objective – After reading an article, I can identify characteristics of the universe.
How Big Is Our Universe? – Key II
1. C (8 choices)
2. B (8 choices)
3. A (8 choices)
4. G (8 choices)
5. E (8 choices)
6. F (8 choices)
7. H (8
choices)
8. D (8 choices)
9. a (2 choices)
10. 9
11. c
12. 9.5
13. 93
14. 8.3
15. B
16. D
17. C
18. A
19. J (10 choices)
20. C (10 choices)
21. E (10 choices)
22. D (10 choices)
23. A (10 choices)
24. H (10 choices)
25. I (10 choices)
26. F (10 choices)
27. G (10 choices)
28. B (10 choices)
29. 4.3
30. 100
31. 2.5
32. a (2 choices)
33. a (2 choices)
34. d
35. a (2 choices)
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Objective – After reading an article, I can identify characteristics of the universe.
How Big Is Our Universe?
Scoring Guide
33-35 – 4
32 – 3.5
30-31 – 3
26-29 – 2.5
23-25 – 2
19-22 – 1.5
16-18 – 1
1-15 – .5
0–0
95-100% - 4
90-94% - 3.5
85-89% - 3
75-84% - 2.5
65-74% - 2
55-64% - 1.5
45-54% - 1
1-44% - .5
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