Part 4: Development of the Telescope
Section 4
Question 31-40
Complete the notes below.
Write ONE WORD ONLY for each answer.
| The development of the telescope |
Roger Bacon (1200s)
• His invention assisted 31 …………………………….. With sight problems when they were reading
Lipperhey
• 1680: he put concave and convex lenses together to create the telescope
• The small telescope was first use in 32 ………………………………
Galileo
• 1609: he tried out different lenses to improve the telescope
• He started 33 ………………………. of the lenses he needed
The venetian government hoped to use this instrument for the 34 …………………………….. |
Galileo’s astronomical discoveries
• The Moon
– he discovered its surface was mountainous
– he worker out the height of the mountains by identifying spots that were 35 ………………..
– he created 36 ……………………………….. of the moon’s surface
• Jupiter
– realized that the bodies orbiting Jupiter were not 37 ……………………………….. But moons.
Further development
• Scientists discovered that increasing the telescope’s 38 ………………………….. Improved its power.
• 1670: Hevelius built a telescope 43 meters long.
– poor results: the telescope will would move with the 39 ………………………………
– the problem was solved by attaching it to a 40 …………………………… |
Key
- researchers
- theatre/ theater
- production
- army
- bright
- charts
- stars
- length
- wind
- building
Transcript
Lecturer: Good morning. Today’s lecture is about the development of the telescope up until the end of the 17th century.
Early Inventions (1200s – 1608)
Lecturer: We can trace the telescope’s
earliest form back to the 1200s. History records Roger Bacon as possibly the first to invent a magnifying glass. The principal use of his invention was for reading. This proved to be a benefit mostly for researchers who, until then, had been forced to give up working while still relatively young because of impaired vision.
In 1608, a Dutch astronomer called Lieberhei discovered that if convex and concave lenses were put together, they created a magnifying glass through which things at a distance could be seen. He created a miniature telescope. It was so small that, initially, people took it to the theater for a better view of the stage.
Galileo’s Improvements and Discoveries (1609 – 1610)
Lecturer: Galileo found out about Lieberhei’s invention in the spring of 1609 and immediately set about improving it.
Instrument Improvement
- Galileo experimented with different lenses, combining a weak convex lens with a strong concave lens. He discovered that this intensified the strength of the instrument.
- Unfortunately, the lenses the opticians were making for glasses were unsatisfactory for what Galileo wanted to do, as they did not have powerful enough magnification.
- Galileo, therefore, decided that, to solve his problem, he would have to start the production of his own lenses.
- Eventually, he achieved a magnification about nine times more than you could see with the naked eye, an enormous improvement over everything else on the market.
Demonstration and Recognition
- Galileo then decided to approach the Senate of Venice to demonstrate the improved instrument.
- Many senators were eager to try the new telescope and climbed the highest bell towers in Venice to look through the glass at ships far out to sea.
- The government of Venice were impressed by his invention’s obvious potential, and envisioned the advantages this eyeglass could have for the army.
Discovery 1: The Moon
- His first major astronomical discovery with the telescope was that the moon’s surface was mountainous, and not a perfect sphere as it had always been assumed.
- During the lunar cycle of 28 days, he found that the shadows seemed to vary with the light.
- Galileo also figured out how to estimate the altitude of the mountains on the moon by looking for bright spots in the dark areas.
- He looked for the spots when it was a half moon and, with geometry, was able to calculate the elevation of the mountains.
- From these calculations, he was able to draw charts of the terrain and show the altitudes of the mountains.
Discovery 2: Jupiter’s Moons
- In 1610, Galileo’s next major discovery was regarding Jupiter.
- Using a magnification telescope 20 times the strength of his previous ones, he looked at Jupiter on successive nights.
- His main observation was a trio of what initially seemed to be small stars close to Jupiter.
- However, by the 15th night, he realized that they were going around the planet in a daily orbit. And that, in fact, they were moons, not stars. And three days later, he saw a fourth one.
- This discovery showed how important a telescope was for astronomers. They would now be able to see celestial objects that could not previously be seen by the naked eye.
Later 17th Century Developments
Lecturer: In the later 1600s, scientists started to make a stronger telescope, revealing the galaxy. Scientists realized that when they increased the length of the telescope, the intensity of magnification improved significantly.
- One such telescope was created in 1656 and magnified over 100 times. It had the incredible length of 4 meters.
- Telescopes continued to become longer over the next few years. And, in fact, the astronomer, Haverius, built one in 1670 that was 43 meters long.
- However, these telescopes were soon to prove useless for accurate observation, because the slightest wind caused the instrument to shift.
- Finally, in 1675, astronomers abandoned the tube telescope and instead mounted the telescope on a building. Telescopes like this were called aerial telescopes.
- Scientists hoped that the stability of the mount would decrease the frustration when observing stars.
Lecturer: Well, that’s about it for today, and so I…
