November 09, 2020

#08-007: The Telescope

Galileo holding a telescope

Note: One important part of the technological advancement of humankind is the development of tools that allow us to make even further discoveries. For example, astronomy took a great leap forward with the development of the telescope in the 17th century.

Get Ready: Have you ever looked through a telescope (or binoculars)? If you have, what was it like? If you haven't, what do youthink it would be like?

A telescope does exactly what its Greek name tells us: tele- means "far," and -scope means "look at; view." A telescope allows someone to look at something that is far away.

When we think of telescopes, most of us picture the optical kind, which focus visible light from far away. But there are many others, using wavelengths from radio, microwave, and infrared waves (longer than visible light) all the way to ultraviolet, X-rays, and gamma rays at the shorter end of the electromagnetic spectrum.

But the optical telescope preceded all of these, and the original, refracting instruments (which "bend" the direction of light) were quite simple: essentially, two lenses, mounted in either end of a tube. The first appearance of these devices on the scene was in 1608 when a Dutch spectacle-maker named Hans Lippershey tried to patent one.

One story accounting for Lippershey's "discovery" has two children playing with lenses in his shop, and exclaiming that if they held them correctly, they could see a distant weathervane more closely. More likely, Lippershey was just replicating a common idea of the time.

But Lippershey was not successful in his patent application because other lens makers were producing the same thing! Just a year later the eminent Italian astronomer Galileo Galilei (who may have heard of Lippershey's work) had invented an improved version of the device.

Simple as it was, Galileo was able to use his telescope for an astonishing range of discoveries, among them the four largest moons of Jupiter (Io, Europa, Ganymede, and Callisto, called the "Galilean moons"), and the fact that the planet Venus has phases not unlike those of our moon, stating that "The mother of love [Venus] imitates the shape of Cynthia [the moon]."

Galileo's telescopes never exceeded a 30x magnification, and could be used for observing things on earth as well as in the heavens (this is called a "terrestrial telescope" or "spyglass"). Telescope making became something of a lucrative sideline for Galileo, who sold his instruments to merchants for use at sea and as items of trade.


Read more:

Practice: Match the term to its definition below:

  1. astonishing
  2. exceeded
  3. lucrative
  4. optical
  5. sideline
  6. spectacle-maker
  7. terrestrial
  8. the electromagnetic spectrum
  9. weather-vane
  10. x

  1. amazing
  2. profitable; moneymaking
  3. one who makes eye-glasses
  4. of the earth
  5. related to vision and the science of optics
  6. a secondary business interest
  7. meaning "times" or "by"
  8. a device for indicating the direction of the wind
  9. the continuum of all kinds of radiation
  10. went beyond

Answers are in the first comment below.

Submitted to the Shenzhen Daily for November 9, 2020

1 comment:

  1. Answers to the Practice: 1. a; 2. j; 3. b; 4. e; 5. f; 6. c; 7. d; 8. i; 9. h; 10. g