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Telescopes II

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To achieve good angular resolution, radio telescopes need to have very ... SOFIA. Spitzer. Infrared. Remember that we emit infrared radiation. As does the Earth ... – PowerPoint PPT presentation

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Title: Telescopes II


1
Telescopes II
  • Dr Bryce

2
Class Notices
  • Homework due at 5pm

3
Observing non-visible light
  • A standard satellite dish is essentially a
    telescope for observing radio waves

4
Radio Telescopes
  • A radio telescope is like a giant mirror that
    reflects radio waves to a focus

5
Radio telescopes
  • To achieve good angular resolution, radio
    telescopes need to have very large diameter
  • Hundreds of meters
  • Thankfully the surface doesnt need to be
    completely smooth
  • Although there is no light pollution but our
    communications are much louder than many
    astronomical sources

6
IR UV Telescopes
SOFIA
Spitzer
  • Infrared and ultraviolet-light telescopes operate
    like visible-light telescopes but need to be
    above atmosphere to see all IR and UV wavelengths

7
Infrared
  • Remember that we emit infrared radiation
  • As does the Earth
  • Even in space an infrared telescope needs a lot
    of cooling

8
UV
  • Much of the UV range behaves like visible light
    and can be collected by a mirror
  • However extremely short wavelength and X-rays
    cannot be focused by mirrors, they require a nest
    of metal cones to focus the light using grazing
    incidence.

9
Gamma Ray Telescopes
  • Gamma ray telescopes also need to be in space
  • Focusing gamma rays is extremely difficult
  • We cannot locate the source of the rays without
    using other wavelengths

Compton Observatory
10
Interferometry
  • Interferometery is a technique for linking two or
    more telescopes so that they have the angular
    resolution of a single large one

11
Interferometry
  • Easiest to do with radio telescopes
  • Now becoming possible with infrared and
    visible-light telescopes

Very Large Array (VLA)
12
VLA
13
VLBA
14
The Sun
  • Chapter 14
  • (Yes we are skipping the missing chapters)

15
Is it on FIRE?
Chemical Energy Content
10,000 years
Luminosity
16
Is it CONTRACTING?
Gravitational Potential Energy
25 million years
Luminosity
17
E mc2 - Einstein, 1905
It can be powered by NUCLEAR ENERGY!
Nuclear Potential Energy (core)
10 billion years
Luminosity
18
Weight of upper layers compresses lower layers
19
Gravitational or Hydrostatic equilibrium Energy
provided by fusion maintains the pressure
20
Gravitational contraction Provided energy that
heated core as Sun was forming Contraction
stopped when fusion began
21
Radius 6.9 x 108 m (109 times Earth) Mass
2 x 1030 kg (300,000 Earths) Luminosity
3.8 x 1026 watts
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