Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
The work of astronomers Copernicus, Brahe, and Kepler was amazing. They did all their
observations of the night sky using their eyes. The invention of the telescope allowed scientists
to “extend their senses” for the first time. The telescope is one of the most important tools
used by astronomers.
Who Invented the Telescope?
We don’t know who invented the telescope. One
story is that two children were playing with lenses in
the shop of Hans Lippershey, a Dutch readingglasses maker. The children looked at a nearby
weather vane through two lenses held together. It
became larger and clearer. Lippershey put a tube in
between the two lenses. This may have been one of
the first telescopes. This early model only magnified
an image by three or four times. A marble would have appeared three or four times larger than its
actual size.
Lippershey tried to sell his telescope. In 1608, he applied for a patent on his telescope. This would
protect his idea from being stolen by someone else. He was required to make three identical
telescopes and to keep his method secret. Making more was not a problem. He had trouble keeping
his secret. Jacob Metius applied for a patent on a device for “seeing faraway things as though
nearby.” His device was a tube with one convex lens (curved outward) and one concave lens that
curved inward.
Government officials discussed the patent applications of both men. Neither man received a
patent. The telescope design was easily copied. The patent request was refused. They did give
Metius a small amount of money and paid Lippershey to make several telescopes. Hans
Lippershey is given credit for inventing the telescope.
~1~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
These looked more like “spyglasses” than our modern telescopes. Because they used lenses that
refracted (or bent) light, they were called refractor telescopes.
Galileo Received Credit for the Refractor Telescope
In 1609, Galileo heard Lippershey was on his way to
Venice. He planned to sell his invention that “that made
distant objects seem near.” He needed money. He knew
the Venetians were offering Lippershey a high price for
his device. In 24 hours, Galileo had a telescope made. He
sent word of “his invention” to a monk in a high office of
the government. For this, Galileo received a raise in salary
from 520 to 1000 florins per year.
We know three things about the invention of the telescope.
 First, telescopes were not invented by scientists. They were invented by craftsman.
 Second, Galileo did not invent the telescope.
 Finally, telescopes changed astronomical observation. Scientists relied upon larger
and better telescopes to continue their study of the heavens.
Galileo used a telescope with lenses that magnified objects about 20 times their size. With this
telescope, he discovered the moons of Jupiter, the rings of Saturn, the changing apparent
shape of Venus, Sunspots, and solar rotation in less than ten years. During the same decade,
at least ten other astronomers built their own telescopes using different combinations and types of
lenses. Many of these were used to verify, support, and extend Galileo’s discoveries.
Early Refractor Telescopes Reached Their Limits
There were several problems with Galileo’s telescopes. They only allowed for a narrow field of
view (what could be seen). The images produced through the lenses were blurry. Around
1630, a German astronomer, Johannes Kepler, proposed some solutions. To expand the area that
could be visible through a telescope, Kepler suggested the concave eyepiece be replaced by a
convex one. This design produced an upside-down image. It was corrected by the two-convex lens
design. He discovered that by flattening the shape of the lens, the image quality could be improved.
This solution caused a problem. With a flatter lens, the only way to increase the magnification
power of the telescopes was to increase the length of these telescopes. By the middle of the
~2~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
17th century, the length of telescopes became longer and longer. They were eventually were
too large to control.
Isaac Newton Built a Reflector Telescope
Another problem was that the glass lenses caused light to separate into colors. You may have
observed how a glass prism creates a rainbow effect. The early telescope lenses produced a ring of
color around bright objects. This is called chromatic aberration. An English scientist, Sir Isaac
Newton, solved this problem by using metal mirrors instead of glass lenses. This design
solved the “color” problem. Better yet, it was six inches long. It could magnify objects 40 times.
Some of the best reflector telescopes were designed and built by William Herschel. He built
a telescope that was used by Johann Schröter, the president of the “Celestial Police.” This group
was formed to search for and discover the “missing planet.” Astronomers believed it would be
found between the orbits of Mars and Jupiter.
