Telescopes for all types

#1 Reflecting and Refracting telescopes work differently

#2 Telescopes are found in strange places

#3 Radio telescopes work very differently

Big Ideas

Why cant you see an object that is far away?

Aperture- size of bucket- most important

Magnification- size of image

How much better is a 10-m telescope than a 2-m one?

a) Its 5 times better b) Its 10 times better c) Its 25 times better d) It's 50 times better

Big Idea #1

Reflecting and Refracting telescopes

work differently

Refracting Telescope- lens is the

main bucket and focal

length approx length of tube

Refracting telescopes have problems including

Choromatic abberation

Weight of lens

Size of telescope

Reflecting telescopes can have much greater diameters

SALT

8m10m 10m

8m

10m

4m

1m

Mirrors in reflecting telescopes can be segmented

SALT is the largest optical

telescope

Giant Magellan Telescope

(GMT) is being built

Given the choice of buying a 20cm refracting telescope and a 13cm reflecting telescope, which

would you choose and why?

Big Idea #2

Telescopes are found in strange

places

Atmospheric absorption determines telescope location

Wavelength

Where do we put optical telescopes?

Calm, High, Dark, Dry

remote mountains:HawaiiAndesAntarctica

Summit of Mauna Kea, Hawaii

Light pollution is increasingly problematic

Turbulence in our atmosphere distorts our view, causing stars to appear to twinkle, called seeing

same star viewed with Hubble Space Telescope

bright star viewed with ground-based telescope

Mid-latitude Antarctica Mid-latitude 2.5x

Antarctica is nearly as good as space

Lasers create artificial stars

to correct seeing:

adaptive optics

Imag

ing

ove

r ti

me

Bullets of Orion

Infared telescopes have to get away from the water

Big Idea #3

Radio telescopes work very differently

Radio telescopes

observe continuum radiation

and specific lines

A 21cm map of the galaxy

An

arti

s ts

imp

r ess

ion

of

the

Milk

y W

ay

Radio telescopes can be combined to make effectively bigger ones

Radio telescopes are isolated

The local inter-

feromter is the

MERLIN network

SKA will be the largest interferometer

Calm and isolated

are more important

for big dishes

a) An optical telescope in Snowdoniab) A radio telescope near Manchesterc) An IR telescope anywhere in the UK

You can fund one of these telescopes, which would you choose and why?

#1 Reflecting and Refracting telescopes work differently

#2 Telescopes are found in strange places

#3 Radio telescopes work very differently

Big Ideas

Slide 1Slide 2Slide 3Slide 4Thought Question How does the collecting area of a 10-m telescope compare with that of a 2-m one?Slide 6Slide 7Refracting TelescopeSlide 9Reflecting TelescopeSlide 11Mirrors in Reflecting TelescopesSlide 13Slide 14Slide 15Slide 16Slide 17Telescopes & the atmosphereSlide 19How does Earths atmosphere affect ground-based observations?Calm, High, Dark, DryLight PollutionTwinkling & turbulenceSlide 24Adaptive Optics (AO)Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31A 21cm map of the galaxySlide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40