TuesdaySeptember 25,
2012(Telescopes; HTUW: Alien
Galaxy Parts 2 & 3)
The Launch PadTuesday, 9/25/12
Please pick up your graded work off of the side table as you come in.
spirals
barred spirals
ellipticals
irregulars
30%
10%
60%
10%
large
very large
small or huge
varies
List the four types of galaxies, their relative abundance in the Universe,
and their relative sizes.
The Launch PadTuesday, 9/25/12
Identify
barred spiral galaxy
horsehead dark nebula
Announcements• None Today
Assignment Currently Open
Summative or
Formative?Date Issued Date Due Date Into
GradeSpeed Final Day
Quiz 3 S3 9/14 9/14 9/14 9/28
Lab – Distance and Spacing of
the PlanetsF6 9/17 9/18
Lab – Comparing the Terrestrial and Jovian Planets
F7 9/18 9/19
Quiz 4 S4 9/21 9/21 10/5
??
Recent Events in ScienceHubble Catches Glowing Gas and Dark Dust in a Side-On Spiral
The NASA/ESA Hubble Space Telescope has
produced a sharp image of NGC 4634, a spiral galaxy seen exactly side-on. Its
disk is slightly warped by ongoing interactions with a
nearby galaxy, and it is crisscrossed by clearly defined dust lanes and
bright nebulae.
http://www.sciencedaily.com/releases/2012/09/120924093957.htm
Read all about it!
VideoHow the Universe Works:
Alien Galaxy
Part 2 – Studying the Progress of Galaxies(6:06 – 10:43)
Optical (Visible Light) TelescopesAn optical telescope gathers
and focuses light mainly from the visible part of the electromagnetic
spectrum.
Optical telescopes increase the apparent angular size of distant objects
as well as their apparent brightness.
In order for the image to be observed, photographed, studied, and sent to a
computer, telescopes work by employing one or more curved optical
elements, usually made from glass lenses and/or mirrors, to gather and bring that light to a focal
point.
Optical (Visible Light) Telescopes
The two main types of optical telescopes are:
Refracting telescopes Reflecting telescopes
Refracting Optical TelescopesRefracting telescopes use a lens (called the objective) to
bend (refract) the light to produce an image.Light converges at an area called the focus.
The eyepiece is a second lens used to examine the image directly.
Refracting telescopes have an optical defect called chromatic aberration (color distortion.)
Reflecting Optical TelescopesReflecting telescopes use a concave mirror to gather
the light, and there is no color distortion.Nearly all large telescopes are of this type.
The Andromeda Galaxy using telescopes of different resolution.
The top picture is not “out of focus”, it’s a
resolving issue, not a focus problem.
Optical Resolution
Deployment of the Hubble Space Telescope in Earth Orbit
Figure 23.17
April 24, 1990
Radio Telescopes
Radio wavelength radiation reaches Earth’s surface, so
radio telescopes can be Earth-based.
Radio Telescopes
Radio telescopes are “big dishes” used to gather
radio wavelength electromagnetic
radiation.
Radio TelescopesRadio telescopes have to be very large in order to gather
radio waves, which are about 100,000 times longer than
visible radiation waves.They are often made of a
wire mesh, and have rather poor resolution.
Radio telescopes can be wired together into a
network called a “radio interferometer.”
A steerable radio telescope at Green Bank, West Virginia
Figure 23.15 A
Radio TelescopesRadio telescopes have several advantages over
optical telescopes: they are less affected by weather
they are less expensive to build and maintainthey can be used 24 hours a day
they are able to detect material that does not emit visible radiation
and, they can “see” through interstellar dust clouds
Radio Telescope Images
Microwave Telescopes
The Planck Microwave telescope
The Milky Way as the bright center area, with the
cosmic microwave background left over from the Big Bang shown as the orange mottling at the top and bottom edges of the
image.
Infrared TelescopesThese telescopes capture radiation in the infrared bands of the Electromagnetic Spectrum, therefore they are “seeing”
heat rather than visible light.
Spitzer Infrared Space Telescope
The Helix Nebula in infrared.
Ultraviolet Telescopes
The Hopkins Ultraviolet Telescopes
Our Sun in Ultraviolet
X Ray Telescopes
The Chandra X Ray Observatory
The supernova remnant Cassiopeia
A in X Ray
Gamma Ray Telescopes
The Fermi Gamma-ray Space Telescope
a gamma-ray image of the entire sky
taken over four days by Fermi
VideoHow the Universe Works:
Alien Galaxy
Part 3 – Black Hole in the Middle of the Milky Way Galaxy
(10:44 – 17:39)
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