Cassegrain Telescope

1
Cassegrain Telescope

• Uses mirrors but now focuses image at end rather
  then on side

2
Modern Telescopes Smithsonian Observatory

• 6.5 m telescope
• Observatory location Mount Hopkins, Arizona, USA
  
• Altitude 2606 meters

3
Modern Telescopes Very Large Telescope (VLT)

• Largest optical telescope on earth
• Observatory location Cerro Paranal, northern
  Chile
• Height above sea level 2,635 meters
• Mirror diameter 8.2 meters /26.58 feet
• Mirror thickness 175mm

4
Modern Telescopes Keck Telescope in Hawaii on
Mauna Kea houses several telescopes of various
size

5
Hubble Space Telescope

• Launched 1990, repaired in 1994
• First large optical telescope in space
• 2.4 m primary mirror
• weblink

6
Non-visible wavelength telescopes

• Why do we look at other wavelengths
• new information not contained in visible portion
  of spectrum
• Visible light only tiny portion of the entire
  spectrum

7
Radio Telescopes

• Arecibo radio telescope (Puerto Rico)
• huge "dish" is 305 m (1000 feet) in diameter,
  167 feet deep, and covers an area of about twenty
  acres

8
Radio Telescopes

• Very Large Array
• consists of 27 radio antennas in a Y-shaped
  configuration on the Plains of San Agustin fifty
  miles west of Socorro, New Mexico. Each antenna
  is 25 meters (82 feet) in diameter.

9
X-Ray Observatory

• Chandra-

10

• Motion of moon and phases (see p 56)

11
Lunar eclipse

• Q if moon is smaller then sun how can it block
  the sun?

12

• Solar Eclipse
• Total Solar Eclipses occur when the umbra of the
  Moon's shadow touches a region on the surface of
  the Earth.
• Partial Solar Eclipses occur when the penumbra of
  the Moon's shadow passes over a region on the
  Earth's surface.
• Annular Solar Eclipses occur when a region on the
  Earth's surface is in line with the umbra, but
  the distances are such that the tip of the umbra
  does not reach the Earth's surface.