TELESCOPES
Telescopes
 Write
what is in YELLOW
 You will be accountable for
text in yellow on quizes.
Where do we put telescopes to have the
best viewing conditions?
1. On Earth:
CLEAR
HIGH
DRY
COLD
DARK
Problem with Telescopes on Earth?
Problem:
Particles of all sorts in the atmosphere block and cloud
the view
2. In Space
Solves atmosphere problem –
CLEAR VIEW!
Examples: Hubble, Cobe , Iras
Problem with telescopes in space?
They’re in space!
Hard to get to
Hard to repair
EXPENSIVE!!!
Functions of a Telescope
1.
2.
3.
4.
Collect Light
Magnify Images
Separate Distant Objects
Use as a Camera
I. OPTICAL TELESCOPES
(USE VISIBLE LIGHT)
Two types:
1. Refractor –
BENDS LIGHT
Invented by Hans Lippershey in 1608
Refined by Galileo in 1609
Galileo demonstrating his telescope
Tololo Observatory - Chile
TYPE 1 – REFRACTING TELESCOPE
How does it work?
a.
b.
It bends light to create an image
It uses two lenses
1. eyepiece (ocular) lens - small
2. objective lens - large
Draw it!
Type 2 – Reflecting
Telescope
a.
Invented by Isaac Newton in 1668
b.
Uses two mirrors
Objective Mirror – Large
Secondary (flat) mirror – Small
c. Can be VERY LARGE 40 ft - 50 ft
diameter objective mirror!
2. Reflector –
USES MIRRORS
Cheap and common
Draw It!
Most Modern Telescopes
combine technologies
A.
Examples
a.
b.
Hubble
Kepler http://kepler.nasa.gov/
Advantages of a reflector
1.
only one side of the mirror.
A.
2.
(on a refractor the lens has two sides) –
cheaper and distortion is less of a problem.
The whole back of the mirror can be
supported, therefore can be made very
LARGE
II. Non-optical Telescopes
1.
Radio Telescopes
a. Location – Earth
(atmosphere does not affect radio waves)
b. Structure – Large metal dish
c. Size – very large because radio waves
have a very long wavelength
d. Arrays – sets of multiple radio
telescopes that allow for more data to be
gathered.
Ex –
VLA (very large array) in Socorro, New Mexico
27 dishes.
SETI– Search for Extra-Terrestrial Intelligence
looking for intelligent radio signals
Other Non-Optical Telescopes
(all are satellites)
2. Infrared – IRAS launched 1983
3. Microwaves – COBE
Cosmic Background
explorer. Discovered evidence of the Big Bang.
Launched 1981
COBE Image of CBR
4. X-Rays – Chandra Launched 1999
Cassiopeia Super Nova
Black Hole
Crab Nebula
Saturn
5. Gamma Rays –
Observatory
GRO Gamma Ray
Milky Way