1. The Solar System:
A6: Telescopes

2. The Telescope
Telescope – device that makes distant object appear closer
A Dutch lens maker, Hans Lippershey, invented the telescope in 1608
Galileo made it famous in 1610 when he used it to see objects in the night sky
Galileo was the first person to ever see sun spots, Saturn’s rings, and the large moons of Jupiter

3. Electromagnetic Radiation
To understand how a telescope works, it is useful to understand the nature of electromagnetic radiation
Forms of Radiation – energy that travels through space in waves
Visible Light – Light that can be seen is one type of electromagnetic radiation
Other types of radiation include: radio waves, x-rays, gamma rays, and more

4. Electromagnetic Radiation
Electromagnetic Spectrum – includes the entire range of visible and non-visible waves
Recall, a wave length is the distance from the crest of one wave to the crest of the next
Also recall that wave lengths increase towards the red end of the spectrum
Draw in your notes
In which direction does the energy increase?

5. Types of Telescopes
Optical Telescopes – use lenses or mirrors to collect and focus light making objects appear larger and brighter
Refracting Telescope – uses convex lenses
Convex Lens – clear glass curved so that the middle is thicker than the edges
A simple refracting telescope, like the one Galileo used, has two convex lenses at the ends of a long tube

6. Types of Telescopes Light enters through the larger objective lens
The objective lens focuses the light a certain distance from the lens
That distance is the focal length of the lens
The smaller lens is the eyepiece
The eyepiece lens magnifies the image produced by the objective lens

7. Types of Telescopes
Reflecting Telescope – uses a curved mirror to collect and focus light
Invented in 1668 by Isaac Newton
Instead of an objective lens, the mirror focuses the light
They can be made much bigger
Less optical irregularities and brighter images
All the largest telescopes today are reflecting

8. Other Types of Telescopes
Other Types of Telescopes – collect and focus different types of electromagnetic radiation (instead of visible light)
Radio Telescope – Curved, reflecting surfaces used to detect radio waves.
Surface reflects and concentrates radio waves like a mirror in a refracting scope
The concentrated waves are projected onto a small antenna
The larger the curved surface is, the more waves it can collect

9. Other Telescopes
Infrared Telescope – Use infrared light to detect celestial bodies
They contain a camera and a special solid-state infrared detector which must be cooled to cryogenic temperatures
Can be ground-based, air-based, or in space
Because water vapors in the air absorb infrared, ground-based scopes are usually on mountains in very dry climates
Putting them in space eliminates the atmosphere’s interference

10. Other Types of Telescopes
Other Telescope – Other types of telescopes include ultraviolet, x-ray, and gamma ray scopes
To understand how the images of the telescopes differ, below are pictures of the Crab Nebula taken with each.
Video

11. In Closing Why do you think telescopes were first invented?
Why are telescopes important to the study of astronomy?