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 Light gathering: telescopes collect more light than the human eye can capture on its own  Magnification.

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Presentation on theme: " Light gathering: telescopes collect more light than the human eye can capture on its own  Magnification."— Presentation transcript:


2  Light gathering: telescopes collect more light than the human eye can capture on its own  Magnification

3 cting.gif

4  Refraction - the bending of light due to the fact it slows down while going through a dense medium.

5  Size refers to the size of the objective lens  The bigger the objective lens, the more light gathering power the telescope has


7 Yerks Observatory, U Chicago Williams Bay, WI

8  Largest refractor  40 inch objective (102 cm)

9 The focal length of the objective lens Magnification = ------------------------------------------------ The focal length of the eyepiece How can you change the magnification without changing the light collecting power?

10  Which part of a refractor telescope is light gathering?  What does the magnification?

11  ESA: Eyes on the Skies Chapter 1  RxWg RxWg

12  After initial alignment, refractor optics are more resistant to misalignment  The glass surfaces are sealed inside the tube and rarely need cleaning.  The sealing also minimizes affects from air currents, providing steadier sharper images.

13  possible distortions of the lenses.  lenses need edge supported, this limits the size of any refractor  Lenses can “sag” over time  Chromatic aberration

14  only 1 frequency focuses at a time because of dispersion  each frequency slows a different amount in glass





19  100 inch mirror (2.5 m)  Biggest telescope between 1917 - 1948


21  California Institute of Technology  North of San Diego, CA  5 telescopes


23  Reflectors do not suffer from chromatic aberration (inability to focus all colors).

24  Mirrors are easier to build without defects than lenses, since only one side of a mirror is used.  because the support for a mirror is from the back, very large mirrors can be built, making larger scopes.

25  The disadvantages include easiness of misalignment and need for frequent cleaning.

26  For a telescope, why is bigger better?


28 TelescopeYears ImportantSize Yerks: U Chicago (Williams Bay, WI) Built 18971.02 m Hale: Mt. Wilson Institute, CA 19081.5 m Hooker: Mt. Wilson Institute, CA1917 2.5 m Hale: Palomar, Caltec CA 19485.1 m Keck I, Keck II: Mauna Kea, HI 199110 m

29  300 tons each http://amazing-

30 This is the rear of the primary mirror assembly



33  Using multiple small telescopes to form an image effectively simulating a much larger telescope 

34  "atmospheric distortion" is the reason that the stars seem to twinkle when you look up at the sky  atmosphere partially blocks or absorbs certain wavelengths of radiation, like ultraviolet, gamma- and X-rays, before they can reach Earth


36 Published 02 April 2009The University of Waikato

37  heat energy  Observed in dry, high altitude locations or space  Observation of:  galactic regions cloaked by dust  studies of molecular gases. NASA Infrared Telescope Facility- Mauna Kea, Hawaii


39  absorbed by atmospheric ozone  observed from very high altitude or space  best suited to the study of thermal radiation and spectral emission lines from hot blue stars that are very bright in this wave band View of the Astro-1 astronomical observation payload in the bay of Shuttle Columbia during the STS-35 mission of December 1990

40  absorbed by atmosphere  Observed by high altitude balloons, rockets, or from space Notable X-ray sources include:  X-ray binaries  pulsars  supernova remnants  active galactic nuclei Chandra X-ray Telescope

41 Fermi Bubbles - found by the Fermi telescope in 2010 - extend 20,000 light-years above and below our Milky Way galaxy.

42  objects-at-edge-of-electromagnetic- spectrum objects-at-edge-of-electromagnetic- spectrum Fermi Bubbles - found by the Fermi telescope in 2010 - extend 20,000 light-years above and below our Milky Way galaxy.