Images continued to be blurry with the early reflector telescopes. Technology finally made it
possible to grind the lenses and mirrors into different shapes. Newton’s design led to a new
problem. The metal mirror became dull easily. It required frequent polishing. Even so, the
introduction of the reflecting telescope inspired a new surge of astronomical discoveries. Scientific
pursuits continued to inspire improvements to the telescope.
In those days spirits were brave, the stakes were high, men were real men, women were real women and small furry
creatures from Alpha Centauri were real small furry creatures from Alpha Centauri.
― Douglas Adams, The Hitchhiker's Guide to the Galaxy
~3~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
Worksheet
1. Why were the work of astronomers Copernicus, Brahe, and Kepler remarkable?
a. They were the first to use a telescope.
b. All their observations were made using their eyes.
c. They took photographs through a telescope.
d. They worked together to answer astronomical questions.
2. The telescope is considered one of the most important instruments in the Scientific Revolution
of the 17th century.
a. True
b. False
3. While nobody knows who invented the telescope, who is usually considered to have been a
possible inventor?
a. Tycho Brahe
b. Galileo
c. Hans Lippershey
d. Baron von Steuben
4. Who is given credit for inventing the refractor telescope?
a. Tycho Brahe
b. Galileo
c. Hans Lippershey
d. Baron von Steuben
5. There are three things certain about the invention of the telescope. Which statement below is not
one of the three?
a. First telescopes were invented by craftsman.
b. Galileo did not invent the telescope.
c. Telescopes change astronomical observations.
d. Telescopes were not widely accepted until the 18th century.
~4~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
6. Which was not a discovery made by Galileo?
a. The Moons of Jupiter.
b. Channing shape of Venus.
c. The division in Saturn’s rings.
d. Sunspots and solar rotation.
7. What were problems with Galileo’s telescopes?
a. Allowed for a narrow field of view (what could be seen).
b. They were not portable.
c. Images were blurry.
d. Both a and b.
e. Both a and c.
f. Both b and c
8. Why did refractor telescopes become too large to control?
a. They weighed too much.
b. They became longer and longer.
c. They were too tall.
d. The lenses were too large.
9. What did Sir Isaac Newton use instead of lenses in his reflecting telescope?
a. Prisms
b. Glass mirrors.
c. Lights
d. Metal mirrors
10. Who built some of the best reflector telescopes?
a. Sir Isaac Newton
b. William Herschel
c. Johann Schröter
d. George Gamov
~5~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
Seeing Faraway Things as Though Nearby – Key
1. Why were the work of astronomers Copernicus, Brahe, and Kepler remarkable?
b. All their observations were made using their eyes.
2. The telescope is considered one of the most important instruments in the Scientific Revolution
of the 17th century.
a. True
3. While nobody knows who invented the telescope, who is usually considered to have been a
possible inventor?
c. Hans Lippershey
4. Who is given credit for inventing the refractor telescope?
b. Galileo
5. There are three things certain about the invention of the telescope. Which statement below is not
one of the three?
d. Telescopes were not widely accepted until the 18th century.
6. Which was not a discovery made by Galileo?
c. The division in Saturn’s rings.
7. What were problems with Galileo’s telescopes?
e. both a and c.
8. Why did refractor telescopes become too large to control?
b. They became longer and longer.
~6~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
9. What did Sir Isaac Newton use instead of lenses in his reflecting telescope?
d. Metal mirrors
10. Who built some of the best reflector telescopes?
b. William Herschel
~7~
Objective – Describe the history of asteroid discovery and how technology was used to learn about the asteroids.
Seeing Faraway Things as Though Nearby – Scoring Guide
1. b
2. a (2 choices)
3. c
4. b
5. d
6. c
7. e (6 choices)
8. b
9. d
10. b
Scoring Guide
9-10 – 3
8 – 2.5
7–2
6 – 1.5
5–1
1-4 – .5
0–0
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