Telescopes

1
Telescopes

• Chapter 5
• April 16,2010

2
Telescope Design

• There are two types of optical telescopes
• Reflecting-uses a curved mirror to gather and
  concentrate a beam of light
• Refracting-uses lens instead of a mirror to focus
  incoming light

3
Refraction telescopes

• The objective in a refracting telescope refracts
  or bends light.This refraction causes parallel
  light rays to converge at a focal point while
  those which were not parallel converge upon a
  focal plane.

4
Refraction Telescopes
5
Types of Reflection Telescopes

• Newtonian
• Cassegrain

6
Newtonian Telescopes

• Newtonian telescope-light is intercepted before
  it reaches the prime focus, and then deflected by
  90 degrees
• Smaller design, preferred by amateur astronomers
  

7
Cassegrain Telescopes

• The Cassegrain reflector is a combination of a
  primary concave mirror and a secondary convex
  mirror

8
Reflection Telescope
9
Hubble Telescope

• Hubble works on the same principle as the first
  reflecting telescope built in the 1600s by Isaac
  Newton.

10
Hubble Telescope

• Light enters the telescope and strikes a concave
  primary mirror, which acts like a lens to focus
  the light. The bigger the mirror, the better the
  image.

11
Hubble Telescope

• In Hubble, light from the primary mirror is
  reflected to a smaller secondary mirror in front
  of the primary mirror, then back through a hole
  in the primary to instruments clustered behind
  the focal plane (where the image is in focus).

12
(No Transcript)
13
Mirror Size on Hubble Telescope

• Primary mirror-2.4 meters (94.5 inches) in
  diameterSecondary mirror-0.3 meters (12 inches)
  in diameter

14
Angular resolution

• Hubble's angular resolution is 0.05 arcsecond.
  This is the "sharpness" of Hubble's vision. If
  you could see as well as Hubble, you could stand
  in New York City and distinguish two fireflies, 1
  m (3.3 feet) apart, in San Francisco

15
Facts about Hubble Telescope

• Hubble weighs 24,500 pounds -- as much as two
  full-grown elephants.
• During its lifetime Hubble has made about 800,000
  observations and snapped about 500,000 images of
  more than 25,000 celestial objects

16
Chandra X-Ray Observatory

• Launched on July 23, 1999
• This is an X-Ray Telescope
• Designed to observe X-rays from high-energy
  regions of the universe, such as the remnants of
  exploded stars

17
Comparison of Crab Nebula
18
Tracking Chandra

• The Space Shuttle Columbia delivered Chandra to a
  low Earth orbit. Then, the Inertial Upper Stage
  rocket boosted Chandra up to a higher altitude
  where a built-in propulsion system took Chandra
  to its final orbit. This elliptical orbit takes
  the spacecraft to an altitude of 133,000 km -
  more than a third of the distance to the moon -
  before returning to its closest approach to the
  Earth of 16,000 kilometers

19
Chandras Orbit

• It takes approximately 64 hours and 18 minutes to
  complete an orbit.

20
Vision, Hope, and Triumph Hubble Telescope

• http//www.nasa.gov/multimedia/nasatv/on_demand_vi
  deo.html?paramhttp//anon.nasa-global.edgesuite.n
  et/anon.nasa-global/ccvideos/GSFC_20081009_VisHope
  Tri.asx_id168629_titleVision2C20Hope2C20Tr
  iumph3A20The20Hubble20Space20Telescope_tnima
  ge281