43  observed in space or indirectly with special ground based telescopes Steady gamma-ray emitters include:  Pulsars  neutron stars  black hole candidates such as active galactic nuclei Compton Gamma-ray Observatory launched on the Space Shuttle Atlantis, mission STS-37, on 5 April 1991 and operated until its de-orbit on 4 June 2000

44  Why do astronomers use a variety of telescopes?


46  Read Hubble Space Telescope-Eyes in the Sky  Complete the article/text analysis document


48 The new image (right) was taken with the second generation Wide Field and Planetary Camera (WFPC2), which was installed during the STS-61 Hubble Servicing Mission. The picture beautifully demonstrates that the corrective optics incorporated within WFPC2 compensate fully for Hubble's near- sightedness. The new camera will allow Hubble to probe the universe with unprecedented clarity and sensitivity. The picture clearly shows faint structure as small as 30 light-years across in a galaxy tens of millions of light-years away. An Early Release Observation Release / An American Astronomical Society Meeting Release January 13, 1994

49  353 miles (569 km) above the surface of Earth  Every 97 minutes, Hubble completes a spin around Earth  moving at the speed of about five miles per second (8 km per second) — fast enough to travel across the United States in about 10 minutes


51  Light hits the telescope's main mirror, or primary mirror  Light bounces off the primary mirror and encounters a secondary mirror  secondary mirror focuses the light through a hole in the center of the primary mirror that leads to the telescope's science instruments

52  The Wide Field Camera 3 (WFC3) sees three different kinds of light: near-ultraviolet, visible and near-infrared, though not simultaneously. Its resolution and field of view are much greater than that of Hubble's other instruments. WFC3 is one of Hubble's two newest instruments, and will be used to study dark energy and dark matter, the formation of individual stars and the discovery of extremely remote galaxies previously beyond Hubble's vision.Wide Field Camera 3

53  The Cosmic Origins Spectrograph (COS), Hubble's other new instrument, is a spectrograph that sees exclusively in ultraviolet light. Spectrographs acts something like prisms, separating light from the cosmos into its component colors. This provides a wavelength "fingerprint" of the object being observed, which tells us about its temperature, chemical composition, density, and motion. COS will improve Hubble's ultraviolet sensitivity at least 10 times, and up to 70 times when observing extremely faint objects.Cosmic Origins Spectrograph

54  The Advanced Camera for Surveys (ACS) sees visible light, and is designed to study some of the earliest activity in the universe. ACS helps map the distribution of dark matter, detects the most distant objects in the universe, searches for massive planets, and studies the evolution of clusters of galaxies. ACS partially stopped working in 2007 due to an electrical short, but was repaired during Servicing Mission 4 in May 2009.Advanced Camera for Surveys

55  The Space Telescope Imaging Spectrograph (STIS) is a spectrograph that sees ultraviolet, visible and near-infrared light, and is known for its ability to hunt black holes. While COS works best with small sources of light, such as stars or quasars, STIS can map out larger objects like galaxies. STIS stopped working due to a technical failure on August 3, 2004, but was also repaired during Servicing Mission 4.Space Telescope Imaging Spectrograph

56  The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is Hubble's heat sensor. Its sensitivity to infrared light — perceived by humans as heat — lets it observe objects hidden by interstellar dust, like stellar birth sites, and gaze into deepest space.Near Infrared Camera and Multi-Object Spectrometer

57  Finally, the Fine Guidance Sensors (FGS) are devices that lock onto "guide stars" and keep Hubble pointed in the right direction. They can be used to precisely measure the distance between stars, and their relative motions.Fine Guidance Sensors


59  The James Webb Space Telescope (sometimes called JWST) is a large, infrared-optimized space telescope. The project is working to a 2018 launch date. Webb will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. Webb's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.first galaxies that formed in the early UniverseGalaxydusty cloudsplanetary systems  Webb will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade won't fit onto a rocket fully open, so both will fold up and open once Webb is in outer space. Webb will reside in an orbit about 1.5 million km (1 million miles) from the Earth.mirror, 6.5 meters (21.3 feet) in diameter sunshield the size of a tennis courtrocketorbit about 1.5 million km  The James Webb Space Telescope was named after the NASA Administrator who crafted the Apollo program, and who was a staunch supporter of space science.NASA Administrator

60  What type of telescope would you want to use to observe the following:  Galactic nuclei such as black holes?  Interstellar gas and dust? Gamma Ray Telescope Radio or Infrared Telescopes

61  Pages/104/assignment.html Pages/104/assignment.html

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