Lecture 8: Telescopes II
1. Resolution and “seeing”? how sharp a picture you can make
2. Examples of non-optical telescopes: radio and X-ray
3. Why do we go to space? better resolution, no atmospheric extinction
Optical reflecting telescopes
12 inch, backyard telescope
Optical reflecting telescopes
1 meter professional telescope
Optical reflecting telescopes
secondary mirror
primary mirror
focus
2.5 meter telescope (du Pont)
Optical reflecting telescopes
secondary mirror
primary mirror
6.5 meter telescope (Magellan)
Optical reflecting telescopes
Subaru 8.2m telescope
Keck 10m telescope (one of a pair)
Optical reflecting telescopes
this one DOESN’T EXIST YET (24 meter Giant Magellanic Telescope)
“Resolution”
BECAUSE THEY CAN
COLLECT MORE LIGHT
What sets the resolution?
Diffraction limit:
Atmospheric disturbances
(“seeing”):
“Seeing”
BECAUSE THEY CAN
COLLECT MORE LIGHT
“Adaptive optics”
“Adaptive optics”
What about non-optical telescopes?
Green Bank Telescope
(100m radio dish)
What about non-optical telescopes?
Green Bank Telescope
(100m radio dish)
What about non-optical telescopes?
Green Bank Telescope
(100m radio dish)
What about non-optical telescopes?
Green Bank Telescope
(100m radio dish)
Space telescopes
Hubble Space Telescope
Space telescopes
GALEX UV satellite
Space telescopes
Spitzer Space Telescope (infrared)
Example: spectra of very distant galaxies
Magellan 6.5m telescope, at Las
Campanas Observatories in Chile
Example: spectra of very distant galaxies
Direct image
These objects are
typically about
1,000,000 times
fainter than you
can see with the
unaided eye
Example: spectra of very distant galaxies
insert mask,
designed to have
holes located to let
the light of
galaxies through
that we are
interested in
Example: spectra of very distant galaxies
insert mask,
designed to have
holes located to let
the light of
galaxies through
that we are
interested in
Example: spectra of very distant galaxies
insert mask,
designed to have
holes located to let
the light of
galaxies through
that we are
interested in
Example: spectra of very distant galaxies
insert mask,
designed to have
holes located to let
the light of
galaxies through
that we are
interested in
Example: spectra of very distant galaxies
Insert prism to
obtain spectrum
of each object
Example: spectra of very distant galaxies
Insert prism to
obtain spectrum
of each object