1. TELESCOPES ALLOW US TO STUDY SPACE FROM EARTH!!!

2. History Galileo Galilei (1564-1642)
1st telescope invented in Holland in 1609
Galileo learned of this and made his own: small 30X scope
Observed the moon and “began” the modern age of Astronomy where measurement was more important than philosophy

3. Galileo noticed moons orbiting Jupiter phases of Venus
craters on the moon
Sunspots
Old Model = geocentric
Current Model = heliocentric
This was strong evidence that Copernicus was right although Galileo wasn’t willing to die for it. The sun was the center of the solar system!

4. Lenses
The lens in your eyes works like a glass lens. The light bends as it goes through a different medium.
Light rays are bent when they intersect glass; a curved surface can produce an image.
In your eye, the image is then focused at the retina.

5. How does this apply to telescopes?
If you had a bigger eye, you could collect more light from the object. This image could be magnified so it stretches out over more pixels in your retina.
In a telescope, two pieces make this possible:
the objective lens (refractor telescopes) or primary mirror (reflecting telescopes)
the eye piece

6. Not everything is visible…
Many modern day telescopes do not use visible light to collect images.
Radio telescopes, x-ray telescopes and infrared (IR) telescopes have become a staple of modern day astronomy, producing some amazing images.

7. How a telescope works
TELESCOPE: a device that gathers electromagnetic radiation
VISIBLE LIGHT TELELSCOPES
REFLECTING TELESCOPE
REFRACTING TELESCOPE
Uses a mirror to collect light
Light bounces off 2 different mirrors Newton’s Telescope
Uses a glass lens to collect light light travels in a straight line Galileo’s telescope

8. Famous Optical Telescopes on Earth
Keck Telescope-Mauna Kea Hawaii Mirror is 10 meters wide
Kitt Peak Observatory Tuscon, AZ

9. RADIO TELESCOPES
Show where radio waves are being emitted by objects in space
Has a dish & antenna ; Need to very BIG because radio waves are so long
Very little interference
Very Large Array (VLA) radio telescopes in New Mexico, signals are combined to produce clearer images

10. Problems with earth-based telescopes
Earth’s atmosphere reflects certain wavelengths
x-rays, gamma rays and most UV light is not transmitted by our atmosphere
Earth’s atmosphere blurs images
the bending of light by the atmosphere depends on the temperature of the “air”
“twinkling” (shimmering) effect
“Light pollution”
Solution? Put the telescope in space. HUBBLE

11. Light Absorbed by Earth’s Atmosphere

12. Telescopes in SPACE Hubble Space Telescope-reflecting telescope
Placed in orbit in 1990
Collects visible light, infared, & ultraviolet
Chandra X-ray Observatory 1999
Compton Gamma-Ray Observatory 1991
Spitzer (infared) 2003

13. Disadvantages of space-based telescopes
Expensive to launch and maintain
Difficult to repair
Low lifetime
Spitzer
Jame Webb Telescope 2014